Ccna PPT2

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Cisco IOS

Cisco technology is built around the CiscoInternetwork Operating System (IOS), which is thesoftware that controls the routing and switchingfunctions of internetworking devices.

A solid understanding of the IOS is essential for anetwork administrator.

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The Purpose of Cisco IOS

As with a computer, a router or switch cannot function without anoperating system. Cisco calls its operating system the Cisco InternetworkOperating System or Cisco IOS.

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Introduction to Routers

A router is a special type of computer. It has the same basic components as a standard desktopPC. However, routers are designed to perform some very specific functions. Just as computersneed operating systems to run software applications, routers need the Internetwork OperatingSystem software (IOS) to run configuration files. These configuration files contain theinstructions and parameters that control the flow of traffic in and out of the routers. The manyparts of a router are shown below:

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Router Memory Components

ROM - Read Only Memory – Bootstrap/POST

FLASH Memory- IOS Images are kept here

- Erasable reprogrammable ROM- Contents are kept on Power down or reload

RAM - Random Access memory

- Routing Tables- Running Configuration- Contents are lost on reboot

NVRAM - Start up configuration

- Configuration Register- Contents are kept on reload

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ROM

Read-Only Memory

ROM has the following characteristics and functions:

Maintains instructions for power-on self test (POST) diagnostics

Stores bootstrap program and basic operating system software

Mini IOS

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RAM

Random Access Memory, also called dynamic RAM (DRAM)

RAM has the following characteristics and functions:

Stores routing tables Holds ARP cache Performs packet buffering (shared RAM) Provides temporary memory for the configuration file of

the router while the router is powered on Loses content when router is powered down or restarted

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NVRAM

Non-Volatile RAM

NVRAM has the following characteristics and functions:

Provides storage for the startup configuration fileRetains content when router is powered down or

restartedConfiguration Register – 16 bit register which decidesboot sequence

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Flash

Flash memory has the following characteristics and functions:

Holds the operating system image (IOS) Allows software to be updated without

removing and replacing chips on the processor Retains content when router is powered down

or restarted Can store multiple versions of IOS software Is a type of electronically erasable,

programmable ROM (EEPROM)

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Interfaces

Interfaces have the following characteristics and functions:

Connect router to network for frame entry and exit Can be on the motherboard or on a separate module

Types of interfaces:

Ethernet Fast Ethernet Serial ISDN BRI Loopback Console Aux

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Router Internal Components

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Router Power-On/Bootup Sequence

1. Perform power-on self test (POST).

2. Load and run bootstrap code.

3. Find the Cisco IOS software.

4. Load the Cisco IOS software.

5. Find the configuration.

6. Load the configuration.

7. Run the configured Cisco IOS software.

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Boot Sequence

ROMMonitorRXBootFLASH

Configuration Register

C-File NVRAM

Y

N

Running

Setup Mode

Checks All interfaces

RAM

1415 13 12 1011 9 8 67 5 4 23 1 0

48 2 1 48 2 1 48 2 1 48 2 1

0 0 0 0

0 0 0 1

0 0 1 0

ROMMonitor

RxBoot

Flash1 1 1 1

0

1

2-15

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After the Post…

After the POST, the following events occur as the router initializes:

Step 1The generic bootstrap loader in ROM executes. A bootstrap is a simple set of instructions thattests hardware and initializes the IOS for operation.

Step 2The IOS can be found in several places. The boot field of the configuration register determinesthe location to be used in loading the IOS.

Step 3The operating system image is loaded.

Step 4The configuration file saved in NVRAM is loaded into main memory and executed one line at atime. The configuration commands start routing processes, supply addresses for interfaces,and define other operating characteristics of the router.

Step 5If no valid configuration file exists in NVRAM, the operating system searches for an availableTFTP server. If no TFTP server is found, the setup dialog is initiated.

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Loading the Cisco IOS Software From Flash Memory

• The flash memory file is decompressed into RAM.

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Loading the Configuration

• Load and execute the configuration from NVRAM.

• If no configuration is present in NVRAM, enter setup mode.

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External Components of a 2600 Router

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Internal Components of a 2600 Router

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Computer/Terminal Console Connection

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HyperTerminal Session Properties

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Establishing aHyperTerminal Session

Take the following steps to connect a terminal to the console port on the router:

First, connect the terminal using the RJ-45 to RJ-45 rollover cable and an RJ-45 to DB-9 or RJ-45 to DB-25 adapter.

Then, configure the terminal or PC terminal emulation software for 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow control.

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Router Command Line Interface

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IOS File System Overview

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Router LED Indicators

Cisco routers use LED indicators to provide status information. Dependingupon the Cisco router model, the LED indicators will vary. An interface LEDindicates the activity of the corresponding interface. If an LED is off whenthe interface is active and the interface is correctly connected, a problemmay be indicated. If an interface is extremely busy, its LED will always beon. The green OK LED to the right of the AUX port will be on after thesystem initializes correctly.

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Router User Interface Modes

The Cisco command-line interface (CLI) uses a hierarchical structure. This structurerequires entry into different modes to accomplish particular tasks.

Each configuration mode is indicated with a distinctive prompt and allows onlycommands that are appropriate for that mode.

As a security feature the Cisco IOS software separates sessions into two accesslevels, user EXEC mode and privileged EXEC mode. The privileged EXEC mode is

also known as enable mode.

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Overview of Router Modes

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Router Modes

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CLI Command Modes

All command-line interface (CLI) configuration changes to a Cisco router are made from the global configuration mode. Other more specific modes are entered depending upon the configuration change that is required.

Global configuration mode commands are used in a router to apply configuration statements that affect the system as a whole.

The following command moves the router into global configuration mode

Router#configure terminal (or config t)Router(config)#

When specific configuration modes are entered, the router prompt changes to indicate the current configuration mode.

Typing exit from one of these specific configuration modes will return the router to global configuration mode. Pressing Ctrl-Z returns the router to all the way back privileged EXEC mode.

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Show Version Command

wg_ro_a#show version

Cisco Internetwork Operating System Software

IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fc1)

Copyright (c) 1986-1999 by cisco Systems, Inc.

Compiled Mon 08-Feb-99 18:18 by phanguye

Image text-base: 0x03050C84, data-base: 0x00001000

ROM: System Bootstrap, Version 11.0(10c), SOFTWARE

BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE(fc1)

wg_ro_a uptime is 20 minutes

System restarted by reload

System image file is "flash:c2500-js-l_120-3.bin"

(output omitted)

--More--

Configuration register is 0x2102

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Viewing the Configuration

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show running-config and show startup-config Commands

wg_ro_c#show startup-config

Using 1359 out of 32762 bytes

!

version 12.0

!

-- More --

wg_ro_c#show running-configBuilding configuration...

Current configuration:!version 12.0!

-- More --

In NVRAMIn RAM

• Displays the current and saved configuration

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Configurations in two locations - RAM and NVRAM.

•The running configuration is stored in RAM.•Any configuration changes to the router are made to therunning-configuration and take effect immediately after thecommand is entered.•The startup-configuration is saved in NVRAM and is loaded intothe router's running-configuration when the router boots up.• To save the running-configuration to the startup configuration,type the following from privileged EXEC mode (i.e. at the"Router#" prompt.)

Router# copy run start

Saving Configurations

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Command Abbreviation

Show Configuration – sh conf

Configure Terminal – conf t

Line auxillary – line aux

Line console – line con

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Configuring a Router’s Name

A router should be given a unique name as one of the firstconfiguration tasks.

This task is accomplished in global configuration mode usingthe following commands:

Router(config)#hostname GatesGates(config)#

As soon as the Enter key is pressed, the prompt changes fromthe default host name (Router) to the newly configured hostname (which is Gates in the example above).

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Settingthe Clockwith Help

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Message Of The Day (MOTD)

A message-of-the-day (MOTD) banner can be displayed on all

connected terminals.

Enter global configuration mode by using the command config t

Enter the command

banner motd # Welcome to Gates Training #.

Save changes by issuing the command copy run start

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Privileged Mode Command

# show startup-config

# show running-config

# show version

# show flash

# show interfaces

# show interfaces s 0

# show history

# show terminal

# terminal history size 25

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Password

Passwords restrict access to routers. Passwords should always be configured for virtual terminal lines and the console line. Passwords are also used to control access to privileged EXEC mode so that only authorized users may make changes to the configuration file.

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Passwords

There are five passwords for Router

Privileged Mode Password – 2

Line Console Password

Auxiliary Port Password

Telnet Password

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Privileged Mode Password

Gates(config)# enable password gates

Encrypted privilege mode password

Gates(config)# enable secret gates1

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Line Password

Gates(config)# line console 0

Gates(config)# password cisco

Gates(config)# login

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Aux Port Password

Gates(config)# line aux 0



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Connecting to Aux Port

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Configuring a Telnet Password

A password must be set on one or more of the virtualterminal (VTY) lines for users to gain remote access to therouter using Telnet.

Typically Cisco routers support five VTY lines numbered 0through 4.

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Telnet Password

Gates(config)# line vty 0 4



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Encrypting Passwords

Only the enable secret password is encrypted by default

Need to manually configure the user-mode and enablepasswords for encryption

To manually encrypt your passwords, use the servicepassword-encryption command

Router#config t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#service password-encryption

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Disable Passwords

Gates(config)# no enable password

Gates(config)# no enable secret

For the Console

Gates(config)# line con 0

Gates(config)# no password

Gates(config)# line vty 0 4

Gates(config)# no password

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LAB – Interface Configuration

S0 S0E010.0.0.1

10.0.0.2

30.0.0.220.0.0.120.0.0.2 30.0.0.1

A

S0

E0

40.0.0.2

40.0.0.1

B

S1

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Descriptions

Setting descriptions on an interface is helpful to the administrator

Only locally significant

R1(config)#int e0

R1(config-if)#description Sales Lan

R1(config-if)#int s0

R1(config-if)#desc Wan to Mumbai

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Configuring Interfaces

An interface needs an IP Address and a Subnet Mask to be configured. All interfaces are “shutdown” by default. The DCE end of a serial interface needs a clock rate.R1#config t

R1(config)#int e0

R1(config)#Description Connoted to Host

R1(config-if)#ip address 10.0.0.1 255.0.0.0

R1(config-if)#no shutdown

R1(config-if)#exitR1(config)#interface serial 0R1(config-if)#ip address 20.0.0.1 255.255.255.0

R1(config-if)# bandwidth 64R1(config-if)#clock rate 64000 (required for serial DCE only) R1(config-if)#no shutdownR1(config-if)#exitR1(config)#exitR1#

On new routers, Serial 1 would be just Serial 0/1 and e0 would be f0/0.

s = serial e = Ethernet f = fast Ethernet

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DCE DTE

To find out DCE or DTE

#Show controllers s 0

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Viewing Configuration

To Check the status of interface

#Show IP interface brief

or

#Sh IP int brief

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Saving and Erasing Configurations

To copy RAM to NVRAM

# copy run startup-config

To remove all configuration

# erase startup-config

# reload

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Objectives

Upon completion of this chapter, you will be able to complete the following tasks:

Distinguish the use and operation of static and dynamic routes

Configure and verify a static route

Identify how distance vector IP routing protocols such as RIP and IGRP operate on Cisco routers

Enable Routing Information Protocol (RIP)

Enable Interior Gateway Routing Protocol (IGRP)

Verify IP routing with show and debug commands

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Routing

The process of transferring data from one local areanetwork to another

Layer 3 devicesRouted protocol Enables to forward packet from one

router to another – Ex – IP, IPXRouting protocol sends and receives routing

information packets to and from other routers – Ex -RIP, OSPF , IGRP

Routing protocols gather and share the routinginformation used to maintain and update routingtables.

That routing information is in turn used to route arouted protocol to its final destination

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Routing

From

Raj

House #213, 4th Street

Jayanagar, Bangalore

To

Ram

House #452, 2nd Street

Dadar, Mumbai

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To route, a router needs to know:

Destination addresses

Sources it can learn from

Possible routes

Best route

What is Routing?

172.16.1.010.120.2.0

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What is Routing? (cont.)

NetworkProtocol

DestinationNetwork

ConnectedLearned

10.120.2.0172.16.1.0

Exit Interface

E0S0

Routed Protocol: IP

Routers must learn destinations that are not directly connected

172.16.1.010.120.2.0

E0S0

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Route Types

Static routing - network administrator configuresinformation about remote networks manually. They areused to reduce overhead and for security.

Dynamic routing - information is learned from otherrouters, and routing protocols adjust routesautomatically.

Because of the extra administrative requirements, staticrouting does not have the scalability of dynamic routing.

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IP Routing Process

Step-by-step what happens when Host A wants tocommunicate with Host B on a different network

A user on Host A pings Host B’s IP address.

E0 E1

10.0.0.1

10.0.0.2A B 20.0.0.2

20.0.0.1

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LAB – Interface Configuration

S0 S0E010.0.0.1

10.0.0.2

30.0.0.220.0.0.120.0.0.2 30.0.0.1

A

S0

E0

40.0.0.2

40.0.0.1

B

S1

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Test The Connection

• Host A can ping router R1 and R2

• To enable Host A to Ping Host B we need to configure Routes

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IP Routing

The different types of routing are:

Static routing

Default routing

Dynamic routing

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Static Routes

Benefits

No overhead on the router CPU

No bandwidth usage between routers

Adds security

Disadvantage

Administrator must really understand the internetwork

If a network is added to the internetwork, the

administrator has to add a route to it on all routers

Not feasible in large networks

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– R1(config)# iproute DestAddress SNM Nexthop address

R1(config)#ip route network [mask] {address | interface}[distance] [permanent]

Static Route Configuration

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ip route The command used to create the static route. destination_network The network you’re placing in the routing table. mask The subnet mask being used on the network. next-hop_address The address of the next-hop router that will receive the packet

and forward it to the remote network. This is a router interface that’s on a directlyconnected network.

exitinterface You can use it in place of the next-hop address if you want, but it’sgot to be on a point-to-point link, such as a WAN

administrative_distance By default, static routes have an administrativedistance of 1 (or even 0 if you use an exit interface instead of a next-hop address)

permanent If the interface is shut down, or the router can’t communicate to thenext-hop router, the route will automatically be discarded from the routing table.Choosing the permanent option keeps the entry in the routing table no matter whathappens.

ip route [destination_network] [mask] [next-hop_address or exitinterface]

[administrative_distance] [permanent

Static Route Configuration

R1(config)#ip route 30.0.0.0 255.0.0.0 20.0.0.2

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LAB – Static Route Configuration

S0 S0E010.0.0.1

10.0.0.2

30.0.0.220.0.0.120.0.0.2 30.0.0.1

A

S0

E0

40.0.0.2

40.0.0.1

B

S1

R1# config tR1(config)#ip route 30.0.0.0 255.0.0.0 20.0.0.2R1(config)#ip route 40.0.0.0 255.0.0.0 20.0.0.2



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Verifying StaticRoute Configuration

After static routes are configured it is important to verify thatthey are present in the routing table and that routing isworking as expected.

The command show running-config is used to view theactive configuration in RAM to verify that the static route wasentered correctly.

The show ip route command is used to make sure that thestatic route is present in the routing table.

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S0 S0E010.0.0.1

10.0.0.2

30.0.0.220.0.0.120.0.0.2 30.0.0.1

A

S0

E0

40.0.0.2

40.0.0.1

B

S1

R1# config tR1(config)#no ip route 30.0.0.0 255.0.0.0 20.0.0.2R1(config)#no ip route 40.0.0.0 255.0.0.0 20.0.0.2



Removing IP Route

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Default Routes

• Can only use default routing on stub networks

• Stub networks are those with only one exit path out ofthe network

• The only routers that are considered to be in a stubnetwork are R1 and R3

S0S0E0

E010.0.0.1

10.0.0.2 40.0.0.2

20.0.0.1

20.0.0.2

30.0.0.1

A B

S0S1

30.0.0.2

40.0.0.1

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Stub Network

ip route 0.0.0.0 0.0.0.0 172.16.2.2

Default Routes

172.16.2.1

SO

172.16.1.0

B172.16.2.2

NetworkA B

This route allows the stub network to reach all known networks beyond router A.

10.0.0.0

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Configuring Default Routes

Default routes are used to route packets with destinations that do not match any of the other routes in the routing table.

A default route is actually a special static route that uses this format:

ip route 0.0.0.0 0.0.0.0 [next-hop-address | outgoing interface]

This is sometimes referred to as a “Quad-Zero” route.

Example using next hop address:

Router(config)#ip route 0.0.0.0 0.0.0.0 172.16.4.1

Example using the exit interface:

Router(config)#ip route 0.0.0.0 0.0.0.0 s0/0

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S0S0E0

E010.0.0.1

10.0.0.2 40.0.0.2

20.0.0.1

20.0.0.2

30.0.0.1

A B

S0S1

30.0.0.2

40.0.0.1

LAB Configuration

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Default Route LAB Configuration

S0S0E0

E010.0.0.1

10.0.0.2 40.0.0.2

20.0.0.1

20.0.0.2

30.0.0.1

A B

S0S1

30.0.0.2

40.0.0.1

R1# config tR1(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.2

R3# config tR3(config)#ip route 0.0.0.0 0.0.0.0 30.0.0.1


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What is a Routing Protocol?

Routing protocols areused betweenrouters to determinepaths and maintainrouting tables.

Once the path isdetermined a router canroute a routed protocol.

NetworkProtocol

DestinationNetwork

ConnectedRIP

IGRP

10.120.2.0172.16.2.0172.17.3.0

Exit Interface

E0S0S1

Routed Protocol: IPRouting protocol: RIP, IGRP

172.17.3.0

172.16.1.010.120.2.0

E0S0

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Autonomous System

AS 2000

AS 3000

IGP

Interior Gateway Protocols are

used for routing decisions

within an Autonomous System.

Exterior Gateway

Protocols are used

for routing between

Autonomous Systems

EGP

AS 1000

An Autonomous System (AS) is a group of IP networks, which has asingle and clearly defined routing policy.Group of routers which can exchange updatesAS are identified by numbers

Fig. 48 IGP and EGP (TI1332EU02TI_0004 The Network Layer, 67)

All Routing protocols are categorized as IGP or EGP

Routing Categories

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IGP

Interior Gateway Protocol

(IGP)

Exterior Gateway

Protocol (EGP)

EGP

EGP

EGP

Interior Gateway Protocol

(IGP)

AS 1000

AS 2000

AS 3000

Fig. 49 The use of IGP and EGP protocols (TI1332EU02TI_0004 The Network Layer, 67)

Routing Categories

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An autonomous system is a collection of networks under acommon administrative domain.

IGPs operate within an autonomous system.

EGPs connect different autonomous systems.

Autonomous Systems: Interior or Exterior Routing Protocols

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Types or Classes of Routing Protocols

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Distance Vector

RIP V1

IGRP

RIP V2

Link state

OSPF

Hybrid

EIGRP

Types or Classes of Routing Protocols

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Classful Routing Overview

Classful routing protocols do not include the subnet mask with theroute advertisement.

Within the same network, consistency of the subnet masks isassumed.

Summary routes are exchanged between foreign networks.

Examples of classful routing protocols:

RIP Version 1 (RIPv1)

IGRP

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Classless Routing Overview

Classless routing protocols include the subnet mask withthe route advertisement.

Classless routing protocols support variable-lengthsubnet masking (VLSM) and subnetting

Examples of classless routing protocols:


EIGRP

OSPF

IS-IS

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• Routers pass periodic copies of routing table to neighbor routers and accumulate distance vectors.

Distance Vector Routing Protocols

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Distance Vector

Uses Bellman Ford Algorithm

It needs to find out the shortest path from one network to other

How to determine which path is best?

192.168.10.1192.168.20.1

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Distance Vector

There are two Distance Vector Protocol, Both uses different metric

RIP – Hops

IGRP - Composite

192.168.10.1

192.168.20.1

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Distance Vector

DV protocol are known as Routing by rumor RIP uses only Hop count RI routing table metric for 192.168.20.1 network will be

3 2

192.168.10.1

192.168.20.1

0

1

1

2

2

3R1

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Distance Vector

192.168.10.1

192.168.20.1

56 kbps

1 Mbps1 Mbps

1 Mbps

56 kbps

• IGGRP uses bandwidth and delay as Metric• RI routing table metric for 192.168.20.1 network will be

– 30– 60

R110

10

10

30 30192.168.10.1

92

Routing Loops

A network problem in which packets continue to be routed in an endless circle

93

• Routers discover the best path to destinations from each neighbor.

Sources of Information and Discovering Routes

94

• Each node maintains the distance from itself to each possible destination network.

Inconsistent Routing Entries

95

• Slow convergence produces inconsistent routing.

Inconsistent Routing Entries (Cont.)

96

• Router C concludes that the best path to network 10.4.0.0 is through router B.


97

• Router A updates its table to reflect the new but erroneous hop count.


98

Hop count for network 10.4.0.0 counts to infinity.

Count to Infinity

99

• Packets for network 10.4.0.0 bounce (loop) between routers B and C.

Routing Loops

100

• Define a limit on the number of hops to prevent infinite loops.

Defining a Maximum

101

Maximum Hop Count

• One way of solving routing loop problem is to define amaximum hop count.

• RIP permits a hop count of up to 15, so anything thatrequires 16 hops is deemed unreachable

• The maximum hop count will control how long it takesfor a routing table entry to become invalid

102

• It is never useful to send information about a route back in the direction from which the original information came.

Split Horizon

103

Split Horizon

Solution to the Routing Loop problem

Split Horizon is a rule that routinginformation cannot be sent back in thedirection from which it was received

Had split horizon been used in ourexample, Router B would not haveincluded information about network10.4.0.0 in its update to Router C.

104

Route Poisoning

• Route Poisoning. Usually used in conjunction with splithorizon

• Route poisoning involves explicitly poisoning a routingtable entry for an unreachable network

• Once Router C learned that network 10.4.0.0 wasunavailable it would have immediately poisoned theroute to that network by setting its hop count to therouting protocol’s infinity value

• In the case of RIP, that would mean a hop count of 16.

105

Triggered Updates

New routing tables are sent to neighboring routers on a regular basis.

RIP updates occur every 30 seconds

However a triggered update is sent immediately in response to somechange in the routing table.

The router that detects a topology change immediately sends an updatemessage to adjacent routers that, in turn, generate triggered updatesnotifying their adjacent neighbors of the change.

Triggered updates, used in conjunction with route poisoning, ensure thatall routers know of failed routes.

106

Triggered Updates Graphic

107

Holddowns

• Holddowns are a technique used to ensure that a route recentlyremoved or changed is not reinstated by a routing table updatefrom another route

• Holddown prevents regular update messages from reinstating aroute that is going up and down (called flapping)

• Holddowns prevent routes from changing too rapidly by allowingtime for either the downed route to come back up

• Holddowns make a router wait a period of time before accepting anupdate for a network whose status or metric has recently changed

108

Solution: Holddown Timers

109

Pinhole Congestion

192.168.10.1

192.168.20.1

1Mbps 1Mbps

56kbps

56kbps

110

RIP Timers

• Route update timer Sets the interval (typically 30 seconds)between periodic routing updates

• Route invalid timer Determines the length of time (180 seconds)before a router determines that a route has become invalid

• Holddown timer This sets the amount of time during whichrouting information is suppressed. This continues until either anupdate packet is received with a better metric or until the holddowntimer expires. The default is 180 seconds

• Route flush timer Sets the time between a route becoming invalidand its removal from the routing table (240 seconds).

111

Routing Information Protocol (RIP)

Routing Information Protocol (RIP) is a true distance-vector routingprotocol.

It sends the complete routing table out to all active interfaces every30 seconds

RIP only uses hop count to determine the best way to a remotenetwork

It has a maximum allowable hop count of 15 AD is 120 Bellman-ford algorithm Works well in small networks, but it’s inefficient on large networks RIP version 1 uses only classful routing, which means that all

devices in the network must use the same subnet mask RIP version 2 does send subnet mask information with the route

updates. This is called classless routing.

112

Router Configuration

The router command starts a routing process.

The network command is required because it enables therouting process to determine which interfaces participate inthe sending and receiving of routing updates.

An example of a routing configuration is:

Gates(config)#router ripGates(config-router)#network 172.16.0.0

The network numbers are based on the network classaddresses, not subnet addresses or individual host addresses.

113

RIP Configuration

S0S0

E0E0

192.168.10.1

A B

S0S1

R1# config tR1(config)# )#router ripR1(config)#network 192.168.10.0R1(config)#network 192.168.20.0

R2# config tR2(config)#router ripR2(config)#network 192.168.20.0R2(config)#network 192.168.30.0192.168.10.2

192.168.20.1

192.168.20.2

192.168.30.1

192.168.30.2 192.168.40.1

192.168.40.2

R3# config tR3(config)# )#router ripR3(config)#network 192.168.30.0R3(config)#network 192.168.40.0

114

Verifying RIP Configuration

115

Displaying the IP Routing Table

116

debug ip rip Command

117

Passive Interface

Passive-interface command prevents RIP updatebroadcasts from being sent out a defined interface, butsame interface can still receive RIP updates

R1#config t

R1(config)#router rip

R1(config-router)#network 192.168.10.0

R1(config-router)#passive-interface serial 0

Passive-interface command depends upon the routingprotocol

RIP router with a passive interface will still learn aboutthe networks advertised by other routers

EIGRP, a passive-interface will neither send nor receiveupdates.

118


R1# config tR1(config)# )#router ripR1(config)#network 192.168.10.0R1(config)#network 192.168.20.0R1(config)#version 2

119

Exercise - RIP Version 2 Configuration

S0S0

E0E0

192.168.0.16/29

A B

S0S1

192.168.0.4/30 192.168.0.8/30

192.168.0.32/28

1. Find out the IP Address and SNM of each interfaces

120


S0S0

E0E0

192.168.0.18255.255.255.248

A B

S0S1

192.168.0.17255.255.255.248

192.168.0.5255.255.255.252

192.168.0.6255.255.255.252

192.168.0.9255.255.255.252

192.168.0.10255.255.255.252

192.168.0.33255.255.255.240

192.168.0.34255.255.255.240

121


S0S0

E0E0

192.168.0.16/29

A B

S0S1

192.168.0.4/30 192.168.0.8/30

192.168.0.32/28R2# config tR2(config)#router ripR2(config)#network 192.168.0.4R2(config)#network 192.168.0.8R2(config)#version 2



122© 2002, Cisco Systems, Inc. All rights reserved. 122

Enabling IGRP

123

CISCO Proprietary

More scalable than RIP

Sophisticated metric

Introducing IGRP

124

Bandwidth

Delay

Reliability

Load

MTU

IGRP Composite Metric

125

IGRP

Some of the IGRP key design characteristics emphasize the following:

It is a distance vector routing protocol.

Routing updates are broadcast every 90 seconds.

Bandwidth, load, delay and reliability are used to create a

composite metric.

The main difference between RIP and IGRP configuration isthat when you configure IGRP, you supply the autonomoussystem number. All routers must use the same number in orderto share routing table information.

126

IGRP Vs RIP

128

Configuring IGRP

129

IGRP Configuration

S0S0

E0E0

192.168.10.1

A B

S0S1

R1# config tR1(config)# )#router igrp 10R1(config)#network 192.168.10.0R1(config)#network 192.168.20.0

R2# config tR2(config)#router igrp 10R2(config)#network 192.168.20.0R2(config)#network 192.168.30.0192.168.10.2

192.168.20.1

192.168.20.2

192.168.30.1

192.168.30.2 192.168.40.1

192.168.40.2

R3# config tR3(config)# )#router igrp 10R3(config)#network 192.168.30.0R3(config)#network 192.168.40.0

130

Verifying the IGRP Routing Tables

LabA#sh ip route

[output cut]

I 192.168.50.0 [100/170420] via 192.168.20.2, Serial0/0

I 192.168.40.0 [100/160260] via 192.168.20.2, Serial0/0

I 192.168.30.0 [100/158360] via 192.168.20.2, Serial0/0

C 192.168.20.0 is directly connected Serial0/0

C 192.168.10.0 is directly connected, FastEthernet0/0

• The I means IGRP-injected routes. The 100 in [100/160360] is theadministrative distance of IGRP. The 160,360 is the compositemetric. The lower the composite metric, the better the route.

• To delete all routes

clear ip route

131

Debug Commands

debug ip igrp events Command

summary of the IGRP routing information that is running on the network.

debug ip igrp transactions Command

shows message requests from neighbor routers asking for an update and the broadcasts sent from your router toward that neighbor router.

no debug all – to turn off all debug

Ccna PPT2

Engineering

routing packets

router bs routing table

routing decision

inconsistent routing

new routing table

incorrect routing information

router c updates

failure of network