materi ccnp routing (bgp')

7/26/2019 Materi CCNP Routing (BGP')

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Implementing Cisco IP Routi


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AGENDA

IP Routing Overvie EIGRP OSPF Path Control

BGP IPv6


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BORDER GATEWAYPROTOCOLBGP

Protocol that glues internettogether!


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Routing roto!ol to e"!hange routing in#or$ation %

&i'erent networ() RFC*+,-

RFC*,+6 . I$le$entation reort on BGP

RFC*,++ . Oerational e"erien!e) u)ing BGP

IETF Wor(ing Grou) IDR /Internet0Do$ain Routing . htt.11&atatra!(er2iet#2org1 SIDR /Se!ure IDR . htt.11&atatra!(er2iet#2org1wg1)i&r

AS /Autono$ou) S4)te$3 5)e& to uniuel4 i&enti#4 networ() with a !o$$on routin

BGP Basics
http://datatracker.ietf.org/wg/sidrhttp://datatracker.ietf.org/wg/sidr


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Colle!tion o# networ()

)a$e routing oli!4 Single routing roto!ol 5)uall4 un&er )ingle

owner)hi7 tru)t an&a&$ini)trative !ontrol2

I&enti#4 %4 a uniue AS8u$%er /AS83 , o!tet /-6%it3 integer nu

* o!tet /9,%it3 integer nu/RFC*:;93

Autonomous System


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Range)

< = 6>>9> Original -6%it range 6>>96 = *,;*;6+,;> 9,%it range = RFC*:;9

5)age . < an& 6>>9> re)erve&1!annot %e u)e&

- = 6**;> u%li! /Tel(o$)el?) AS 8u$%er = ,96;93

6**;6 = 6*>-- &o!u$entation uro)e = RFC>9;:

6*>-, = 6>>9* rivate /Tel(o$)el u)e& 6*6:; a) Internal AS nu$%er3

,9*>6 rere)ent 9,%it range in -6%it worl&

6>>96 = 6>>>- &o!u$entation uro)e = RFC>9;:

6>>>, = *,;*;6+,;> u%li!

9,%it range rere)entation )e!i@e& in RFC>9;67 &e@ne) a))tan&ar& notation /an ,


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BGP Basics


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BGP )hare) )o$e !hara!teri)ti!) with )o$e routing

4ou?vealrea&4 )tu&ie& . BGP )uort) LS an& )u$$ariation2 BGP will )en& #ull u&ate) when two router) initiall

neigh%or) an& will )en& onl4 artial u&ate) a#ter t BGP &oe) !reate an& $aintain neigh%or relation)h

e"!hanging route)7 an& (eealive) are )ent to (eerelation)hi alive2

Characteristics


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Ile Router i) )ear!hing the routing ta%le to )ee whether a route e"i)t) to the neigh%or2

ConnectRouter #oun& a route to neigh%or an& ha) !o$lete& three0wa4 TCPan&)ha(e2

!pen sent Oen $e))age )ent7 with ara$eter #or BGP Se))ion2

!pen con"rm Router re!eive& agree$ent on the ara$eter) #or e)ta%li)hing a )e))

Alternativel47 the router goe) into a!tive )tate i# no re)on)e to oen

$e))ageEstablishe Peering i) e)ta%li)he&7 routing %egin)2

BGP States


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Conne!tion Oriente& u)e& TCP ort -+; to !reate n

Sent (eealive) $e))age to $aintain relation)hi On!e the !onne!tion i) e)ta%li)he&7 BGP Sea(er e

route) an& )4n! their ta%le)2 /onl4 at initial ro!e) A#ter initial e"!hange7 BGP Sea(er will onl4 )en& #

u&ate) uon a !hange in the networ( toolog42 8o reuire ro)e!tive neigh%or to %e the )a$e AS

BGP Peering Process


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Be#ore e)ta%li)hing a BGP eer !onne!tion the two neigh%or) $u)t )tan&ar& TCP three0wa4 han&)ha(e an& oen a TCP !onne!tion to o

A#ter the TCP )e))ion i) e)ta%li)he&7 BGP eer) e"!hange) )everal $oen an& !on@r$ !onne!tion ara$eter) an& to )en& BGP routing in

All BGP $e))age) are uni!a)t to the one neigh%or over the TCP !onn

There are #our BGP $e))age t4e).

#ype $% !PEN

#ype &% 'EEPAIE

#ype *% +PDA#E

#ype ,% N!#I-ICA#I!N

BGP .essages #ype


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A#ter the TCP )e))ion i) e)ta%li)he&7 %othneigh%or) )en& Oen $e))age)2

Thi) $e))age i) u)e& to e)ta%li)h !onne!tion)with eer)2

Ea!h neigh%or u)e) thi) $e))age to i&enti#4 it)el#an& to )e!i#4 it) BGP oerational ara$eter)in!lu&ing.

BGP /ersion number/&e#ault) to ver)ion *3

AS number. AS nu$%er o# the originatingrouter7 &eter$ine) i# BGP )e))ion i) EBGP orIBGP2

BGP ienti"er. IP a&&re)) that i&enti@e) theneigh%or u)ing the )a$e $etho& a) OSPF routerID2

!ptional parameter. authenti!ation7$ultiroto!ol )uort an& route re#re)h2

BGP .essages #ype 0 !PEN


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Thi) $e))age t4e i) )ent erio&i!all4 %etween eer) to $ainta!onne!tion) an& veri#4 ath) hel& %4 the router )en&ing the (ee

I# a router a!!et) the ara$eter) )e!i@e& in it) neigh%or?) O$e))age7 it re)on&) with a ee alive2

Su%)euent eealive) are sent e/ery 12 secons%4 Ci)!o &eual to one0thir& the agree&0uon hol& ti$e /-:< )e!on&)32

I# the erio&i! ti$er i) )et to a value o# ero /


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The 5PDATE $e))age) !ontain all the in#or$ation BGP u)e) to !on)t#ree i!ture o# the internetwor(2

5&ate $e))age) a&verti)e) #ea)i%le route)7 with&rawn route)7 or % The three %a)i! !o$onent) o# an 5PDATE $e))age are.

Net3or40ayer Reachability In5ormation (NRI)

Path Attributes

6ithra3n Routes

BGP .essage #ype 0 +pates


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The 8OTIFICATIO8 $e))age i) )ent when BGP &ete!t) an error !on& Peering )e))ion i) ter$inate& an& the TCP i) !onne!tion i) !lo)e&2

The !au)e o# the error !on&ition i) )ent to the eer #or &e%ugging antrou%le)hooting2

BGP .essage #ype 0 Noti"catio


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eBGP

RTA(config)#router bgp 100

RTA(config-router)#neighbor 10.1.1.1 remote-as 200

RTB(config)#router bgp 200

RTB(config-router)#neighbor 10.1.1.2 remote-as 100

RTB. 8ote that the neighbor!o$$an&?) remote0asvalue7 -


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iBGP

RTB(config)#router bgp 200

RTB(config-router)#neighbor 172.16.1.2 remote-as 200

RTB(config-router)#neighbor 172.16.1.2 update-source oopbac! 0

RT"(config)#router bgp 200

RT"(config-router)#neighbor 172.16.1.1 remote-as 200RT"(config-router)#neighbor 172.16.1.1 update-source oopbac! 0

Sin!e the remote0asvalue /,


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IGP7BGP .oels


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Summary o5 the BGP Path Selection Process

BGP )ele!t) onl4 one ath a) the %e)t ath2 When the ath i) )ele!te&7 BGP ut) the )ele!te& ath in it) routing ta%le an& roagate) the ath to it) neigh%or) BGP u)e) the #ollowing !riteria7 in the or&er re)ente&7 to )ele!t a ath #or a &e)tination.

-2 I# the ath )e!i@e) a ne"t ho that i) ina!!e))i%le7 &ro the u&ate

,2 Pre#er the ath with the largest 3eight2

92 I# the weight) are the )a$e7 re#er the ath with the largest local pre5erence2

*2 I# the lo!al re#eren!e) are the )a$e7 re#er the path that 3as originate by BGPrunning on thi) router2

>2 I# no route wa) originate&7 re#er the route that ha) the shortest AS8path2

62 I# all ath) have the )a$e ASath length7 re#er the ath with the lo3est origint4e /where IGP i) lower than Ethan In!o$lete32

+2 I# the origin !o&e) are the )a$e7 re#er the ath with the lo3est .ED attribute2

:2 I# the ath) have the )a$e ED7 re#er the e9ternal pathover the internal ath2

;2 I# the ath) are )till the )a$e7 re#er the ath through the closest IGP neighbor2

-


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To %egin !on@guring a BGP ro!e))7 i))ue the #ollowing #a$iliar !o$$an&. Router(config)#router bgpAS-number

BGP !on@guration !o$$an&) aear on the )ur#a!e to $irror the )4nta" o# #a/#or e"a$le7 RIP7 OSPF3 !o$$an&)2

Although the )4nta" i) )i$ilar7 the #un!tion o# the)e !o$$an&) i) )igni@!antl Note. Ci)!o IOS er$it) onl4 one BGP ro!e)) to run at a ti$e7 thu)7 a route

belong to more than one AS:

BGP E9ample Con"guration


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Router(config-router)#netor! network-number$mas! network-mask%The net3or4!o$$an& i) u)e& with IGPs7 )u!h a) RIP7 to &eter$ine the in

whi!h to )en& an& re!eive u&ate)7 a) well a) whi!h &ire!tl4 !onne!te& nea&verti)e2

owever7 when !on@guring BGP7 the net3or4!o$$an& &oe) nota'e!t winter#a!e) BGP run) on2

In BGP7 the net3or4!o$$an& tell) the BGP ro!e)) 3hat locally learneto a/ertise2 2



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These networks must also exist in the local routers rtable (show ip route), or they will not be sent out in u

You !an u)e the mas4(e4wor& with the net3or4!o$$an&in&ivi&ual )u%net)2

Route) learne& %4 the BGP ro!e)) are roagate& %4 &e#auo#ten @ltere& %4 a routing oli!42



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Router(config-router)#neighbor ip-addressremote-as AS-number

In or&er #or a BGP router to establish a neighbor relationship 3ith anorouter7 4ou $u)t i))ue the thi) !on@guration !o$$an&2

Thi) !o$$an& )erve) to i&enti#4 a eer router with whi!h the lo!al router wa )e))ion2

TheAS-numberargu$ent &eter$ine) whether the neigh%or router i) an EIBGP neigh%or2



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I# the router ha) not in)talle& the BGP route) 4ou e"e!t7 4outhe sho3 ip bgp!o$$an& to veri#4 that BGP ha) learne& th

RTA#sho ip bgp

BGP table version is 3, local router ID is 1!"!"!"

tatus co$es% s su&&resse$, $ $a'&e$, istor, * vali$, + best, i

rigin co$es% i - IGP, e - GP, . - inco'&lete

/et0or /e2t o& 4etric 5ocPrf 6eigt Pat

* i1!!! 17"!189!1!8 1 " :

*+i1!1!1!1;3" 1!1!1!1 1 i

*+i1


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Loo avoi&an!e rule . that any route received from

neighbor must not be advertised to any other iBGPneighbor. iBGP reuire all router running iBGP )houl& %e !on

logi!al #ull $e)h toolog4 to allow routing in#or$atroagation through out the networ(2

Full $e)h J not )!ala%le )olution #or large networ(Two )olution) .

BGP Con#e&eration)

Route ReKe!tor

Route Re;ector


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RFC ,+;6

Route ReKe!tor) Rela"e& iBGP loo0revention rule)

Allowe& to rea&verti)e in !ertain !a)e)

Sea(er !la))i@!ation Route ReKe!tor /RR3

Route ReKe!tor !lient /!lient3 Regular iBGP )ea(er /non0!lient3

Route Re;ector


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A route reKe!tor i) BGP router that i) allowe& to %rea( the iBGP loo avoi&Route reKe!tor) !an a&verti)e u&ate) re!eive& #ro$ an iBGP eer to anoteer un&er )e!i@! !on&ition)2

B4 %rea(ing the rule)7 route reKe!tor) are u)e& to eli$inate the #ull $e)h an& allow #or %uil&ing iBGP networ() that )!ale ea)il4 an& !leanl42

Route Re;ector


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RR learn) re@" #ro$ .

eBGP eer. A&verti)e to all !lient) an&

non0!lient)

non0!lient.

ReKe!t to all !lient) !lient.

ReKe!t to all other !lient)an& to non0!lient)

Route Re;ector

materi ccnp routing (bgp')

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