ccna chapter 3

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© 2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v.0Ch!"ter # #

Introduction to $yn!mic

%outing Protocol

Routing Protocols andConcepts – Chapter 3


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ITE PC v.0Ch!"ter # 2© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Objectives $escribe the role o& dyn!mic routing "rotocols

Identi&y sever!l '!ys to cl!ssi&y routing "rotocols.

Identi&y !nd describe the metrics used by dyn!mic

routing "rotocols. $etermine the !dministr!tive dist!nce o& ! route !nd

its im"ort!nce in the routing "rocess.


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ITE PC v.0Ch!"ter # (© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Dynamic Routing Protocols


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ITE PC v.0Ch!"ter # © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Dynamic Routing Protocols $yn!mic %outing Protocols)

*$yn!mic!lly sh!re in&orm!tion bet'een routers.

*Autom!tic!lly u"d!te routing t!ble 'hen to"ology ch!nges.

*$etermine best "!th to ! destin!tion.


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ITE PC v.0Ch!"ter # +© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Dynamic Routing Protocols The purpose of a dynamic routing protocol is to)

*$iscover remote net'ors

*-!int!ining u"*to*d!te routing in&orm!tion

*Choosing the best "!th to destin!tion net'ors

*Ability to &ind ! ne' best "!th i& the current "!th is no longer!v!il!ble


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Dynamic Routing Protocols Components of a routing protocol

Algorithm

An !lgorithm is ! &inite list o& ste"s used in !ccom"lishing !t!s.

Routing protocol messagesdiscover neighboring routers, e/ch!nge routing in&orm!tion,!nd m!int!in !ccur!te in&orm!tion !bout the net'or.

Data Structure

Some routing "rotocols use t!bles !ndor d!t!b!ses &or itso"er!tions. This in&orm!tion is e"t in %A-.


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Adv!nt!ges o& dynamic routing

1 Administr!tor h!s less 'or m!int!ining the con&igur!tion'hen !dding or deleting net'ors.

1Protocols !utom!tic!lly re!ct to the to"ology ch!nges.1Con&igur!tion is less error*"rone.

1-ore sc!l!ble, gro'ing the net'or usu!lly does not "resent !"roblem.

$is!dv!nt!ges o& dynamic routing

1%outer resources !re used CP3 cycles, memory !nd linb!nd'idth4.

1-ore !dministr!tor no'ledge is re5uired &or con&igur!tion,veri&ic!tion, !nd troubleshooting.



Dynamic Routing Protocols Adv!nt!ges o& static routing

1-inim!l CP3 "rocessing.

1E!sier &or !dministr!tor to underst!nd.

1E!sy to con&igure.

$is!dv!nt!ges o& static routing

1Con&igur!tion !nd m!inten!nce is time*consuming.

1Con&igur!tion is error*"rone, es"eci!lly in l!rge net'ors.

1 Administr!tor intervention is re5uired to m!int!in ch!nging

route in&orm!tion.1$oes not sc!le 'ell 'ith gro'ing net'ors m!inten!ncebecomes cumbersome.

1%e5uires com"lete no'ledge o& the 'hole net'or &or "ro"erim"lement!tion.


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Classifying Routing Protocols

Dynamic routing protocols !re grou"ed !ccording toch!r!cteristics. E/!m"les include)

*%IP

*I9%P

*EI9%P*:SP;

*IS*IS

*


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Classifying Routing Protocols "ypes of routing protocols)

*#nterior $ate%ay Protocols I9P4

*&'terior $ate%ay Protocols E9P4


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ITE PC v.0Ch!"ter # #(© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Classifying Routing Protocols #nterior $ate%ay Routing Protocols #$P!

*3sed &or routing inside !n !utonomous system = used to route'ithin the individu!l net'ors themselves.

*E/!m"les) %IP, EI9%P, :SP;

&'terior Routing Protocols &$P!*3sed &or routing bet'een !utonomous systems

*E/!m"le)


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I9P) Comparison of Distance (ector = )in* State %outing Protocols

Distance vector

> routes !re !dvertised !s vectors o& dist!nce = direction.

> incom"lete vie' o& net'or to"ology.

>9ener!lly, "eriodic u"d!tes.

)in* state

> com"lete vie' o& net'or to"ology is cre!ted. > u"d!tes !re not "eriodic.


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Classful routingprotocols

$o ?:T send subnet m!sin routing u"d!tes

Classless routingprotocols

$o send subnet m!s in

routing u"d!tes.


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ITE PC v.0Ch!"ter # #7© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Classifying Routing Protocols Convergence is de&ined !s 'hen !ll routers@ routing

t!bles !re !t ! st!te o& consistency


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Routing Protocols +etrics +etric

A v!lue used by ! routing "rotocol to determine 'hichroutes !re better th!n others.


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Routing Protocols +etrics +etrics used in #P routing protocols

*


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Routing Protocols +etrics +etric used &or e!ch

routing "rotocol

%IP * ho" count

I9%P = EI9%P *


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ITE PC v.0Ch!"ter # 2#© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Routing Protocols +etrics )oad balancing

This is the !bility o& ! router to distribute "!cets !mongmulti"le s!me cost "!ths


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Administrative Distance of a Route

Purpose of a metricIt@s ! c!lcul!ted v!lue used to determine the best "!th to !destin!tion

Purpose of Administrative Distance

It@s ! numeric v!lue th!t s"eci&ies the "re&erence o& ! "!rticul!rroute


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ITE PC v.0Ch!"ter # 2(© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public


#dentifying the Administrative Distance A$4 in !routing t!ble

It is the &irst number in the br!cets in the routing t!ble


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Directly connected routes!ve ! de&!ult AD of ,

Static Routes

Administr!tive dist!nce o& ! st!tic route h!s ! default value of

-


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Directly connected routes*Immedi!tely !""e!r in the routing t!ble !s soon !s theinter&!ce is con&igured


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Summary Dynamic routing protocols &ul&ill the &ollo'ing &unctions

*$yn!mic!lly sh!re in&orm!tion bet'een routers

* Autom!tic!lly u"d!te routing t!ble 'hen to"ology ch!nges

*$etermine best "!th to ! destin!tion

Routing protocols are grouped as either

*Interior g!te'!y "rotocols I9P4Or

*E/terior g!te'!y "rotocolsE9P4

"ypes of #$Ps include

*Cl!ssless routing "rotocols * these "rotocols include subnet m!sin routing u"d!tes

*Cl!ss&ul routing "rotocols * these "rotocols do not include subnetm!s in routing u"d!te


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Summary

+etrics !re used by dyn!mic routing "rotocols to c!lcul!te thebest "!th to ! destin!tion.

Administrative distance is !n integer v!lue th!t is used toindic!te ! router@s trust'orthinessD

Components of a routing table include)

*%oute source

*Administr!tive dist!nce

*-etric


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