CCNA 2 v3.0 Module 7

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28 Οκτ 2013 (πριν από 3 χρόνια και 11 μήνες)

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CCNA 2 v3.0 Module 7

Distance Vector Routing
Protocols

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Objectives


Distance vector routing


RIP


IGRP

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Distance vector routing

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Distance Vector Updates

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Problem: Routing Loops


Routing loops can occur when
inconsistent routing tables are not
updated due to slow convergence in a
changing network.

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Problem: Counting to Infinity

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Solution: Defining a Maximum for
Infinity

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Solution: Split Horizon

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Solution: Route Poisoning

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Solution: Triggered Updates

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Solution: Holddown Timers

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RIP

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Key Characteristics of RIP

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RIP Commands


Using
router rip

and
network

commands to Enable RIP


Enabling RIP on an IP
-
addressed network


Monitoring IP packet flow using the
show
ip protocol

command


The
show ip route

command

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Configuring RIP

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Using the
ip classless

Command

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RIP Configuration Issues


To reduce routing loops and counting to
infinity, RIP uses

the following
:

Defining

infinity

Split horizon

Route poisoning & poison reverse

Triggered updates

Holddown timers

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The
show ip protocols

Command

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The
show ip route

Command

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Troubleshooting RIP Update Issues


debug ip rip


show ip rip database



show ip protocols {summary}



show ip route



debug ip rip {events}



show ip interface brief

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Preventing Routing Updates through
an Interface

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Load Balancing with RIP

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Administrative Distance

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Integrating Static Route with RIP


A router running RIP can receive a default
route via an update from another router
running RIP.


Another option is for the router to
generate the default route itself.


The administrator can override a static
route with dynamic routing information by
adjusting the administrative distance
values.

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IGRP

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IGRP Features

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IGRP Commands


Using
router igrp

and
network

commands to enable IGRP


Enabling IGRP on an IP
-
addressed
network


Monitoring IP packet flow using the
show
ip protocol

command


The
show ip interfaces

command


The
show ip route

command


The
debug ip rip

command

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IGRP Metrics


Bandwidth


The lowest bandwidth value
in the path



Delay


The cumulative interface delay
along the path



Reliability


The reliability on the link
towards the destination as determined by
the exchange of keepalives



Load


The load on a link towards the
destination based on bits per second


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IGRP Routes:

Interior, System, & Exterior

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IGRP Stability Features


Holddowns, Split horizons, & Poison
-
reverse
updates

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Configuring IGRP

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Migrating RIP to IGRP

1.
Verify existing routing protocol (RIP) on
the routers to be converted.

2.
Configure IGRP on RouterA and RouterB

3.
Enter
show ip protocols

on RouterA
and RouterB

4.
Enter
show ip route

on RouterA and
RouterB

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Verifying IGRP Configuration


Some commands for checking IGRP
configuration are as follows:

show interface
interface

show running
-
config

show running
-
config interface
interface

show running
-
config | begin interface
interface

show running
-
config | begin igrp

show ip protocols

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Troubleshooting IGRP


The following commands are useful when
troubleshooting IGRP:

show ip protocols {summary}

show ip route

debug ip igrp events IGRP protocol
events

debug ip igrp transactions IGRP
protocol transactions

ping

traceroute