ECE 467 Network Implementation Lab Manual

Transcription

ECE-467
Network Implementation
Laboratory and Experiment Guide
Second Edition
1
Spring 2006
Fall 2005
Lab
Date
Student Signature
1-A
1-B
2-A
2-B
3
4
Table 1 Lab completion verification
3
TA Signature
Table of Contents
PAGE
List of Figures ............................................................................................................................... 7
List of Tables .................................................................................................................................. 9
Abstract ......................................................................................................................................... 10
Introduction................................................................................................................................... 11
Premise for the Student Lab...................................................................................................... 11
World Wide Web Resources......................................................................................................... 14
CISCO Internetwork Operating System Commands .................................................................... 15
RACAL Configuration Instructions .......................................................................................... 17
Data Network Implementation Lab 1 ........................................................................................ 21
Reverse Telnet sessions over async ports ................................................................................. 21
Console and Auxiliary Port Signals and Pinouts ...................................................................... 23
Console Port Signals and Pinouts ......................................................................................... 24
Auxiliary Port Signals and Pinouts ....................................................................................... 24
Reverse Telnet Connections ..................................................................................................... 26
Data Network Implementation ................................................................................................... 30
Lab 1 part B ................................................................................................................................. 30
Local Area Network (LAN).................................................................................................. 30
Introduction............................................................................................................................... 30
Ethernet Standards background ............................................................................................ 31
Ethernet Cabling and Connectors ............................................................................................. 31
T w i s t e d Pair Cabling.......................................................................................................... 31
Unshielded Twisted Pair Cabling (UTP) .............................................................................. 32
Connecting to RJ-45 Network Interface Card on the PC...................................................... 33
IP Addressing configuration hints ................................................................................................ 35
ECE 467 .................................................................................................................................... 39
Lab 2-A ........................................................................................................................................ 39
Synchronous connection (PPP Cisco's HDLC) ........................................................................ 39
HDLC Overview................................................................................................................... 41
High-Level Data Link Control HDLC)................................................................................. 42
Data Network Implementation...................................................................................................... 43
Lab 2-B ......................................................................................................................................... 43
Routing Protocols...................................................................................................................... 43
RIP ........................................................................................................................................ 44
IGRP ..................................................................................................................................... 45
EIGRP / RIP with route redistribution.................................................................................. 45
Routing Protocol Overview .................................................................................................. 46
RIP characteristics ................................................................................................................ 47
IGRP' characteristics............................................................................................................. 47
EIGRP characteristics ........................................................................................................... 47
Routing Protocol Overviews..................................................................................................... 48
Routing Information Protocol (RIP) ......................................................................................... 48
Routing Updates........................................................................................................................ 48
4
RIP Routing Metric............................................................................................................... 48
RIP Stability Features ........................................................................................................... 49
RIP Timers ............................................................................................................................ 49
Packet Formats.......................................................................................................................... 49
RIP Packet Format ................................................................................................................ 49
RIP 2 Packet Format ................................................................................................................. 50
Internal Gateway Routing protocol (IGRP).......................................................................... 51
The Routing Problem.................................................................................................................... 52
Summary of IGRP..................................................................................................................... 53
Enhanced Internal Gateway Routing Protocol (EIGRP) ......................................................... 56
How Does EIGRP Work? ............................................................................................................... 56
EIGRP Concepts ........................................................................................................................... 57
Neighbor Table ......................................................................................................................... 57
Topology Table......................................................................................................................... 58
Feasible Successors................................................................................................................... 58
Route States .............................................................................................................................. 58
Packet Formats.......................................................................................................................... 59
Route Tagging........................................................................................................................... 59
Compatibility Mode .................................................................................................................. 60
Data Network Implementation .................................................................................................. 62
Lab 3............................................................................................................................................. 62
Frame Relay .............................................................................................................................. 62
Frame Relay Overview ............................................................................................................. 64
Using PVCs............................................................................................................................... 64
The Frame Relay Header and DLCI ......................................................................................... 65
Simple Rule: If there is a problem, discard the data ................................................................. 67
Summary ................................................................................................................................... 68
Lab 4............................................................................................................................................. 71
Asynchronous Transfer Method (ATM) ................................................................................... 71
ATM Network Design Overview.............................................................................................. 73
Designing ATM internetwork............................................................................................... 73
ATM Defined........................................................................................................................ 73
Role of ATM in Internetworks ............................................................................................. 74
Multiservice Networks.......................................................................................................... 74
TDM Network Migration...................................................................................................... 75
Reduced WAN Bandwidth Cost ........................................................................................... 75
Improved Performance.......................................................................................................... 75
Reduced Downtime............................................................................................................... 75
Integrated Solutions .............................................................................................................. 75
Different Types of ATM Switches ....................................................................................... 76
ATM Overview......................................................................................................................... 77
Structure of an ATM Network.............................................................................................. 77
General Operation on an ATM Network .............................................................................. 77
ATM Functional Layers........................................................................................................ 78
Physical Layer....................................................................................................................... 79
5
Physical Medium Sublayer ................................................................................................... 79
Transmission Convergence Sublayer.................................................................................... 79
ATM Layer ............................................................................................................................... 80
ATM Adaptation Layer (AAL)............................................................................................. 80
AAL1 .................................................................................................................................... 81
AAL3/4 ................................................................................................................................. 81
AAL5 .................................................................................................................................... 82
ATM Addressing .................................................................................................................. 82
Fields of an ATM Address.................................................................................................... 83
ATM Media .......................................................................................................................... 83
APPENDIX................................................................................................................................ 86
6
List of Figures
Figure 1 OSI layer communication............................................................................................... 12
Figure 2 RJ-48C cross-over .......................................................................................................... 21
Figure 3 RJ-45 straight through .................................................................................................... 21
Figure 4 RJ-45 Cross-over pinouts ............................................................................................... 22
Figure 5 AUI Transceiver connection........................................................................................... 22
Figure 6 GMU student lab asynchronous port connectivity ......................................................... 23
Figure 7 Connecting the console port to a PC .............................................................................. 24
Figure 8 Identifying a cross-over cable...................................................................................... 25
Figure 9 Lab 1-B Local Area Network Diagram .......................................................................... 30
Figure 10 Connection Guideline Example.................................................................................... 31
Figure 11 UTP Cable (4-pair) ....................................................................................................... 32
Figure 12 RJ-45 Connection Example.......................................................................................... 33
Figure 13 AUI Transceiver Connection Example ........................................................................ 34
Figure 14 Lab 2-A PPP Network diagram.................................................................................... 39
Figure 15 Point to Point Connection Example ............................................................................. 40
Figure 16 RJ-48C cross-over pinouts and signaling ..................................................................... 41
Figure 18 Lab 2-A PPP Network diagram.................................................................................... 43
Figure 19 Routing Information Protocol Lab ............................................................................... 44
Figure 20 IGRP Configuration...................................................................................................... 45
Figure 21 EIGRP / RIP and Route Redistribution lab .................................................................. 46
Figure 22 IP RIP packet consists of nine fields. ........................................................................... 49
Figure 23 IP RIP 2 packet consists of fields similar to those of an IP RIP packet. ...................... 50
Figure 24 Lab 3 Frame Relay Network diagram...................................................................... 62
Figure 25 DTE to DCE Physical Connection example................................................................. 63
Figure 26 Frame Relay Data Link and Network Layer Connectivity ..................................... 63
Figure 27 Basic Frame Structure .................................................................................................. 65
Figure 28 Frame Relay Frame Header.......................................................................................... 66
Figure 29 Frame Relay Example .................................................................................................. 67
Figure 30 Lab 4 Asynchronous Transfer Method......................................................................... 71
Figure 31 ATM Connectivity Example ........................................................................................ 72
Figure 32 ATM Support of various traffic types .......................................................................... 74
Figure 33 The Role of ATM Switches in a Network.................................................................... 76
Figure 34 Components of an ATM Network................................................................................ 77
Figure 35 Establishing a connection in an ATM network. ........................................................... 78
Figure 36 Relationship of ATM functional layers to the OSI reference model............................ 79
Figure 37 AAL3/4 cell preparation............................................................................................... 81
Figure 38 AAL5 cell preparation.................................................................................................. 82
Figure 39 ATM address formats ................................................................................................... 83
Figure 40 Lab 1A initial diagram................................................................................................. 87
Figure 41 Lab 1A configuration example..................................................................................... 88
Figure 42 Lab 1A pinouts ............................................................................................................. 89
Figure 43 Lab 1b Ethernet configuration...................................................................................... 90
Figure 44 Lab 1b configuration example..................................................................................... 91
Figure 45 Lab 1b ethernet straight through cable ......................................................................... 92
7
Figure 46 Lab 1b ethernet crossover cable ................................................................................... 93
Figure 47 Lab 2a PPP network ..................................................................................................... 94
Figure 48 Lab 2a WAN connectivity........................................................................................... 95
Figure 49 Lab 2a Cross connect cable .......................................................................................... 96
Figure 50 Lab 2b Routing diagram............................................................................................... 97
Figure 51 Lab 2b Route redistribution example .......................................................................... 98
Figure 52 Lab 2b IGRP routing example...................................................................................... 99
Figure 53 Lab 2b IGRP configuration ....................................................................................... 100
Figure 54 Lab 2b RIP diagram.................................................................................................... 101
Figure 55 Lab 2b RIP configuration .......................................................................................... 102
Figure 56 Lab 3 Frame relay diagram......................................................................................... 103
Figure 57 Lab 3 Frame relay setup ............................................................................................. 104
Figure 58 Lab 3 connectivity ..................................................................................................... 105
Figure 59 Lab 4 ATM diagram.................................................................................................. 106
Figure 60 Lab 4 connectivity ..................................................................................................... 107
Figure 61 Lab 4 ATM pinouts .................................................................................................... 108
Figure 62 RACAL crossover cable............................................................................................ 109
Figure 63 RJ48C crossover cable ............................................................................................... 110
Figure 64 Cisco cable.................................................................................................................. 111
Figure 65 Ethernet cable ............................................................................................................. 112
Figure 66 Ethernet crossover cable............................................................................................. 113
Figure 67 Cisco adapter .............................................................................................................. 114
8
List of Tables
Table 1 Lab completion verification............................................................................................... 3
Table 2 Async port to DB-25 Pinout ............................................................................................ 24
Table 3 Auxiliary port pinout and signaling ................................................................................. 25
Table 4 Ethernet Cabling Pinout and Signaling............................................................................ 34
Table 5 AUI Pinout and signaling ................................................................................................ 35
Table 6 Summary of Subnetting Parameters ................................................................................ 36
Table 7 Sample Routing Table ..................................................................................................... 53
Table 8 ATM Adapter Layers....................................................................................................... 80
Table 9 ATM Physical rates ......................................................................................................... 84
9
ECE 467
Local Area / Wide Area Network
Implementation Laboratory
Revised by Aleksander Lazarevich
Abstract
In order to help students further develop computer and data communication skills, it is
necessary for the student to get some hands on experience. Hands on experience will compliment the knowledge the students are getting in the classroom. The best way for the students
to obtain this experience would be in a real world environment. In the absence of this scenario the best way for the students to obtain this experience would be in a lab that simulates
the real world environment.
To further develop the students' skills a set of lab sessions were prepared by Mr. José
Rivera. The students were taken from the classroom environment to a simulated live environment (the laboratory). In this environment the students were exposed to real world scenarios
such as Local Area Network implementation, asynchronous communication setup, reverse telnet
session setup, Wide Area Network implementation using various protocols (HDLC (point -topoint session), Frame Relay, and ATM), and routing protocols (static routes, RIP, IGRP, and
EIGRP).
This text will focus on the student laboratory concept, detail description of the labs,
and the student experience in the lab. This text is an updated version of Mr. Rivera’s original
project to a more formal format.
10
ECE 467
Local Area / Wide Area Network
Implementation Laboratory
Introduction
In order to help students further develop computer and data communication skills,
it is necessary for the student to get some hands on experience. Hands on experience will
compliment the knowledge the students are getting in the classroom. The best way for the
students to obtain this experience would be in a real world environment. In the absence of
this scenario the best way for the students to obtain this experience would be in a lab that
simulates the real world the environment.
Working in a lab environment will allow the students to learn about the real world environment, it will provide them with hands on experience, and most of all it will allow
them to make mistakes without repercussions. The purpose of this environment is:
1) To introduce the students to communication equipment.
2) To introduce the students to real life scenarios.
3) To teach students to configure and maintain communications equipment.
4) To help the students develop techniques to approach problem solving.
5) To show the students the many applications of theory they have been learning in
school.
Premise for the Student Lab
The student lab will be a data and computer communication lab. In most communications
environment, there is a separation between the communication functions and applications processing. This lab will be based on the Open Systems Interconnect model (OSI), which has the following seven layers:
Layer
Description
7
Application
6
Presentation
5
Session
4
Transport
3
Network
2
Data Link
1
Physical
Although most protocol suites do not match the OSI model exactly, mappings can be made to
the OSI model. In order for "peer-to-peer communications" to take place each layer uses it's
own layer protocol to communicate with it's peer layer in the other system (please refer to diagram).
11
Application
Presentation
Presentation
Session
Session
segments
segments
Transport
Network
Data Link
Physical
packets
frames
bits
Network
Network
Data Link
Data Link
Physical
Physical
packets
frames
bits
Transport
Network
Data Link
Physical
Figure 1 OSI layer communication
Each layer's protocol exchanges information, called protocol data units (PDUs), between peer layers. A given layer can use a more specific name for its PDU.
In the lab we will focus on the lower three layers (physical, data link and network
layers). Although all seven layers will be used to verify network functionality the lab
exercises will focus to the lower three layers.
It is assumed that the student has already been exposed to the OSI seven layer model
and how each of the layers works with its peer layer; the lab exercises will focus on
their implementation rather than their explanation.
The following labs will be developed:
1)
Lab 1: Asynchronous Port and Local Area Network configurations. In this
lab the student will be exposed to local area networks and their configuration.
Students will learn about Ethernet configuration, network interface cards,
Ethernet cables (straight through and cross over), hubs and PC configuration.
The student will also use the TCP/IP protocol to provide network connections.
In the second part of the lab they will learn how to configure asynchronous
ports on routers in order to access any serial device such as console port, serial
printers, x.25 pads, modems, etc. They will also learn how to setup a reverse
telnet session in order to access devices remotely.
2) Lab 1-B: Wide Area Network (PPP WAN connectivity). In this lab the students
will build on the skills learned in lab 1. They will build a network using point-topoint protocol. The students will be introduced to physical layer configuration
(configuration of CSU/DSU); they will configure the data link and network layer
in order to provide network connectivity. In order to route the network they will
use static tables
12
.
3)
Lab 2: Routing Protocols.
In this lab the students will use the network built in lab 1. Instead of using static routing tables,
the following scenarios will be built: a) a RIP routed network, b) An IGRP routed network, and
c) an IGRP / EIGRP routed network. In this lab the students will be exposed to various routing
protocols, and different scenarios will be simulated (network outages), so the students can see
first hand routing loop problems, counting to infinity and possible solutions (split horizon, hold
down timer, and route poisoning).
4)
Lab 3: Frame Relay WAN Network
In this lab the students will use the network built in lab 1 and will build a Frame Relay network. The students will learn the difference between DTE and DCE devices; they will team to
provide clocking. The students will learn to configure the data link layer for the edge devices
and the data link layer for the frame relay-switching device.
5)
Lab 4: ATM WAN Network
In this lab the students will be exposed to ATM. However it should be noted that the ATM links
will configured as IP over ATM, and not as an ATM Switch. The students will be exposed to
DS3 and OC3 interfaces and their physical and data link configurations. The students will
learn how to build ATM VCs and how to route them.
13
World Wide Web Resources
http://www.techfest.com/
(Good Technical reference site)
http://www.techguide.com
(Good Technical reference site)
http://www.cisco.com
(Cisco's Web site)
http://www.atmforum.com
(ATM Forum's Web site)
http://www.frforum.com
(Frame Relay forum's Web site)
http://www.itu.org
(International Telecommunications Union web site, great site but it is a user PAID
site)
14
CISCO Internetwork Operating System Commands
In order to configure a router, the student must transition the router from user mode to the
privilege mode (also known as the enable mode). The convention in this section is that the scree
prompts will be in italics and what the student is to type will be in bold. At the router prompt
(RouterName>) type enable and press enter. The student will receive a prompt for the Password
(Password: ) at which time the student is to enter the appropriate password. The return prompt will
show that the student is in the privilege mode (RouterName#). This level may be exited by typing
disable. At any point in the configuration, the student may find out what commands are available
by typing “show ?”. The system will list the available commands. If the student wishes to find
commands beginning with a letter sequence, they may type “if?” for those commands that begin
with if. If the student wants to find those reserved words that may be combined with another reserved word, they would type the word of interest and a “?” with a space between the word and the
question mark.
At this point the student should enter the configuration mode by typing configure terminal. The return prompt will be RouterName(config)#. Each of these levels may be exited by typing
exit or Ctrl-Z. From the config level, you may enter information directly into the router global
configuration or enter into on of the other three configuration levels. Each of these subsequent levels may be entered from this level. To transition from one of the subsequent levels to another, the
student must exit one and then enter the other.
The interface configuration mode is enter by using the reserved word interface followed by
the interface the student wishes to configure, such as ethernet0, serial0, or serial1. This mode is
exited by using exit or Ctrl-Z. The identifying prompt is RouterName(config-if)#. The shutdown
command will disable an interface and the no shutdown command will enable an interface that
has been disabled. An interface may be configured to act as multiple interfaces by describing each
as a subinterface. For example, s0 may be configured as s0.1, s0.2, etc.
The line configuration mode is entered by using the reserved word line followed by the line
to be configured, such as vty, console, tty, or async along with the appropriate line number. This
mode is exited by using exit or Ctrl-Z. The identifying prompt is RouterName(config-line)#.
The routing protocol configuration mode is entered by typing the reserved word router followed by the routing protocol to be configured such as rip, igrp, eigrp, or ospf. This mode is exited
by using exit or Ctrl-Z. The identifying prompt is RouterName(config-router)#.
To view the current configuration type RouterName#show running-config.
To view the current interface configurations type show int e0 for interface Ethernet0, show
int s0 for interface serial0, etc. The command show version will display all of the router’s information concerning what IOS is installed and what the hardware configuration contains. The command show users details who is logged into the router. The command show cdp neighbor details
the routers directly connected to your router.
Serial interfaces may be encapsulated. The reserved encapsulations are ppp, hdlc, and
15
Frame Relay. In ppp, echo requests (or pings) are used to keep the interface alive. To disable
this feature, no keepalives is used. The hdlc encapsulation may only be used if there is a Cisco
router at each end of the link. This option is rarely used. The Frame Relay encapsulation is used
in order to manage the required virtual circuit (VC) configuration in frame relay as well as the
Data Link Connection Identifier (DLCI). The command sequence would look like:
• encapsulation frame-relay ietf
• frame-relay interface-dlci 100 (where 100 is the circuit ID number)
• frame-relay map ip 192.168.0.1 100 (this maps the ip address assigned to the specific
interface to the desired dlci.)
For ATM, the interface configuration is identified as atm0.
After the configuration is complete, the student needs to execute either a write memory command
or a copy running config startup-config to insure that when the router is rebooted, the configuration is not lost.
If the running configuration needs to be cleared, the command sequence is:
RouterName#erase nvram or erase startup-config <enter>
Erasing the nvram filesystem will remove all files! Continue? [confirm]<enter>
[OK]
RouterName#reload<enter>
Proceed with reload? [confirm] <enter>
Password
16
RACAL Configuration Instructions
17
18
19
20
ECE 467
Data Network Implementation Lab 1
Reverse Telnet sessions over async ports
In the first lab the student will get familiar with serial port communications. The students
will need to get familiar with RS-232 communications and how async ports can be setup as terminal server ports. In this lab the async ports will be used to perform reverse telnet sessions to
remote devices. The initial task is for the student to build several cables that will be needed
throughout this lab as well as those to follow. These cables are an RJ-45 straight through, an RJ45 cross-over and an RJ-48 cross-over. These cables need to be brought to the lab each week and
labeled with the student name and type. The wire breakouts are shown below.
Figure 2 RJ-48C cross-over
Figure 3 RJ-45 straight through
21
Figure 4 RJ-45 Cross-over pinouts
An AUI transceiver is connected to a router in the following manner:
Figure 5 AUI Transceiver connection
The following depicts the connections that will be required for this lab.
22
Figure 6 GMU student lab asynchronous port connectivity
In the real world this functionality is useful when remotely managing devices from a
centralized location. In the lab environment this function will be useful in the aid of
router configuration during subsequent labs and to help students troubleshoot problems
they may encounter during the labs.
This lab will require the following equipment:
A) Cisco Router 2509 (this router has 16 async ports, 2 serial ports, and 1
Ethernet port)
B) (7) rj-45 flat satin cables, suing all 8 conductors.
C) (8) rj-45 to DB-25 RS-232 cable converter.
D) Devices to provide reverse telnet sessions.
Console and Auxiliary Port Signals and Pinouts
(Console port / Async port information came from Cisco's web site at ww.cisco.com)
Routers come with a console and auxiliary cable kit, which contains the cable and
adapters you need to connect a console terminal (an ASCII terminal or PC running
terminal emulation software) or modem to your router. The console and auxiliary cable kit includes the following items:
•
•
•
•
RJ-45-to-RJ-45 rollover cable
RJ-45-to-DB-9 female DTE adapter (labeled TERMINAL)
RJ-45-to-DB-25 female DTE adapter (labeled TERMINAL)
RJ-45-to-DB-25 male DCE adapter (labeled MODEM)
23
Console Port Signals and Pinouts
Use the thin, flat, RJ-45-to-RJ-45 roll-over cable and RJ-45-to-DB-9 female
DTE adapter to connect the console port to a PC running terminal emulation software. The diagram in figure 3 shows how to connect the console port to a PC.
Figure 7 Connecting the console port to a PC
Table 2 lists the pinouts for the asynchronous serial console port, the RJ-45-to-RJ-45 rollover
cable, and the RJ-45-to-DB-25 female DTE adapter. This will also be the connection type you
will need to connect your Router Async port to other routers console port. Pinouts were obtained from Cisco's documentation.
Console port signaling and
cabling using a DB-25
adapter console port (DTE) 1
Signal
RTS
DTR
TxD
RJ-45 to RJ-45 crossover cable
RJ-45 to DB-25 terminal adapter
RJ-45 pin
12
2
3
RJ-45 pin
8
7
6
DB-25 pin
5
6
3
GND
GND
RxD
DSR
CTS
4
5
6
7
81
5
4
3
2
1
7
7
2
20
4
Console
device
Signal
CTSS
DSR
RxD
p
GND
GND
TxD
DTR
RTS
Table 2 Async port to DB-25 Pinout
Auxiliary Port Signals and Pinouts
Table 2 lists the pinouts for the asynchronous serial auxiliary port, the RJ-45-to-RJ-45 rollover
1
2
You can use the same cabling to connect a console to the auxiliary port.
Pin 1 is internally connected to pin 8
24
cable, and the RJ-45-to-DB-25 male DCE adapter. Pinout obtained from Cisco’s documentation.
Auxiliary port signaling
and cabling using a DB-25
adapter auxiliary port
(DTE)
Signal
RJ-45 to RJ-45 crossover cable
RJ-45 pin
RTS
DTR
TxD
GND
GND
RxD
DSR
CTS
13
2
3
4
5
6
7
83
RJ-45
pin
8
7
6
5
4
3
2
1
RJ-45 to DB-25
modem adapter
modem
DB-25 pin
Signal
5
6
3
7
7
2
20
4
CTSS
DSR
RxD
GND
GND
TxD
DTR
RTS
Table 3 Auxiliary port pinout and signaling
You can identify a cross-over cable by comparing the modular plugs at the two ends of the cable.
When you hold the plugs side by side, with the tab at the back, the wire connected to the pin on the
outside of the left plug should be the same color as the wire connected to the pin on the outside of
the right plug. (See Figure 4) If you purchased your cable from Cisco Systems, pin 1 is white on
one connector, and pin 8 is white on the other (a rollover cable connects pins 1 and 8, 2 and 7, 3 and
6, and 4 and 5).
Figure 8 Identifying a cross-over cable
3
Pin 1 is internally connected to pin 8
25
Reverse Telnet Connections
(For detailed information, go to Cisco web site at:
verse Telnet sessions).
www.cisco.com
and search on Async ports or Re-
It is important to note that the communication server (Cisco 2509) in addition to initiating connections can receive incoming connections on asynchronous lines. This capability allows you to attach serial printers, modems, and other shared peripherals to the communication
server and drive them remotely from other systems. The communication server supports reverse
Telnet connections.
The specific TCP port or socket to which you attach the peripheral device determines the
type of service the communication server provides on that line. When you attach the serial
lines of a computer system or a data terminal switch to a line of the communication server, the
communication server will act as a network front end for a host that does not support the
TCP/IP protocols. This arrangement is sometimes called front-ending or reverse connection
mode.
To connect an asynchronous line on a communication server, the remote host or terminal must specify a particular TCP port on the communication server. If Telnet protocols are
required, that port is 2000 (decimal) plus the decimal value of the line number. If a raw TCP
stream is required, the port is 4000 (decimal) plus the decimal line number. The raw TCP
stream is usually the required mode for sending data to a printer. The Telnet protocol requires
that carriage return characters be translated into carriage return and linefeed character pairs. You
can turn this translation off by specifying the Telnet binary mode option. To specify this option,
you must connect to port 6000 (decimal) plus the decimal line number.
26
27
28
29
ECE 467
Data Network Implementation
Lab 1 part B
Local Area Network (LAN)
Introduction
Ethernet is the most widely used local area network (LAN) technology. The original and
most popular version of Ethernet supports a data transmission rate of 10 Mb/s. Newer versions of
Ethernet called "Fast Ethernet" and "Gigabit Ethernet" support data rates of 100 Mb/s and 1 Gb/s
(1000 Mb/s). An Ethernet LAN may use coaxial cable, special grades of twisted pair wiring, or fiber
optic cable. "Bus" and "Star" wiring configurations are supported. Ethernet devices compete for access to the network using a protocol called Carrier Sense Multiple Access with Collision Detection
(CSMA/CD).
For this lab we will build a LAN based on Ethernet with data transmissions rate of 10
Mb/s. Figure 1 depicts the network that will be built during this lab.
E1
192.168.200.1
mask 255.255.255.0
E0
Seatle192.168.100.1
mask 255.255.255.0
192.168.100.2
mask 255.255.255.0
`
E1
192.168.200.3
mask 255.255.255.0
E0
192.168.300.3
E0
mask 255.255.255.0
192.168.300.1
Chicago
Washington
mask 255.255.255.0
E0
Dallas 192.168.100.3
mask 255.255.255.0
192.168.300.4
mask 255.255.255.0
192.168.300.2
mask 255.255.255.0
192.168.100.4
mask 255.255.255.0
`
`
Figure 9 Lab 1-B Local Area Network Diagram
The following equipment will be required for this lab:
A) (4) Routers with an Ethernet interface
B) (4) Personal computers with serial and Ethernet ports, to provide Async and
Ethernet connectivity.
C) AUI transceivers (for router Ethernet interfaces as needed).
D) (3) Ethernet hubs.
30
`
E) (10) Ethernet cables (straight through).
The following diagram gives a sample on how connections should be made between
routers/hubs/pc's.
Figure 10 Connection Guideline Example
Ethernet Standards background
Ethernet Cabling and Connectors
The information for Ethernet LAN was obtained from "techfest", you can find this and more information at their website at: http://www.techfest.cominetworkina/lan/ethernet.htm
Tw isted Pair Cabling
Twisted pair cables are so named because pairs of wires are twisted around one another. Each pair
consists of two insulated copper wires twisted together. The wire pairs are twisted because it helps
reduce crosstalk and noise susceptibility. High quality twisted pair cables have 1 to 3 twists per inch.
For best results, the twist rate should vary significantly between pairs in a cable.
Twisted pair cables are used with the following Ethernet physical layers: 10Base-T, 100Base-TX,
100Base-T2, IOOBase-T4, and 1000Base-T. The following sections describe the various types of
twisted pair cabling.
31
Figure 11 UTP Cable (4-pair)
Unshielded Twisted Pair Cabling (UTP)
As the name implies, "unshielded twisted pair" (UTP) cabling is twisted pair cabling
that contains no shielding. For networking applications, the term UTP generally refers to the 100
ohm, Category 3, 4, & 5 cables specified in the TIA/EIA 568-A standard. Category 5e, 6, & 7
standards have also been proposed to support higher speed transmission. UTP cabling most
commonly includes 4 pairs of wires enclosed in a common sheath. 10Base-T, 100Base-TX, and
100Base-T2 use only 2 of the twisted pairs, while 100Base-T4 and 1000Base-T require all 4
twisted pairs. The following is a summary of the UTP cable Categories:
•
Category 1 & Category 2 - Not suitable for use with Ethernet.
•
Category 3 - Unshielded twisted pair with 100 ohm impedance and electrical characteristics supporting transmission at frequencies up to 16 MHz. Defined by the TIA/EIA 568-A
specification. May be used with 10Base-T, 100Base-T4, and 100Base-T2.
•
specification. May be used with 10Base-T, 100Base-T4, and 100Base-T2.
•
specification. May be used with 10Base-T, 100Base-T4, 100Base-T2, and 100Base-TX.
May support 1000Base-T, but cable should be tested to make sure it meets 100Base-T
specifications.
•
Category 5e - Category 5e (or "Enhanced Cat 5") is a new standard that will specify
transmission performance that exceeds Cat 5. Like Cat 5, it consists of unshielded
twisted pair with 100 ohm impedance and electrical characteristics supporting transmission at frequencies up to 100 MHz. However, it has improved specifications for NEXT
(Near End Cross Talk), PSELFEXT (Power Sum Equal Level Far End Cross Talk), and
Attenuation. To be defined in an update to the TIA/EIA 568-A standard. Targeted for
1000Base-T, but also supports 10Base-T, 100Base-T4, 100Base-T2, and 100BaseTX.
•
Category 6 - Category 6 is a proposed standard that aims to support transmission at frequencies up to 250 MHz over 100 ohm twisted pair.
32
•
Category 7 - Category 7 is a proposed standard that aims to support transmission at frequencies up to 600 MHz over 100 ohm twisted pair.
Connecting to RJ-45 Network Interface Card on the PC
An "RJ-45" connector is used on Ethernet twisted pair links. This includes the l0Base-T, 100BaseTX, 100Base-T4, 100Base-T2, and 1000Base-T physical layer types. An RJ-45 connector has 8-pins,
and may also be referred to as an "8-pin Modular Connector". A male RJ-45 "plug" is mounted on
each end of the twisted pair cable. A female RJ-45 "jack" or "receptacle" is integrated into the
Ethernet hub or NIC.
Figure 12 RJ-45 Connection Example
The following table shows the RJ-45 connector pin assignments for each of the Ethernet
twisted pair physical layer types.
33
Contact
4
10Base-T
Signal
TD+
(Transmit
Data)
TD- (Transmit
Data)
RD+ (Receive
Data)
Not used
100Base-TX
Signal
TD+
(Transmit
Data)
TD- (Transmit
Data)
RD+ (Receive
Data)
Not used
5
Not used
Not used
6
7
RD- (Receive
Data)
Not Used
RD- (Receive
Data)
Not Used
8
Not Used
Not Used
1
2
3
100Base-T4
Signal
TX_D I+
(Transmit Data)
100Base-T2
Signal
BI_DA+ (Bidi
Data)
1000Base-T
Signal
BI_DA+ (Bidi
Data)
TX_D1(Transmit Data)
RX_D2+
(Receive Data)
BI_D3+ (Bidi
Data)
BI_D3 (Bidi
Data)
RX_D2(Receive Data)
BI_D4+ (Bidi
Data)
BI_D4 (Bidi
Data)
BI_DA- (Bidi
Data)
BI_DB+ (Bidi
Data)
Not used
BI_DA- (Bidi
Data)
BI_DB+ (Bidi
Data)
BI_DC+ (Bidi
Data)
BI_DC- (Bidi
Data)
BI_DB- (Bidi
Data)
BI_DD+ (Bidi
Data)
BI_DD (Bidi
Data)
Not used
BI_DB- (Bidi
Data)
Not used
Not used
Table 4 Ethernet Cabling Pinout and Signaling
AUI Transceiver used to connect to Routers.
Figure 13 AUI Transceiver Connection Example
The following table shows the assignment of the 15-pin AUI, or "attachment unit interface",
connector:
34
Table 5 AUI Pinout and signaling
IP Addressing configuration hints
It is assumed that the students have been exposed to the TCP/IP protocol and addressing schemes. If
the student needs to learn or brush up their IP skills, I recommend going to the following web site:
http://www.techfest.com/networking/prot.htm
When using IP routing on an interface, provide the IP address and subnet mask bits for that interface. Indicate values on the worksheet as follows:
•
IP address - Internet addresses are 32-bit values assigned to hosts that use the IP protocols.
These addresses are usually written in dotted decimal format (four decimal numbers separated by periods) such as 192.17.5.100. Each number is an 8-bit value between 0 and 255.
The addresses are divided into three classes; the classes differ in the number of bits allocated
to the network and host portions of the address.
The Class A Internet address format allocates the highest 8 bits to the network field
and sets the highest-order bit to 0 (zero). The remaining 24 bits form the host field.
The Class B Internet address allocates the highest 16 bits to the network field and
sets the two highest-order bits to I, 0. The remaining 16 bits form the host field.
The Class C Internet address allocates the highest 24 bits to the network field and
sets the three highest-order bits to I, I, 0. The remaining 8 bits form the host field.
Default: None.
Action: Enter your Internet address in dotted decimal form (for example,
35
131.108.2.5) for each installed serial interface you plan to configure.
The table below provides a summary of subnetting parameters.
First Class First Byte Network Bits Host Bits
A
I-126
8
24
B
128-191 16
16
C
192-223 24
8
Table 6 Summary of Subnetting Parameters
•
Subnet mask bits - Subnetting is an extension of the Internet addressing scheme, which allows multiple physical networks to exist within a single Class A, B, or C network. The usual
practice is to use a few of the far left bits in the host portion of the network address for a
subnet field. The subnet mask controls whether subnetting is in effect on a network. Internet addressing conventions allow 24 bits for a Class A address, 16 bits for a Class B address,
or 8 bits for a Class C address. However, because the last two of these bits are used for the
host address, the setup command facility allows you to specify up to 22, 14, or 6 bits for
your subnet mask.
Default: 0.
Action: Subnet mask bits should be defined as a decimal number between 0 and 22 for
Class A addresses, 0 and 14 for Class B addresses, or 0 and 6 for Class C addresses. Do
not specify 1 as the number of bits for the subnet field. That specification is reserved by
Internet conventions.
36
37
38
ECE 467
Lab 2-A
Synchronous connection (PPP Cisco's HDLC)
In Lab 2 the student will become familiar with Routing protocols and how to distribute and assign weights to routes. In order to do this the students will have to build several Local Area Networks (using the knowledge build on Lab I), and they will have to connect these Networks via
serial interfaces. The diagram in figure 14 depicts the network the students will build. These connections will be Point-to-Point using Serial ports. To simulate the Wide Area Network, a pair of
CSU/DSU (Channel service Unit / Data Service Unit) units will be used per connection. The diagram in figure 15 depicts how these connections should be terminated.
Figure 14 Lab 2-A PPP Network diagram
39
Figure 15 Point to Point Connection Example
It is important to note the following when configuring the devices for this lab:
HDLC encapsulation is the default encapsulation protocol for Cisco Routers, hence no configuration are needed to enable this protocol. This will not be the case for Lab 3 in which Frame Relay
will be the encapsulation protocol.
A. We will be using IP as our Network layer protocol. Each Serial Interface will need an IF'
address. In order to maximize address space a subnet mask of 255.255.255.252 will be
used on all the serial interfaces. Careful address planning should be taken in order to
avoid network errors.
B. The router's serial ports will be Data Terminal Equipment ports (DTE). No additional
configurations are needed on the routers for this function; a V.35 DTE cable will be
needed to connect the router's serial port to the DTE port in the CSU/DSU. If the port
needed to be a Data Computer Equipment (DCE) port, Bandwidth and Clock rates would
be required. This will be the case in lab 3 or the Frame Relay Lab.
C. For this Lab the Physical Layer (transmission equipment) needs to be properly configured. The CSU/DSU will represent this layer in this Lab. Since the Wide Area Network
will be represented by the CSU/DSU it is important to perform the following configuration on the CSU/DSU:
The Network Cloud will be represented by a T-I Cable (RJ-48C, see pinouts in figure 3). Hence
one of the CSU/DSUs has to be configured to provide the clock and the other to receive the clock
over the line. The Physical cable is referred to as DS1.
•
The DTE / DSO Channels need to be configured. A DS 1 has 24 DS0 Channels.
The Channels can be configured as either 56K or 64K; on a DS1 line you cannot
mix 56k and 64k channels. For this lab the channels will be configured as 64K.
Next the number of channels will need to set in the lab we will use all 24 DS0
channels (24 x 64K = 1.536 Mbps). Next you will configure the Transmit clock
40
to "Slave" (This clock faces the Router port and not the network).
•
The channels that were assigned in the previous step (24 in our case) need to be
mapped to DS 1 link.
•
It is important to note that both CSU/DSUs need to be configured. They will both
be configured the same, with the exception of the DSI Transmit Clock, in which
one side has to be configured to provide clock and the other side to receive clock.
E) It is important to note that during this section of the lab the routing protocols have not been
configured. That implies that the LAN will not be able to communicate with each other at this
point. However each router will be able to ping its peer router.
The diagram in figure 16 shows the pinout for a T-l RJ-48C connection.
Figure 16 RJ-48C cross-over pinouts and signaling
HDLC Overview
The following information was downloaded from the Cisco website and can be found at www.cisco.com.
Despite the fact that it omits several features used in SDLC, HDLC is generally considered to be a compatible superset of SDLC. LAP is a subset of HDLC and was created to ensure
ongoing compatibility with HDLC, which had been modified in the early 1980s. IEEE 802.2 is a
modification of HDLC for LAN environments. Qualified Logical Link Control (QLLC) is a linklayer protocol defined by IBM that enables SNA data to be transported across X.25 networks.
41
High-Level Data Link Control HDLC)
HDLC shares the frame format of SDLC, and HDLC fields provide the same functionality as
those in SDLC. Also, as in SDLC, HDLC supports synchronous, full-duplex operation. HDLC
differs from SDLC in several minor ways, however. First, HDLC has an option for a 32-bit
checksum. Also unlike SDLC, HDLC does not support the loop or hub go-ahead configurations.
The major difference between HDLC and SDLC
is that SDLC supports only one transfer
mode, whereas HDLC supports three:
•
Normal response mode (NRM) - This transfer mode is also used by SDLC. In this mode,
secondaries cannot communicate with a primary until the primary has given permission.
•
Asynchronous response mode (ARM) - This transfer mode enables secondaries to initiate
communication with a primary without receiving permission.
•
Asynchronous balanced mode (ABM) - ABM introduces the combined node, which can
act as a primary or a secondary, depending on the situation. All ABM communication occurs between multiple combined nodes. In ABM environments, any combined station can
initiate data transmission without permission from any other station.
Configuration example
(Serial Port configuration only)
42
ECE 467
Lab 2-B
Routing Protocols
In Lab 2 Section B the students will get familiarized with Routing protocols and how to distribute and assign weights to routes. They will use the network built in Lab 2 Section A, the diagram
in figure 1 depicts this network.
Figure 17 Lab 2-A PPP Network diagram
43
RIP
This section of the lab will consist of three parts. In the first part the students will use RIP (Routing Information Protocol). The diagram in figure 18 depicts this network.
Figure 18 Routing Information Protocol Lab
During this lab the students will enable RIP on all the routers and thus allow all the networks to
communicate with each other. The students will learn how to enable this protocol, and how to
assign weights to the various metrics (please see the section on RIP later in this document for
more information about this protocol). Once the Routing protocol is enabled, all the LAN will be
able to communicate with each other, and data transfer can be demonstrated.
44
IGRP
In the second part of this lab the students will use IGRP (Interior Gateway Routing Protocol).
The diagram in figure 19 depicts this network.
Figure 19 IGRP Configuration
During this lab the students will enable IGRP on all the routers and thus allow all the networks to
communicate with each other. The students will learn how to enable this protocol, and how to
assign weights to the various metrics (please see the section on IGRP later in this document for
more information on this protocol). Once the Routing protocol is enabled, all the LANs will be
able to communicate with each other, and data transfer can be demonstrated. It is important to
note that IGRP is a Cisco proprietary routing protocol.
EIGRP / RIP with route redistribution
In the third part of this lab the students will use EIGRP (Enhanced Interior Gateway Routing
Protocol), RIP (Routing Information Protocol), and route redistribution command. The diagram
in figure 4 depicts this network.
45
Figure 20 EIGRP / RIP and Route Redistribution lab
During this lab the students will enable EIGRP and RIP (as shown on the router) which will allow all the networks to communicate with each other. The students will learn how to enable
these protocols, how to redistribute tables and how to assign weights to the various metrics
(please see the section on EIGRP / RIP later in this document for more information on these protocols). Once these Routing protocols are enabled, all the LAN will be able to communicate with
each other, and data transfer can be demonstrated. It is important to note that EIGRP is a Cisco
proprietary routing protocol that has been submitted for standard approval. It is important to note
EIGRP has the same functionality as the IGRP protocol, however EIGRP supports all the protocol (IPX, IP, and Apple Talk) where IGRP does not.
Routing Protocol Overview
Routing is defined as the process of finding a path from source to destination in the network. Routing protocols are used to maintain routing tables; these tables maintain an up to date list of destination networks, and the paths to each of these networks. Some of the issues that routing protocols
have are the following: routing table size, control message overhead (table updates), robustness
(packets getting lost, loops, oscillations, etc.), and path optimality.
When designing networks several issues should be considered:
A) Centralized vs. distributed routing tables
B) Source based vs. Hop by Hop.
C) Stochastic vs. Deterministic
D) Single path vs. multiple paths.
E) Dynamic vs. Static tables.
The routing protocols used in these labs determine the best path between networks or subnets by
the use of routing metrics and include:
•
Hop count - Number of intermediate stops a packet makes in the path to its destination.
Passing through the router is a hop count of one.
46
•
•
•
•
•
•
•
Bandwidth- Data carrying capacity of a media. Usually measured in Mbps or some fraction thereof. Also referred to as the "size of the pipe".
Delay - amount of time associated with the use of a particular media. Usually measured
in mSec.
Reliability - Value assigned to each media indicating the probability of the data being delivered. Usually expressed as a fractional value; some number divided by 255.
Load - Dynamic value indicating the utilization of a media. Usually expressed as a fractional value; some number divided by 255.
MTU - Maximum transmission unit. The largest size data unit for a particular media.
Cost - Arbitrary value indicating the charge for using this interface. Usually expressed as
an integer value and assigned to an outgoing interface.
Ticks - Arbitrary value associated with delay for using the link or interface. The precise
value is 1/18th of a second.
•
RIP characteristics
RIP (Routing Information Protocol) is specified by RFC 1058. RIP was released with BSD Unix
as "routed". RIP is a distance vector routing protocol. It uses Hop count as the metric. The
maximum allowable hop count is 15. Routing updates are broadcast every 30 seconds.
IGRP' characteristics
Interior Gateway Protocol (IGRP) is a proprietary-distance vector routing protocol
developed by Cisco. The protocol uses a combination of variables to determine the metric. The
variables can include:
• Bandwidth Delay
• Load
• Reliability
• MTU
IGRP sends routing updates at 90-second intervals.
EIGRP characteristics
Enhanced Interior Gateway Protocol (EIGRP) has the following characteristics:
• Incorporates rapid convergence.
• Sends incremental updates.
• Supports Hierarchical topology.
• Does not require hierarchical addressing.
• Unifies routing using an integrated mode.
• Supports address extension techniques.
During discovery the first "Hello" packet triggers a full update on that interface.
Subsequent updates contain only changes and not a full table update. A dual algorithm
guarantees that there will be no routing loops within the network and that all routing tables will
contain consistent information. The Dual algorithm utilizes a technique similar to the spanning
algorithm used by bridges. The routing table entries contain the best path to reach any destina-
47
tion. Alternate paths are also calculated; these alternate paths are referred to as "logical successors". In case of a topological change, traffic will be seamlessly re-routed via the logical successor.
In short EIGRP saves on routing update traffic; it integrates multi-protocol traffic-reducing
WAN overhead; distinguishes paths by bandwidth and eliminates duplicate efforts.
Routing Protocol Overviews
The following information was downloaded from the Cisco website and can he found at www.cisco.com.
Routing Information Protocol (RIP)
The Routing Information Protocol (RIP) is a distance-vector protocol that uses hop count
as its metric. RIP is widely used for routing traffic in the global Internet and is an interior gateway protocol (IGP), which means that it performs routing within a single autonomous system.
Exterior gateway protocols, such as the Border Gateway Protocol (BGP), perform routing between different autonomous systems. The original incarnation of RIP was the Xerox protocol,
GWINFO. A later version, known as routed, shipped with Berkeley Standard Distribution (BSD)
Unix in 1982. RIP itself evolved as an Internet routing protocol, and other protocol suites use
modified versions of RIP. The AppleTalk Routing Table Maintenance Protocol (RTMP) and the
Banyan VINES Routing Table Protocol (RTP), for example, both are based on the Internet Protocol (IP) version of RIP. The latest enhancement to RIP is the RIP 2 specification, which allows
more information to be included in RIP packets and provides a simple authentication mechanism.
IP RIP is formally defined in two documents: Request For Comments (RFC) 1058 and 1723.
RFC 1058 (1988) describes the first implementation of RIP, while RFC 1723 (1994) updates
RFC 1058. RFC 1058 enables RIP messages to carry more information and security features.
This chapter summarizes the basic capabilities and features associated with RIP. Topics include
the routing-update process, RIP routing metrics, routing stability, and routing timers.
Routing Updates
RIP sends routing-update messages at regular intervals and when the network topology
changes. When a router receives a routing update that includes changes to an entry, it updates
its routing table to reflect the new route. The metric value for the path is increased by one, and
the sender is indicated as the next hop. RIP routers maintain only the best route (the route
with the lowest metric value) to a destination. After updating its routing table, the router immediately begins transmitting routing updates to inform other network routers of the change.
These updates are sent independently of the regularly scheduled updates that RIP routers
send.
RIP Routing Metric
RIP uses a single routing metric (hop count) to measure the distance between the source and a
destination network. Each hop in a path from source to destination is assigned a hop-count value,
48
which is typically I. When a router receives a routing update that contains a new or changed destination-network entry, the router adds one to the metric
value indicated in the update and enters the network in the routing table. The IP address of the
sender is used as the next hop. RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. The
maximum number of hops in a path is 15. If a router receives a routing update that contains a
new or changed entry, and if increasing the metric value by one causes the metric to be infinity
(that is, 16), the network destination is considered unreachable.
RIP Stability Features
To adjust for rapid network-topology changes, RIP specifies a number of stability features that
are common to many routing protocols. RIP, for example, implements the split-horizon and holddown mechanisms to prevent incorrect routing information from being propagated. In addition,
the RIP hop-count limit prevents routing loops from continuing indefinitely.
RIP Timers
RIP uses numerous timers to regulate its performance. These include a routing-update tinier, a
route timeout, and a route flush tinier. The routing-update timer clocks the interval between periodic routing updates. Generally, it is set to 30 seconds; with a small random number of seconds
added each time the timer is reset to prevent collisions. Each routing-table entry has a routetimeout timer associated with it. When the route-timeout timer expires, the route is marked invalid but is retained in the table until the route-flush timer expires.
Packet Formats
The following section focuses on the IP RIP and IP RIP 2 packet formats illustrated in Figure 5
and 6. Each illustration is followed by descriptions of the fields illustrated.
RIP Packet Format
Figure 5 illustrates the IP RIP packet format.
Figure 21 IP RIP packet consists of nine fields.
49
The following descriptions summarize the IP RIP packet-format fields illustrated in Figure 21:
Command---Indicates whether the packet is a request or a response. The request asks that a
router send all or part of its routing table. The response can be an unsolicited regular routing update or a reply to a request. Responses contain routing table entries. Multiple RIP packets are
used to convey information from large routing tables.
• Version Number – Specifies the RIP version used. This field can signal different potentially incompatible versions
• Zero---Not used.
• Address-Family Identifier (AFI - Specifies the address family used. RIP is designed to
carry routing information for several different protocols. Each entry has an address-family
identifier to indicate the type of address being specified. The AFI for IP is 2.
• Address - Specifies the IP address for the entry.
• Metric---Indicates how many internetwork hops (routers) have been traversed in the trip
to the destination. This value is between 1 and 15 for a valid route, or 16 for an unreachable
route.
Note Up to 25 occurrences of the AFI, address, and metric fields are permitted in a single IP RIP
packet. (Up to 25 destinations can be listed in a single RIP packet.)
RIP 2 Packet Format
The RIP 2 specification (described in RFC 1723) allows more information to be included in RIP
packets and provides a simple authentication mechanism. Figure 6 shows the IP RIP 2 packet
format.
Figure 22 IP RIP 2 packet consists of fields similar to those of an IP RIP packet.
The following descriptions summarize the IP RIP 2 packet format fields illustrated in figure 22:
Command---Indicates whether the packet is a request or a response. The request asks that a
router send all or a part of its routing table. The response can be an unsolicited regular routing
update or a reply to a request. Responses contain routing-table entries. Multiple RIP packets are
used to convey information from large routing tables.
•
•
•
Version---Specifies the RIP version used. In a RIP packet implementing any of the RIP 2
fields or using authentication, this value is set to 2.
Unused---Value set to zero.
Address-Family Identifier (AFI)---Specifies the address family used. RIP is designed to
carry routing information for several different protocols. Each entry has an addressfamily identifier to indicate the type of address specified. The address-family identifier
for IP is 2. If the AFI for the first entry in the message is 0xFFFF, the remainder of the
entry contains authentication information. Currently, the only authentication type is sim50
•
•
•
•
•
ple password.
Route Tag---Provides a method for distinguishing between internal routes (learned by
RIP) and external routes (learned from other protocols).
IP Address---Specifies the IP address for the entry.
Subnet Mask---Contains the subnet mask for the entry. If this field is zero, no subnet
mask has been specified for the entry.
Next Hop---Indicates the IP address of the next hop to which packets for the entry should
be forwarded.
Metric---Indicates how many internetwork hops (routers) have been traversed in the trip
to the destination. This value is between 1 and 15 for a valid route, or 16 for an unreachable route.
Note: Up to 25 occurrences of the AFI, address, and metric fields are permitted in a single IP
RIP packet. That is, up to 25 routing table entries can be listed in a single RIP packet. If the AFI
specifies an authenticated message, only 24 routing table entries can be specified.
Internal Gateway Routing protocol (IGRP)
IGRP is a protocol that allows a number of gateways to coordinate their routing. Its goals are
• stable routing even in very large or complex networks. No routing loops should occur,
even as transients.
• fast response to changes in network topology
• low overhead. That is, IGRP itself should not use more bandwidth than what is actually
needed for its task.
• It splitting traffic among several parallel routes when they are of roughly equal desirability.
• taking into account error rates and level of traffic on different paths
• the ability to handle multiple "types of service" with a single set of information.
The current implementation of IGRP handles routing for TCP/IP. However, the basic design is
intended to be able to handle a variety of protocols. During the last few years, routing has suddenly become a more difficult problem than it used to be. A few years ago, protocols such as RIP
were sufficient to handle most real networks However, growth in the Internet and decentralization of control of its structure, have now resulted in a system of networks that is nearly beyond
our capabilities to manage. Similar situations are occurring in large corporate networks as well.
IGRP is one tool intended to help attack this problem. No one tool is going to solve all routing
problems. Conventionally the routing problem is broken into several pieces. Protocols such as
IGRP are called "internal gateway protocols" (IGPs). They are intended for use within a single
set of networks, either under a single management or closely coordinated managements. Such
sets of networks are connected by "external gateway protocols" (EGPs). An IGP is designed to
keep track of a good deal of detail about network topology. Priority in designing an IGP is placed
on producing optimal routes and responding quickly to changes. An EGP is intended to protect
one system of networks against errors or intentional misrepresentation by other systems. Priority
in designing an EGP is on stability and administrative controls. Often it is sufficient for an EGP
to produce a reasonable route, rather than the optimal route. In fact, there are features in Cisco's
implementation that allow IGRP to be used as an EGP in some circumstances. However, the em51
phasis in its design is on use as an IGP. IGRP has some similarities to older protocols such as
Xerox's Routing Information Protocol, Berkeley's RIP, and Dave Mills' Hello. It differs from
these protocols primarily in being designed for larger and more complex networks. Section 4
gives a more detailed comparison with RIP, which is the most widely used of the older generation of protocols. Like these older protocols, IGRP is a distance vector protocol. In such a protocol, gateways exchange routing information only with adjacent gateways. This routing information contains a summary of information about the rest of the network. It can be shown mathematically that all of the gateways taken together are solving an optimization problem by what
amounts to a distributed algorithm. Each gateway only needs to solve part of the problem, and it
only has to receive a portion of the total data.
The major alternative is a class of algorithms referred to as SPF (shortest- path first). These are
based on a flooding technique, where every gateway is kept up to date about the status of every
interface on every other gateway. Each gateway independently solves the optimization problem
from its point of view using data for the entire network. There are advantages to each approach.
In some circumstances SPF may be able to respond to changes more quickly. In order to prevent
routing loops, IGRP has to ignore new data for a few minutes after certain kinds of changes. Because SPF has information directly from each gateway, it is able to avoid these routing loops.
Thus it can act on new information immediately. However, SPF has to deal with substantially
more data than IGRP, both in internal data structures and in messages between gateways. Thus
SPF implementations can be expected to have higher overhead than IGRP implementations,
other things being equal.
The Routing Problem
IGRP is intended for use in gateways connecting several networks. We assume that the
Networks use packet-based technology. In effect the gateways act as packet switches. When a
system connected to one network wants to send a packet to a system on a different network, it
addresses the packet to a gateway. If the destination is on one of the networks connected to the
gateway, the gateway will forward the packet to the destination. If the destination is more distant,
the gateway will forward the packet to another gateway that is closer to the destination. Gateways use routing tables to help them decide what to do with packets. Here is a simple example
routing table. (Addresses used in the examples are IP addresses taken from Rutgers University.
Note that the basic routing problem is similar for other protocols as well. This description will
assume that IGRP is being used for routing IP.)
52
Table 7 Sample Routing Table
network
gateway
interface
128.6.4
128.6.5
none
none
128.6.21
128.6.4.1
128.121
128.6.5.4
10
128.6.5.4
ethernet
ethernet
ethernet
ethernet
ethernet
0
1
0
1
1
(Actual IGRP routing tables have additional information for each gateway, as we will see.) This
gateway is connected to two Ethernets, called 0 and 1. They have been given IP network numbers
(actually subnet numbers) 128.6.4 and 128.6.5. Thus packets addressed for these specific networks
can be sent directly to the destination, simply by using the appropriate Ethernet interface. There
are two nearby gateways, 128.6.4.I and 128.6.5.4. Packets for networks other than 128.6.4 and
128.6.5 will be forwarded to one or the other of those gateways. The routing table indicates which
gateway should be used for which network. For example, packets addressed to a host on network
10 should be forwarded to gateway 128.6.5.4. One hopes that this gateway is closer to network 10,
i.e. that the best path to network 10 goes through this gateway. The primary purpose of IGRP is allow the gateways to build and maintain routing tables like this.
Summary of IGRP
As mentioned above, IGRP is a protocol that allows gateways to build up their routing
table by exchanging information with other gateways. A gateway starts out with entries for all of
the networks that are directly connected to it. It gets information about other networks by exchanging routing updates with adjacent gateways. In the simplest case, the gateway will find one
path that represents the best way to get to each network. A path is characterized by the next
gateway to which packets should be sent, the network interface that should be used, and metric
information. Metric information is a set of numbers that characterize how good the path is. This
allows the gateway to compare paths that it has heard from various gateways and decide which
one to use. There are often cases where it makes sense to split traffic between two or more paths.
IGRP will do this whenever two or more paths are equally good. The user can also configure it to
split traffic when paths are almost equally good. In this case more traffic will be sent along the
path with the better metric. The intent is that traffic can be split between a 9600 bps line and a
19200
BPS line, and the 19200 line will get roughly as much traffic as the 9600 BPS line. The metric used by IGRP includes:
• the topological delay time
• the bandwidth of the narrowest bandwidth segment of the path
• the channel occupancy of the path
• the reliability of the path
Topological delay time is the amount of time it would take to get to the destination along that
path, assuming an unloaded network. Of course there is additional delay when the network is
loaded. However, load is accounted for by using the channel occupancy figure, not by attempting
to measure actual delays. The path bandwidth is simply the bandwidth in bits per second of the
slowest link in the path. Channel occupancy indicates how much of that bandwidth is currently in
53
use. It is measured, and will change with load. Reliability indicates the current error rate. It is the
fraction of packets that arrive at the destination undamaged. It is measured.
Although they are not used as part of the metric, two addition pieces of information are
passed with it: hop count and MTU. The hop count is simply the number of gateways that a
packet will have to go through to get to the destination. MTU is the maximum packet size that
can be sent along the entire path without fragmentation. (That is, it is the minimum of the MTUs
of all the networks involved in the path.) Based on the metric information, a single "composite
metric" is calculated for the path. The composite metric combines the effect of the various metric
components into a single number representing the "goodness" of that path. It is the composite
metric that is actually used to decide on the best path.
Periodically each gateway broadcasts its entire routing table (with some censoring because of the split horizon rule) to all adjacent gateways. When a gateway gets this broadcast
from another gateway, it compares the table with its existing table. Any new destinations and
paths are added to the gateway's routing table. Paths in the broadcast are compared with existing paths. If a new path is better, it may replace the existing one. Information in the broadcast
is also used to update channel occupancy and other information about existing paths. This general procedure is similar to that used by all distance vector protocols. It is referred to in the
mathematical literature as the Bellman-Ford algorithm. For a detailed development of the basic procedure, see RFC 1058, which describes RIP, an older distance vector protocol.
In IGRP, the general Bellman-Ford algorithm is modified in three critical aspects. First, instead of a simple metric, a vector of metrics is used to characterize paths. Second, instead of
picking a single path with the smallest metric, traffic is split among several paths, whose metrics
fall into a specified range. Third, several features are introduced to provide stability in situations
where the topology is changing.
The best path is selected based on a composite metric:
[(K1 / Be) + (K2 * Dc)] r
Where:
KI, K2 = constants
Be = unloaded path bandwidth x (I - channel occupancy)
Dc = topological delay
r = reliability.
The path having the smallest composite metric will be the best path. Where there are multiple paths to the same destination, the gateway can route the packets over more than one path.
This is done in accordance with the composite metric for each data path. For instance, if one path
has a composite metric of 1 and another path has a composite metric of 3; three times as many
packets will be sent over the data path having the composite metric of 1. However, only paths
whose composite metrics are with a certain range of the smallest composite metric will be used.
K1 and K2 indicate the weight to be assigned to bandwidth and delay. These will depend upon
the "type of service". For example, interactive traffic would normally place a higher weight on
delay, and file transfer on bandwidth.
There are two advantages to using a vector of metric information. The first is that it provides the ability to support multiple types of service from the same set of data. The second advantage is improved accuracy. When a single metric is used, it is normally treated as if it were a
delay. Each link in the path is added to the total metric. If there is a link with a low bandwidth, it
is normally represented by a large delay. However, bandwidth limitations don't really cumulate
the way delays do. By treating bandwidth as a separate component, it can be handled correctly.
Similarly, load can be handled by a separate channel occupancy number.
54
I/3
IGRP provides a system for interconnecting computer networks which can stably handle
a general graph topology including loops. The system maintains full path metric information, i.e.,
it knows the path parameters to all other networks to which any gateway is connected. Traffic
can be distributed over parallel paths and multiple path parameters can be simultaneously computed over the entire network.
55
Enhanced Internal Gateway Routing Protocol (EIGRP)
EIGRP is an enhanced version of IGRP. The same distance vector technology found in
IGRP is also used in EIGRP, and the underlying distance information remains unchanged. The
convergence properties and the operating efficiency of this protocol have improved significantly.
This allows for an improved architecture while retaining existing investment in IGRP.
The convergence technology is based on research conducted at SRI International, (see references
[I] and [2]). The Distributed Update Algorithm (DUAL) is the algorithm used to obtain loopfreedom at every instant throughout a route computation. This allows all routers involved in a
topology change to synchronize at the same time. Routers that are not affected by topology
changes are not involved in the recomputation. The convergence time with DUAL rivals that of
any other existing routing protocol.
EIGRP has been extended to be network-layer-protocol-independent, thereby allowing
DUAL to support other protocol suites.
How Does EIGRP Work?
EIGRP has four basic components:
•
•
•
•
Neighbor discovery/recovery
Reliable Transport Protocol
DUAL finite state machine
Protocol dependent modules
Neighbor discovery/recovery is the process that routers use to dynamically learn of other routers
on their directly attached networks. Routers must also discover when their neighbors become unreachable or inoperative. This process is achieved with low overhead by periodically sending
small Hello packets. As long as Hello packets are received, a router can determine that a
neighbor is alive and functioning. Once this is determined, the neighboring routers can exchange
routing information.
The Reliable Transport Protocol is responsible for guaranteed, ordered delivery of EIGRP
packets to all neighbors. It supports intermixed transmission of multicast or unicast packets.
Some EIGRP packets must be transmitted reliably and others need not. For efficiency, reliability
is provided only when necessary. For example, on a multi-access network that has multicast capabilities, such as Ethernet, it is not necessary to send Hellos reliably to all neighbors individually. EIGRP sends a single multicast Hello with an indication in the packet informing the receivers that the packet need not be acknowledged. Other types of packets, such as Updates, require
acknowledgment and this is indicated in the packet. The reliable transport has a provision to send
multicast packets quickly when there are unacknowledged packets pending. This helps ensure
that convergence time remains low in the presence of varying speed links.
56
The DUAL finite state machine embodies the decision process for all route computations.
It tracks all routes advertised by all neighbors. The distance information, known as a metric, is
used by DUAL to select efficient loop-free paths. DUAL selects routes to be inserted into a routing table based on feasible successors. A successor is a neighboring router used for packet forwarding that has a least cost path to a destination that is guaranteed not to be part of a routing
loop. When there are no feasible successors but there are neighbors advertising the destination, a
recomputation must occur. This is the process where a new successor is determined. The amount
of time it takes to recompute the route affects the convergence time. Even though the recomputation is not processor-intensive, try to avoid recomputation if it is not necessary. When a topology
change occurs, DUAL will test for feasible successors. If there are feasible successors, it uses
any it finds in order to avoid any unnecessary recomputation. Feasible successors will be defined
in more detail later.
The protocol dependent modules are responsible for network layer, protocol-specific requirements. For example, the IP-EIGRP module is responsible for sending and receiving EIGRP
packets that are encapsulated in IP. IP-EIGRP is responsible for parsing EIGRP packets and informing DUAL of the new information received. IP-EIGRP asks DUAL to make routing decisions and the results of which are stored in the IP routing table. IP-EIGRP is responsible for redistributing routes learned by other IP routing protocols.
EIGRP Concepts
This section describes Cisco's EIGRP implementation. Both data structures and the DUAL concepts are discussed.
Neighbor Table
Each router maintains state information about adjacent neighbors. When newly discovered
neighbors are learned, the address and interface of the neighbor is recorded. This information is
stored in the neighbor data structure. The Neighbor Table holds these entries. There is one
Neighbor Table for each protocol-dependent module. When a neighbor sends a Hello, it advertises a HoldTime. The HoldTime is the amount of time a router treats a neighbor as reachable
and operational. In other words, if a Hello packet isn't heard within the HoldTime, the HoldTime
expires. When the HoldTime expires, DUAL is informed of the topology change.
The Neighbor Table entry also includes information required by the reliable transport mechanism. Sequence numbers are employed to match acknowledgments with data packets. The last
sequence number received from the neighbor is recorded so out-of-order packets can be detected.
A transmission list is used to queue packets for possible retransmission on a per-neighbor basis.
Round trip timers are kept in the neighbor data structure to estimate an optimal retransmission
interval.
57
Topology Table
The Topology Table is populated by the protocol-dependent modules and acted upon by the
DUAL finite state machine. It contains all destinations advertised by neighboring routers. Associated with each entry is the destination address and a list of neighbors that have advertised the
destination. For each neighbor, the advertised metric is recorded. This is the metric that the
neighbor stores in its routing table. If the neighbor is advertising this destination, it must be using
the route to forward packets. This is an important rule that distance vector protocols must follow.
Also associated with the destination is the metric that the router uses to reach the destination.
This is the sum of the best advertised metric from all neighbors plus the link cost to the best
neighbor. This is the metric that the router uses in the routing table and to advertise to other
routers.
Feasible Successors
A destination entry is moved from the Topology Table to the routing table when there is a feasible successor. All minimum cost paths to the destination form a set. From this set, the neighbors
that have an advertised metric less than the current routing table metric are considered feasible
successors.
Feasible successors are viewed by a router as neighbors that are downstream with respect to the
destination. These neighbors and the associated metrics are placed in the forwarding table.
When a neighbor changes the metric it has been advertising or a topology change occurs in the
network, the set of feasible successors may have to be re-evaluated. However, this is not categorized as a route recomputation.
Route States
A Topology Table entry for a destination can have one of two states. A route is considered in the Passive state when a router is not performing a route recomputation. The route is in
Active state when a router is undergoing a route recomputation. If there are always feasible successors, a route never has to go into Active state and avoids a route recomputation.
When there are no feasible successors, a route goes into Active state and a route recomputation occurs. A route recomputation commences with a router sending a Query packet to all
neighbors. Neighboring routers can either Reply if they have feasible successors for the destination or optionally return a Query indicating that they are performing a route recomputation.
While in Active state, a router cannot change the next-hop neighbor it is using to forward packets. Once all replies are received for a given Query, the destination can transition to Passive State
and a new successor can be selected. When a link to a neighbor which is the only feasible successor goes down, all routes through that neighbor commence a route recomputation and enter
the Active state.
58
Packet Formats
EIGRP uses five packet types:
• Hello/Acks
• Updates
• Queries
• Replies
• Requests
As stated earlier, Hellos are multicast for neighbor discovery/recovery. They do not require
acknowledgment. A Hello with no data is also used as an Acknowledgment. Acks are always
sent using a unicast address and contain a non-zero acknowledgment number. Updates are used
to convey reachability of destinations. When a new neighbor is discovered, Update packets are
sent so the neighbor can build up its Topology Table. In this case, Update packets are unicast. In
other cases, such as a link cost change, Updates are multicast. Updates are always transmitted
reliably.
Queries and Replies are sent when destinations go into Active state. Queries are always multicast unless they are sent in response to a received Query. In this case, it is unicast back to the
successor that originated the Query. Replies are always sent in response to Queries to indicate to
the originator that it does not need to go into Active state because it has feasible successors. Replies are unicast to the originator of the Query. Both Queries and Replies are transmitted reliably.
Request packets are used to get specific information from one or more neighbors. Request
packets are used in route server applications. They can be multicast or unicast. Requests are
transmitted unreliably.
Route Tagging
EIGRP has the notion of internal and external routes. Internal routes are ones that have
been originated within an EIGRP autonomous system (AS). Therefore, a directly attached network that is configured to run EIGRP is considered an internal route and is propagated with this
information throughout the EIGRP AS. External routes are ones that have been learned by another routing protocol or reside in the routing table as static routes. These routes are tagged individually with the identity of their origination.
External routes are tagged with the following information:
• The router ID of the EIGRP router that redistributed the route.
• The AS number where the destination resides.
• A configurable administrator tag.
• Protocol ID of the external protocol.
• The metric from the external protocol.
• Bit flags for default routing.
As an example, suppose there is an AS with three border routers. A border router is one that
runs more than one routing protocol. The AS uses EIGRP as the routing protocol. Let's say two
of the border routers, BR1 and BR2, use OSPF and the other, BR3, uses RIP.
Routes learned by one of the OSPF border routers, BR1, can be conditionally redistributed
into EIGRP. This means that EIGRP running in BR1 will advertise the OSPF routes within its
own AS. When it does so, it will advertise the route and tag it as an OSPF learned route with a
59
metric equal to the routing table metric of the OSPF route. The router-id will be set to BR1. The
EIGRP route will propagate to the other border routers. Let's say that BR3, the RIP border router,
also advertises the same destinations as BR1. Therefore BR3, redistributes the RIP routes into
the EIGRP AS. BR2, then, has enough information to determine the AS entry point for the route,
the original routing protocol used, and the metric. Further, the network administrator could assign tag values to specific destinations when redistributing the route. BR2 can use any of this information to I) use the route 2) or re-advertise it back out into OSPF.
Using EIGRP route tagging can give a network administrator flexible policy controls and
help customize routing. Route tagging is particularly useful in transit autonomous systems where
EIGRP would typically interact with an inter-domain routing protocol that implements more
global policies. This combines for very scalable policy based routing.
Compatibility Mode
EIGRP provides compatibility and seamless interoperation with IGRP routers. This is
important so users can take advantage of the benefits s of both protocols. The compatibility features do not require users to have a flag day to enable EIGRP. EIGRP can be enabled in strategic
places carefully without disruption to IGRP performance.
There is an automatic redistribution mechanism used so IGRP routes are imported into
EIGRP and vice versa. Since the metrics for both protocols are directly translatable, they are easily comparable as if they were routes that originated in their own AS. In addition, IGRP routes
are treated as external routes in EIGRP so the tagging capabilities are available for custom tuning.
IGRP routes will take precedence over EIGRP routes by default. This can be changed
with a configuration command that does not require the routing processes to restart.
Configuration example
60
61
ECE 467
Lab 3
Frame Relay
In Lab 3 the student will get familiarized with Frame Relay. In order to do this the students will have to build several Local Area Networks (using the knowledge build on Lab I), and
they will have to connect these Networks using Frame Relay. They will also have to use the
knowledge gained in Lab 2 in order to route between the sites. The diagram in figure 23 depicts
the network the students will build.
IP
Figure 23 Lab 3 Frame Relay Network diagram
The physical layer connections will be done using Serial ports. However for this lab the
routers outside the cloud will be Data Terminal Equipment (DTE) devices, and the Router inside
the Cloud will act as a Data computer Equipment (DCE) device. To accomplish this we will use
serial to V.35 DTE cables directly connected to a Serial to V.35 DCE cable (please see figure 24
for connection example).
The router in the cloud represents the Wide Area Network (WAN) - please refer to
figure 23. This router will act as the Frame Relay switch. This router will be responsible for providing the clock to the routers at the edge. This router will also be responsible for the Frame
Relay Switching, which is VC-to-VC switching accomplished at the Data link layer. The Router
in the cloud will not be operating at the Network layer. The Network-to-Network layer communication will occur at the edge routers, please refer to figure 3.
62
Figure 24 DTE to DCE Physical Connection example.
Figure 25 Frame Relay Data Link and Network Layer Connectivity
63
It is important to note the following when configuring the devices in this lab:
A. It is important to note that the default Frame Relay encapsulation is a Cisco's proprietary
encapsulation. In the lab this will not be a problem, however in the real world more than
likely you would have to use Internet Engineering Task Force (IETF) encapsulation. You
might want to test both scenarios.
B. Make sure the right cables are connected to the appropriate interface. The DTE cables
must be connected the DTE device (router outside the cloud), and the DCE cable must be
connected to the DCE router (router inside the cloud). Failure to do so will result in inoperable links.
C. We will be using IP as our Network layer protocol. Each Serial Interface will need an IP
address. In order to maximize Address space a subnet mask of 255.255.255.252 will be
used on all the serial interfaces. Careful address planning should be taken in order to
avoid network errors. Remember the DCE router will not need any IP address; this router
will be acting as a switch.
D. For this Lab the Physical Layer (transmission equipment) needs to be properly cabled.
The DCE router will represent the Wide Area Network, so it is important to note that NO
CSU/DSU will be used in this lab.
E. It is important to note that routing protocols have to be configured in order to connect the
LAN. This implies that the LAN will not be able to communicate with each other unless
routing is enabled. It is left up to the students to select a routing protocol, it is encouraged
that the students choose more than one routing protocol in order to practice with routing
environments.
Frame Relay Overview
The following information was downloaded from the Frame Relay Forum website and can be
found at www.frforum.com
Frame relay technology is based on the concept of using virtual circuits (VCs). VCs are
two-way, software-de-fined data paths between two ports that act as private line re-placements in
the network. While today there are two types of frame relay connections, switched virtual circuits (SVCs) and permanent virtual circuits (PVCs), PVCs were the original service offering. As
a result, PVCs were more commonly used, but SVC products and services are growing in popularity. A more detailed discussion of SVCs and their benefits occurs in Chapter 3. For now, let's
discuss the basic differences between PVCs and SVCs.
Using PVCs
PVCs are set up by a network operator - whether a private net-work or a service provider - via a
network management system. PVCs are initially defined as a connection between two sites or
endpoints. New PVCs may be added when there is a demand for new sites, additional bandwidth,
alternate routing, or when new applications require existing ports to talk to one another. PVCs
are fixed paths, not available on demand or on a call-by-call basis. Although the actual path
taken through the network may vary from time to time, such as when automatic rerouting takes
64
place, the beginning and end of the circuit will not change. In this way, the PVC is like a dedicated point-to-point circuit. PVCs are popular because they provide a cost-effective alternative
to leased lines. Provisioning PVCs requires thorough planning, a knowledge of traffic patterns,
and bandwidth utilization. There are fixed lead times for installation which limit the flexibility of
adding service when required for short usage periods.
The Frame Relay Header and DLCI
Now that we know about virtual circuits, and the fundamental differences between PVCs and
SVCs, let's take a look at the basic structure of a frame relay frame and how it accommodates
other technologies. In the most popular synchronous protocols, data is carried across a communications line in frames which are similar in structure, as shown in Figure 26.
Figure 26 Basic Frame Structure
65
In a frame relay frame, user data packets are not changed in any way. Frame relay simply
adds a two-byte header to the frame. Figure 5 shows the frame relay frame structure and its
header in more detail
Figure 27 Frame Relay Frame Header
For now, let's look at the largest portion of the header, the DLCI. The remaining six bits
of the frame relay header are discussed in the next chapter. The frame relay header contains a 10bit number, called the Data Link Connection Identifier (DLCI). The DLCI is the frame relay virtual circuit number (with local significance) which corresponds to a particular destination. (In the
case of LAN-WAN internetworking, the DLCI denotes the port to which the destination LAN is
attached.) As shown in Figure 28, the routing tables at each intervening frame relay switch in the
private or carrier frame relay network route the frames to the proper destination. Note: In the figures illustrating frame relay networks, the user devices are often shown as LAN routers, since
this is a common frame relay application. They could also be LAN bridges, hosts, front end
processors, FRADs or any other device with a frame re-lay interface.
66
Figure 28 Frame Relay Example
The DLCI allows data coming into a frame relay switch (often called a node) to be sent across
the network using a simple, three-step process:
1. Check the integrity of the frame using the Frame Check Sequence (FCS) - if it indicates
an error, discard the frame.
2. Look up the DLCI in a table - if the DLCI is not defined for this link, discard the frame
Relay the frame toward its destination by sending it out the port or trunk specified in the table.
Simple Rule: If there is a problem, discard the data
In order to simplify frame relay as much as possible, one simple rule exists: if there is any
problem with a frame, simply discard it. There are two principal reasons why frame relay data
might be discarded:
• detection of errors in the data
• congestion (the network is overloaded)
But how can the network discard frames without destroying the integrity of the communications?
The answer lies in the existence of intelligence in the endpoint devices, such as PCs, workstations, and hosts. These endpoint devices operate with multilevel protocols which detect and recover from loss of data in the network. Incidentally, this concept of using intelligent up-per layer
protocols to make up for a backbone network is not a new idea. The Internet relies on this
method to ensure reliable communication across the network.
67
Summary
The basic flow of data in a frame relay net-work can best be described in a series of key points:
• Data is sent through a frame relay network using a data link connection identifier (DLCI),
which specifies the frame's destination.
• If the network has a problem handling a frame due to line errors or congestion, it simply
discards the frame.
• The frame relay network does no error correction; instead, it relies on the higher layer
protocols in the intelligent user devices to recover by retransmitting the lost frames.
• Error recovery by the higher layer protocols, although automatic and reliable, is costly in
terms of delay, processing and bandwidth; thus, it is imperative that the network minimize the occurrence of discards.
• Frame relay requires lines with low error rates to achieve good performance.
• On clean lines, congestion is by far the most frequent cause of discards; thus, the network's ability to avoid and react to congestion is extremely important in determining network performance.
68
Configuration example (Serial Port configuration only)
69
70
ECE 467
Lab 4
Asynchronous Transfer Method (ATM)
In Lab 4 the student will get familiarized with Asynchronous Method Transfer (ATM). In
order to do this the students will have to build several Local Area Networks (using the knowledge learned in Lab I), the students will have to connect these Networks using Serial links (using
the knowledge learned in Lab 2), and the core will be ATM. They will also have to use the
knowledge learned in Lab 2 in order to route between the sites. The diagram in figure 30 depicts
the network the students will build.
Figure 29 Lab 4 Asynchronous Transfer Method
For this lab the ATM links will use two interfaces, a DS3 Interface (45 Mbps), and an OC3 Interface (155Mbps). The physical layer connections for the ATM links will be done with a Coaxial
cable for the DS3 interface and a Fiber Optic cable for the OC3 connection. To connect to the
rest of the routers the students will use Serial ports. The ATM links will act as an ATM core,
however it should be noted that the core would be an IP over ATM core and not a Switching
71
ATM Core. For this lab the students will build Virtual Channel Circuits (VCCs). These VCCs
will be based on the ATM Forum standard ATM Adaptation Layer 5 (AAL5). The Class of service will be non-real timevariable bit rate (nrt-VBR), the UPC parameters used will be Sustained Cell Rate and Peak cell
rate. There will be no policing. Since ATM VBR-nrt does not have now control, and this will be
an IP over ATM transport link, it will rely on TCP for its flow control mechanism. The VCCs
will be configured as Point-to-Point connections.
The diagram in figure 2 depicts the physical layer connectivity between the routers; the serial
connectivity has been omitted since it was covered in earlier labs.
Figure 30 ATM Connectivity Example
The router in the cloud in figure 30 represents the Wide Area Network ATM backbone.
This router will act as the ATM "switch" routing IP traffic over ATM VC's. The router in the
cloud will be operating at the Network layer, since it has to look at the IP layer to router traffic,
however it will use ATM as the Data link layer transport.
It is important to note the following when configuring the devices in this lab:
A. It is important to note that the edge routers can be connected to the ATM core using the
serial ports. The students can use either a Point-to-Point (PPP) connection or a Frame Relay connection. If frame relay is selected it is important to remember the Frame Relay encapsulation being used.
B. In the case of Frame Relay make sure the right cables are connected to the appropriate interface. The DTE cables must be connected the DTE device (router
72
C. outside the cloud), and the DCE cable must be connected to the DCE router (router inside
the cloud). Failure to do so will result in inoperable links. In the case of PPP make sure
the right cable is used (DTE), and that the CSU/DSU are properly configured, one should
provide clock and the other should receive it.
D. We will be using IP as our Network layer protocol. Each Serial Interface (PPP), each
frame Relay VC, and each ATM VCC will need an IP address, all of these connections
will be act as point-to-point terminations. In order to maximize address space a subnet
mask of 255.255.255.252 will be used on all the serial interfaces. Careful address planning should be taken in order to avoid network errors.
E. For this Lab the Physical Layer (transmission equipment) needs to be properly cabled.
Make sure that for the ATM backbone you connect transmit on one router and receive on
the other router. Make sure to provide the physical layer characteristics on the DS3 and
OC3 interfaces.
F. In order to properly configure the ATM VCs, you will need to provide the logical mapping (VPI/VVCI mapping). You will also need to specify the ATM Adaptation Layer (5)
and the UPC parameters (SCR and PCR), for more information please refer to the ATM
Overview in the next section.
G. It is important to note that routing protocols have to be configured in order to connect the
LAN. This implies that the LAN will not be able to communicate with each other unless
routing is enabled. It is left up to the students to select a routing protocol, it is encouraged
that the students choose more than one routing protocol in order to practice with routing
environments.
ATM Network Design Overview
The following information was downloaded from the Cisco's website and can he found at
www.cisco.com For A TM Detailed information please visits the ATM Forum site for the latest
specifications, this site is located at : www.atmforum.com.
Designing ATM internetwork
This chapter describes current Asynchronous Transfer Mode (ATM) technologies that network
designers can use in their networks today. It also makes recommendations for designing nonATM networks so that those networks can take advantage of ATM in the future without sacrificing current investments in cable.
This chapter focuses on the following topics:
• ATM overview
• Cisco's ATM WAN solutions
ATM Defined
ATM is an evolving technology designed for the high-speed transfer of voice, video, and
data through public and private networks in a cost-effective manner. ATM is based on the efforts
73
of Study Group XVIII of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly the Consultative Committee for International Telegraph and
Telephone [CCITT]) and the American National Standards Institute (ANSI) to apply very largescale integration (VLSI) technology to the transfer of data within public networks. Officially, the
ATM layer of the Broadband Integrated Services Digital Network (BISDN) model is defined by
CCITT I.361. Current efforts to bring ATM technology to private networks and to guarantee interoperability between private and public networks is being done by the ATM Forum, which was
jointly founded by Cisco Systems, NET/ADAPTIVE, Northern Telecom, and Sprint in 1991.
Role of ATM in Internetworks
Today, 90 percent of computing power resides on desktops, and that power is growing
exponentially. Distributed applications are increasingly bandwidth-hungry, and the emergence of
the Internet is driving most LAN architectures to the limit. Voice communications have increased significantly with increasing reliance on centralized voice mail systems for verbal communications. The internetwork is the critical tool for information flow. Internetworks are being
pressured to cost less yet support the emerging applications and higher number of users with increased performance.
To date, local and wide-area communications have remained logically separate. In the
LAN, bandwidth is free and connectivity is limited only by hardware and implementation cost.
The LAN has carried data only. In the WAN, bandwidth has been the overriding cost, and such
delay-sensitive traffic as voice has remained separate from data. New applications and the economics of supporting them, however, are forcing these conventions to change.
The Internet is the first source of multimedia to the desktop and immediately breaks the
rules. Such Internet applications as voice and real-time video require better, more predictable
LAN and WAN performance. In addition, the Internet also necessitates that the WAN recognize
the traffic in the LAN stream, thereby driving LAN/WAN integration.
Multiservice Networks
ATM has emerged as one of the technologies for integrating LANs and WANs. ATM can
support any traffic type in separate or mixed streams, delay-sensitive traffic, and nondelaysensitive traffic, as shown in Figure 32.
Figure 31 ATM Support of various traffic types
74
ATM can also scale from low to high speeds. It has been adopted by all the industry's
equipment vendors, from LAN to private branch exchange (PBX). With ATM, network designers can integrate LANs and WANs, support emerging applications with economy in the enterprise, and support legacy protocols with added efficiency.
TDM Network Migration
In addition to using ATM to combine multiple networks into one multiservice network, network designers are deploying ATM technology to migrate from TDM networks for the following
reasons:
• To reduce WAN bandwidth cost
• To improve performance
• To reduce downtime
Reduced WAN Bandwidth Cost
The Cisco line of ATM switches provide additional bandwidth through the use of voice
compression, silence compression, repetitive pattern suppression, and dynamic bandwidth allocation. The Cisco implementation of ATM combines the strengths of TDM---whose fixed time
slots are used by telephone companies to deliver voice without distortion---with the strengths of
packet-switching data networks---whose variable size data units are used by computer networks,
such as the Internet, to deliver data efficiently. While building on the strengths of TDM, ATM
avoids the weaknesses of TDM (which wastes bandwidth by transmitting the fixed time slots
even when no one is speaking) and PSDNs (which cannot accommodate time-sensitive traffic,
such as voice and video, because PSDNs are designed for transmitting bursty data). By using
fixed-size cells, ATM combines the isochronicity of TDM with the efficiency of PSDN.
Improved Performance
ATM offers improved performance through performance guarantees and robust WAN traffic
management that support the following capabilities:
• Large buffers that guarantee Quality of Service (QoS) for bursty data traffic and demanding multimedia applications
• Per-virtual circuit (VC) queuing and rate scheduling
• Feedback---congestion notification
Reduced Downtime
ATM offers high reliability, thereby reducing downtime. This high reliability is available because of the following ATM capabilities:
• The capability to support redundant processors, port and trunk interfaces, and power supplies
• The capability to rapidly reroute around failed trunks
Integrated Solutions
75
The trend in internetworking is to provide network designers greater flexibility in solving
multiple internetworking problems without creating multiple networks or writing off existing
data communications investments. Routers can provide a reliable, secure network and act as a
barrier against inadvertent broadcast storms in the local networks. Switches, which can be divided into two main categories---LAN switches and WAN switches---can be deployed at the
workgroup, campus backbone, or WAN level, as shown in Figure 33.
Figure 32 The Role of ATM Switches in a Network
Underlying and integrating all Cisco products is the Cisco IOS software. The Cisco IOS software
enables disparate groups, diverse devices, and multiple protocols all to be integrated into a highly
reliable and scalable network.
Different Types of ATM Switches
Even though all ATM switches perform cell relay, ATM switches differ markedly in the following ways:
• Variety of interfaces and services that are supported
• Redundancy
• Depth of ATM internetworking software
• Sophistication of traffic management mechanism
Just as there are routers and LAN switches available at various price/performance points with
different levels of functionality, ATM switches can be segmented into the following four distinct
types that reflect the needs of particular applications and markets:
• Workgroup ATM switches
• Campus ATM switches
• Enterprise ATM switches
• Multiservice access switches
76
ATM Overview
Structure of an ATM Network
ATM is based on the concept of two end-point devices communicating by means of intermediate switches. As Figure 6 shows, an ATM network is made up of a series of switches and
end-point devices. The end-point devices can be ATM-attached end stations, ATM-attached
servers, or ATM-attached routers.
Figure 33 Components of an ATM Network
As Figure 34 shows, there are two types of interfaces in an ATM network:
• It User-to-Network Interface (UNI)
• Network-to-Network Interface (NNI)
The UNI connection is made up of an end-point device and a private or public ATM switch.
The NNI is the connection between two ATM switches. The UNI and NNI connections can be
carried by different physical connections.
In addition to the UNI and NNI protocols, the ATM Forum has defined a set of LAN Emulation (LANE) standards and a Private Network to Network Interface (PNNI) Phase 0 protocol.
LANE is a technology network designers can use to internetwork legacy LANs such as Ethernet
and Token Ring with ATM-attached devices. Most LANE networks consist of multiple ATM
switches and typically employ the PNNI protocol. The full PNNI 1.0 specification was released
by the ATM Forum in May 1996. It enables extremely scalable, full function, dynamic multivendor ATM networks by providing both PNNI routing and PNNI signaling. PNNI is based on
UNI 3.0 signaling and static routes. The section "Role of LANE" later in this chapter discusses
ATM LANE networks in detail.
General Operation on an ATM Network
Because ATM is connection-oriented, a connection must be established between two end points
before any data transfer can occur. This connection is accomplished through a signaling protocol
as shown in Figure 35.
77
Figure 34 Establishing a connection in an ATM network.
As Figure 35 shows, for Router A to connect to Router B the following must occur:
1. Router A sends a signaling request packet to its directly connected ATM switch (ATM
Switch 1). This request contains the ATM address of the Router B as well as any QoS
parameters required for the connection.
2. ATM Switch 1 reassembles the signaling packet from Router A, and then examines it.
3. If ATM Switch 1 has an entry for Router B's ATM address in its switch table and it can
accommodate the QoS requested for the connection, it sets up the virtual connection and
forwards the request to the next switch (ATM Switch 2) along the path.
4. Every switch along the path to Router B reassembles and examines the signaling packet,
and then forwards it to the next switch if the QoS parameters can be supported. Each
switch also o sets s up the virtual connection as the signaling packet is forwarded. If any
switch along the path cannot accommodate the requested QoS parameters, the request is
rejected and a rejection message is sent back to Router A.
5. When the signaling packet arrives at Router B, Router B reassembles it and evaluates
the packet. If Router B can support the requested QoS, it responds with an accept message. As the accept message is propagated back to Router A, the switches set up a virtual
circuit. 4
6. Router A receives the accept message from its directly connected ATM switch (ATM
Switch 1), as well as the Virtual path identifier (VPI) and Virtual channel identifier (VCI)
values that it should use for cells sent to Router B. 5
ATM Functional Layers
Just as the Open System Interconnection (OSI) reference model describes how two computers
communicate over a network, the ATM protocol model describes how two end systems communicate through ATM switches. The ATM protocol model consists of the following three func4
A virtual channel is equivalent to a virtual circuit---that is, both terms describe a logical connection between the
two ends of a communications connection. A virtual path is a logical grouping of virtual circuits that allows an ATM
switch to perform operations on groups of virtual circuits.
5
ATM cells consist of five bytes of header information and 48 bytes of payload data. The VPI and VCI fields
in the ATM header are used to route cells through ATM networks. The VPI and VCI fields of the cell header
identify the next network segment that a cell needs to transmit on its way to its final destination.
78
tional layers:
• ATM physical layer
• ATM layer
• ATM adaptation layer
As Figure 36 shows, these three layers correspond roughly to Layer 1 and parts of Layer 2 (such
as error control and data framing) of the OSI reference model.
Figure 35 Relationship of ATM functional layers to the OSI reference model
Physical Layer
The ATM physical layer controls transmission and receipt of bits on the physical medium. It also keeps track of ATM cell boundaries and packages cells into the appropriate type of
frame for the physical medium being used. The ATM physical layer is divided into two parts:
• Physical medium sublayer
• Transmission convergence sublayer
Physical Medium Sublayer
The physical medium sublayer is responsible for sending and receiving a continuous flow
of bits with associated timing information to synchronize transmission and reception. Because it
includes only physical-medium-dependent functions, its specification depends on the physical
medium used. ATM can use any physical medium capable of carrying ATM cells. Some existing
standards that can carry ATM cells are SONET (Synchronous Optical Network)/SDH, DS-3/E3,
100-Mbps local fiber (Fiber Distributed Data Interface [FDDI] physical layer), and 155-Mbps
local fiber (Fiber Channel physical layer). Various proposals for use over twisted-pair wire are
also under consideration.
Transmission Convergence Sublayer
The transmission convergence sublayer is responsible for the following:
•
Cell delineation---Maintains ATM cell boundaries.
79
• Header error control sequence generation and verification---Generates and checks the
header error control code to ensure valid data.
• Cell rate decoupling --- Inserts or suppresses
• Cell rate decoupling ---Inserts or suppresses idle (unassigned)
calls to adapt
the rate of valid ATM cells to the payload capacity of the transmission system. it Transmission frame adaptation---Packages ATM cells into frames acceptable to the particular physical-layer implementation.
• Transmission frame generation and recovery---Generates and maintains the appropriate
physical-layer frame structure.
ATM Layer
The ATM layer establishes virtual connections and passes ATM cells through the ATM network.
To do this, it uses the information contained in the header of each ATM cell. The ATM layer is
responsible for performing the following four basic functions:
• Multiplexing and demultiplexing the cells of different virtual connections. These connections are identified by their VCI and VPI values.
• Translating the values of the VCI and VPI at the ATM switches or cross connects.
• Extracting and inserting the header before or after the cell is delivered to or from the
higher ATM adaptation layer.
• Handling the implementation of a flow control mechanism at the UNI.
ATM Adaptation Layer (AAL)
The AAL translates between the larger service data units (SDUs) (for example, video
streams and data packets) of upper-layer processes and ATM cells. Specifically, the AAL receives packets from upper-level protocols (such as AppleTalk, Internet Protocols [IP], and NetWare) and breaks them into the 48-byte segments that form the payload field of an ATM cell.
Several ATM adaptation layers are currently specified. Table 1 summarizes the characteristics of
each AAL.
Characteristics
AAL1
AAL3/4
AAL4
AAL5
Requires timing between
Yes
source and destination
No
No
No
Data rate
Constant
Variable
Variable
Variable
Connection mode
Connectionoriented
Connectionoriented
Connectionless
Connectionoriented
Traffic types
Voice and circuit
Data
emulation
Data
Data
Table 8 ATM Adapter Layers
80
AAL1
AAL1 prepares a cell for transmission. The payload data consists of a synchronous sample (for example, one byte of data generated at a sampling rate of 125 microseconds). The sequence number field (SN) and sequence number protection (SNP) fields provide the information
that the receiving AALI needs to verify that it has received the cells in the correct order. The rest
of the payload field is filled with enough single bytes to equal 48 bytes.
AAL1I is appropriate for transporting telephone traffic and uncompressed video traffic. It
requires timing synchronization between the source and destination and, for that reason, depends
on a media that supports clocking, such as SONET. The standards for supporting clock recovery
are currently being defined.
AAL3/4
AAL3/4 was designed for network service providers and is closely aligned with Switched Multimegabit Data Service (SMDS). AAL3/4 is used to transmit SMDS packets over an ATM network. The convergence sublayer (CS) creates a protocol data unit (PDU) by prepending a Beginning/End Tag header to the frame and appending a length field as a trailer as shown in Figure 9.
The segmentation and reassembly (SAR) sublayer fragments the PDU and prepends to each PDU
Figure 36 AAL3/4 cell preparation
fragment a header consisting of the following fields:
• Type---Identifies whether the cell is the beginning of a message, continuation of a message, or end of a message.
• Sequence number---Identifies the order in which cells should be reassembled.
• Multiplexing identifier---Identifies cells from different traffic sources interleaved on the
same virtual circuit connection (VCC) so that the correct cells are reassembled at the destination.
The SAR sublayer also appends a CRC-10 trailer to each PDU fragment. The completed SAR
PDU becomes the payload field of an ATM cell to which the ATM layer prepends the standard
ATM header.
81
AAL5
Figure 37 AAL5 cell preparation
AAL5 prepares a cell for transmission as shown in Figure 38.
First, the convergence sublayer of AAL5 appends a variable-length pad and an 8-byte
trailer to a frame. The pad is long enough to ensure that the resulting PDU falls on the 48-byte
boundary of the ATM cell. The trailer includes the length of the frame and a 32-bit CRC computed across the entire PDU, which allows AAL5 at the destination to detect bit errors and lost
cells or cells that are out of sequence.
Next, the segmentation and reassembly segments the CS PDU into 48-byte blocks. Then
the ATM layer places each block into the payload field of an ATM cell. For all cells except the
last cell, a bit in the PT field is set to zero to indicate that the cell is not the last cell in a series
that represents a single frame. For the last cell, the bit in the PT field is set to one. When the cell
arrives at its destination, the ATM layer extracts the payload field from the cell; the SAR
sublayer reassembles the CS PDU; and the CS uses the CRC and the length field to verify that
the frame has been transmitted and reassembled correctly. AAL5 is the adaptation layer used to
transfer most non-SMDS data, such as classical IP over ATM and local-area network (LAN)
emulation.
ATM Addressing
The ATM Forum has adapted the subnetwork model of addressing in which the ATM layer is
responsible for mapping network-layer addresses to ATM addresses. Several ATM address formats have been developed. Public ATM networks typically use E.164 numbers, which are also
used by Narrowband ISDN (N-ISDN) networks. Figure 11 shows the format of private network
ATM addresses. The three formats are Data Country Code (DCC), International Code Designator
(ICD), and Network Service Access Point (NSAP) encapsulated E.164 addresses.
82
Figure 38 ATM address formats
Fields of an ATM Address
The fields of an ATM address are as follows:
• AFI---One byte of authority and format identifier. The AFI field identifies the type of address. The defined values are 45, 47, and 39 for E.164, ICD, and DCC addresses, respectively.
• DCC---Two bytes of data country code.
• DM---One byte of domain specific part (DSP) format identifier.
• AA---Three bytes of administrative authority.
• RD---Two bytes of routing domain.
• Area---Two bytes of area identifier.
• ESL--Six bytes of end system identifier, which is an IEEE 802 Media Access Control
(MAC) address.
• Sel---One byte of Network Service Access Point (NSAP) selector.
• ICD---Two bytes of international code designator.
• E.164---Eight bytes of Integrated Services Digital Network (ISDN) telephone number.
The ATM address formats are modeled on ISO NSAP addresses, but they identify subnetwork point of attachment (SNPA) addresses. Incorporating the MAC address into the ATM
address makes it easy to map ATM addresses into existing LANs.
ATM Media
The ATM Forum has defined multiple standards for encoding ATM over various types of
media. Table 9 lists the framing type and data rates for the various media, including unshielded
twisted-pair (UTP) and shielded twisted-pair (STP) cable.
83
Framing
DS-1
El
DS-3
E3
STS-1
SONET
SIS3C
SDH STM1
SONET
STS12c
SDH STM4
TAXI 4B/5
8B/10B
(Fiber
Channel)
Data Rate
(Mbps)
Multimode Single
Coaxial
Fiber
Mode Fiber Cable
1.544
2.048
45
34
51
UTP-3
UTP-5
STP
D
D
D
D
D
155
D
D
622
D
D
100
D
155
D
D
D
D
Table 9 ATM Physical rates
Because the FDDI chipset standard, TAXI 4B/5B, was readily available, the ATM Forum
encouraged initial ATM development efforts by endorsing TAXI 4B/5B as one of the first ATM
media encoding standards. Today, however, the most common fiber interface is STS3c/STM.
There are two standards for running ATM over copper cable: UTP-3 and UTP-5. The
UTP-5 specification supports 155 Mbps with NRZI encoding, while the UTP-3 specification
supports 51 Mbps with CAP-16 encoding. CAP-16 is more difficult to implement, so, while it
may be cheaper to wire with UTP-3 cable, workstation cards designed for CAP-16-based UTP-3 may
be more expensive and will otter less bandwidth. Because ATM is designed to run over fiber and
copper cable, investments in these media today will maintain their value when networks migrate to
full ATM implementations as ATM technology matures.
84
Configuration example (ATM Port configuration only)
85
APPENDIX
86
Figure 39 Lab 1A initial diagram
87
Figure 40 Lab 1A configuration example
88
Figure 41 Lab 1A pinouts
89
Figure 42 Lab 1b Ethernet configuration
90
Figure 43 Lab 1b configuration example
91
Figure 44 Lab 1b ethernet straight through cable
92
Figure 45 Lab 1b ethernet crossover cable
93
Figure 46 Lab 2a PPP network
94
Figure 47 Lab 2a WAN connectivity
95
Figure 48 Lab 2a Cross connect cable
96
Figure 49 Lab 2b Routing diagram
97
Figure 50 Lab 2b Route redistribution example
98
Figure 51 Lab 2b IGRP routing example
99
Figure 52 Lab 2b IGRP configuration
100
Figure 53 Lab 2b RIP diagram
101
Figure 54 Lab 2b RIP configuration
102
Figure 55 Lab 3 Frame relay diagram
103
Figure 56 Lab 3 Frame relay setup
104
Figure 57 Lab 3 connectivity
105
Figure 58 Lab 4 ATM diagram
106
Figure 59 Lab 4 connectivity
107
Figure 60 Lab 4 ATM pinouts
108
Figure 61 RACAL crossover cable
109
Figure 62 RJ48C crossover cable
110
Figure 63 Cisco cable
111
Figure 64 Ethernet cable
112
Figure 65 Ethernet crossover cable
113
Figure 66 Cisco adapter
114

ECE 467 Network Implementation Lab Manual

Transcription

Similar documents

June 2013 - Goodsoil Credit Union

Map – PDF - K-Days

How to use AlJazira ATM

Fall 2015

MasterMoney® and ATM Card Application

civic place - Update Southlake

Check Cashing Alternatives

FCNB - Student Checking Flyer

Newsletter 04-15.indd

device jackpotting