BGP SP Configuring a Transit AS problem

BGP SP Configuring a Transit AS problem 03.11.2012. u 12:45 · pre 170 meseci #1

U svrhu prirema za "CCIP BGP 642-661" radim jedan lab u GNS3, odakle i naziv teme...i naisao sam na jedan problem...evo topologije:

Par rutera u nekoliko razlicitih BGP AS-tema, na svakom ruteru objavljene mreze na interfejsima Lo1 i Lo2
Trenutno R2 nije peers sa R7, svi ostali izmedju sebe jesu + u AS 807 R6 je peers sa R7 R8 i R9 (kao sto crvene strelice pokazuju)
Sve je podeseno i radi kako treba sem jednog problema na ruteru R9...naime:
Kada pingam ruter R2 sa R9 ne moze! Ne samo ruter R2 nego bilo koji drugi...(ali sad cu se u primjeru vezati samo sa R2)
R9#ping 26.50.40.1 source 96.50.40.1

Citat:

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 26.50.40.1, timeout is 2 seconds:
Packet sent with a source address of 96.50.40.1
.....
Success rate is 0 percent (0/5)

Na R9 rute prema R2 su best i validne
R9#show ip bgp

Citat:

BGP table version is 13, local router ID is 96.50.50.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*>i26.50.40.0/24 6.6.6.6 0 100 0 654 133 205 500 i
*>i26.50.50.0/24 6.6.6.6 0 100 0 654 133 205 500 i
*>i46.50.40.0/24 6.6.6.6 0 100 0 654 133 i
*>i46.50.50.0/24 6.6.6.6 0 100 0 654 133 i
*>i56.50.40.0/24 6.6.6.6 0 100 0 654 i
*>i56.50.50.0/24 6.6.6.6 0 100 0 654 i
*>i66.50.40.0/24 6.6.6.6 0 100 0 i
*>i66.50.50.0/24 6.6.6.6 0 100 0 i
*>i91.191.57.0/24 6.6.6.6 0 100 0 654 133 205 i
*>i91.192.57.0/24 6.6.6.6 0 100 0 654 133 205 i
*> 96.50.40.0/24 0.0.0.0 0 32768 i
*> 96.50.50.0/24 0.0.0.0 0 32768 i

Nex hop adresa je dostupna i rute prema R2 se naravno nalaze u ruting tabeli
R9#ping 6.6.6.6

Citat:

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/92/132 ms

Na ruterima R7 i R8 radi sve bez problema, pa predpostavljam da je problem na relaciji izmedju R6 i R9...jer nisu direktno povezani
Neighbors izmedju njih je ok
R9#show ip bgp summary

Citat:

BGP router identifier 96.50.50.1, local AS number 807
BGP table version is 13, main routing table version 13
12 network entries using 1404 bytes of memory
12 path entries using 624 bytes of memory
7/6 BGP path/bestpath attribute entries using 868 bytes of memory
4 BGP AS-PATH entries using 96 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 2992 total bytes of memory
BGP activity 12/0 prefixes, 12/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
6.6.6.6 4 807 39 35 13 0 0 00:31:56 10

Sinhronizacija je iskljucena
R9#show run | s bgp

Citat:

router bgp 807
no synchronization
bgp log-neighbor-changes
network 96.50.40.0 mask 255.255.255.0
network 96.50.50.0 mask 255.255.255.0
neighbor 6.6.6.6 remote-as 807
neighbor 6.6.6.6 description peers_R6
neighbor 6.6.6.6 update-source Loopback0
no auto-summary

Stanje i na R6
R6#show run | s bgp

Citat:

router bgp 807
no synchronization
bgp log-neighbor-changes
network 66.50.40.0 mask 255.255.255.0
network 66.50.50.0 mask 255.255.255.0
neighbor 5.5.5.5 remote-as 654
neighbor 5.5.5.5 description peeers_R5
neighbor 5.5.5.5 ebgp-multihop 2
neighbor 5.5.5.5 update-source Loopback0
neighbor 7.7.7.7 remote-as 807
neighbor 7.7.7.7 description peers_R7
neighbor 7.7.7.7 ebgp-multihop 5
neighbor 7.7.7.7 update-source Loopback0
neighbor 7.7.7.7 next-hop-self
neighbor 8.8.8.8 remote-as 807
neighbor 8.8.8.8 description peers_R8
neighbor 8.8.8.8 ebgp-multihop 5
neighbor 8.8.8.8 update-source Loopback0
neighbor 8.8.8.8 next-hop-self
neighbor 9.9.9.9 remote-as 807
neighbor 9.9.9.9 description peers_R9
neighbor 9.9.9.9 ebgp-multihop 5
neighbor 9.9.9.9 update-source Loopback0
neighbor 9.9.9.9 next-hop-self
no auto-summary

Ruter R2 vidi ispravno rute na R9
R2#show ip bgp

Citat:

BGP table version is 17, local router ID is 26.50.50.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*> 26.50.40.0/24 0.0.0.0 0 32768 i
*> 26.50.50.0/24 0.0.0.0 0 32768 i
*> 46.50.40.0/24 10.0.0.13 0 205 133 i
*> 46.50.50.0/24 10.0.0.13 0 205 133 i
*> 56.50.40.0/24 10.0.0.13 0 205 133 654 i
*> 56.50.50.0/24 10.0.0.13 0 205 133 654 i
*> 66.50.40.0/24 10.0.0.13 0 205 133 654 807 i
*> 66.50.50.0/24 10.0.0.13 0 205 133 654 807 i
*> 76.50.40.0/24 10.0.0.13 0 205 133 654 807 i
*> 76.50.50.0/24 10.0.0.13 0 205 133 654 807 i
*> 86.50.40.0/24 10.0.0.13 0 205 133 654 807 i
*> 86.50.50.0/24 10.0.0.13 0 205 133 654 807 i
*> 91.191.57.0/24 10.0.0.13 0 0 205 i
*> 91.192.57.0/24 10.0.0.13 0 0 205 i
*> 96.50.40.0/24 10.0.0.13 0 205 133 654 807 i
*> 96.50.50.0/24 10.0.0.13 0 205 133 654 807 i

Uradim traceroute sa R9
R9#traceroute 26.50.40.1 source 96.50.40.1

Citat:

Type escape sequence to abort.
Tracing the route to 26.50.40.1
1 * * *
2 * * *

Pinga sa R2 prema R9
R2#traceroute 96.50.40.1 source 26.50.40.1

Citat:

Type escape sequence to abort.
Tracing the route to 96.50.40.1

1 10.0.0.13 48 msec 148 msec 32 msec
2 10.0.0.9 192 msec 68 msec 76 msec
3 10.0.0.5 172 msec 100 msec 120 msec
4 10.0.0.1 180 msec 196 msec 116 msec
5 192.168.0.2 292 msec 212 msec 284 msec
6 192.168.0.2 !H * !H

Vidim da ruter R6 pravi problem! i na njemu:
R6#ping 96.50.40.1 source 66.50.40.1

Citat:

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 96.50.40.1, timeout is 2 seconds:
Packet sent with a source address of 66.50.40.1
U.U.U
Success rate is 0 percent (0/5)

R6#traceroute 96.50.40.1 source 66.50.40.1

Citat:

Type escape sequence to abort.
Tracing the route to 96.50.40.1

1 192.168.0.13 68 msec
192.168.0.2 100 msec
192.168.0.13 16 msec
2 192.168.0.2 !H
192.168.0.13 !H *

Pitanje? Sta je pogresno u setup-u ili samom dizajnu?

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Re: BGP SP Configuring a Transit AS problem 03.11.2012. u 13:41 · pre 170 meseci #2

Ne mogu da citam ceo tekst, na prvi pogled meni lici kao da R6 ne radi kao RR, pa R7 i R8 ne dobijaju BGP rute od R9.

Pozdrav,
Vedran

Re: BGP SP Configuring a Transit AS problem 03.11.2012. u 13:55 · pre 170 meseci #3

Citat:

Djaki: Ne mogu da citam ceo tekst, na prvi pogled meni lici kao da R6 ne radi kao RR, pa R7 i R8 ne dobijaju BGP rute od R9.
Pozdrav,
Vedran

Ruteri R8 i R7 mi uopste nisu bitnu, npr zamisli da oni uospte nisu peers-ovi ni sa cim, interesuje me samo R9...tj dali on moze preko R6 izaci do ostalih AS-ova bez da je R6 Route Reflectors?

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Re: BGP SP Configuring a Transit AS problem 03.11.2012. u 16:46 · pre 170 meseci #4

Pa kako ti nisu bitni kad saobracaj izmedju R6 i R9 ide preko njih, a ako R6 nije RR, onda oni nemaju rute do R9 i ne znaju gde da posalju pakete cija je destinacija R9 :).
Mozes da izbegnes RR tako sto ces napraviti full mesh iBGP peering R6-7-8-9, ali najstandardnije resenje bi bilo da je R6 RR.

Re: BGP SP Configuring a Transit AS problem 03.11.2012. u 17:15 · pre 170 meseci #5

Ok jasno mi je to, ali me buni sto u ovakvoj konfiguraciji R9 moze da ima best + valid rutu prema npr R2 i R2 isto prema R9?

R9#show ip bgp
Citat:
BGP table version is 13, local router ID is 96.50.50.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*>i26.50.40.0/24 6.6.6.6 0 100 0 654 133 205 500 i
*>i26.50.50.0/24 6.6.6.6 0 100 0 654 133 205 500 i
*>i46.50.40.0/24 6.6.6.6 0 100 0 654 133 i
*>i46.50.50.0/24 6.6.6.6 0 100 0 654 133 i
*>i56.50.40.0/24 6.6.6.6 0 100 0 654 i
*>i56.50.50.0/24 6.6.6.6 0 100 0 654 i
*>i66.50.40.0/24 6.6.6.6 0 100 0 i
*>i66.50.50.0/24 6.6.6.6 0 100 0 i
*>i91.191.57.0/24 6.6.6.6 0 100 0 654 133 205 i
*>i91.192.57.0/24 6.6.6.6 0 100 0 654 133 205 i
*> 96.50.40.0/24 0.0.0.0 0 32768 i
*> 96.50.50.0/24 0.0.0.0 0 32768 i

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Re: BGP SP Configuring a Transit AS problem 03.11.2012. u 17:23 · pre 170 meseci #6

Pa zato sto je taj deo korektno iskonfigurisan. Proveri stanje na R7 i R8, probaj da stavis RR na R6 pa javi da li ti radi...

Re: BGP SP Configuring a Transit AS problem 04.11.2012. u 09:25 · pre 170 meseci #7

R9#traceroute 26.50.40.1 source 96.50.40.1 ti ne radi zato sto R7/R8 ne zna kako da dodje do 96.50.40.1

R2#traceroute 96.50.40.1 source 26.50.40.1 ti radi zato sto ce icmp reply doci od 192.
168.0.6 ili .9 u zavisnosti kuda paketi idu i oba rutera su direktno konektovana sa R9.

Cak i ovde vidis da ti R7/R8 kaze da ne moze da rutira pakete prema 96.50.40.1 zato sto ne zna kao da dodje do te mreze.

R6#ping 96.50.40.1 source 66.50.40.1 ti vraca ICMP unreachable messages

Recimo ako stavis da ti je R6 route reflector i R9 ti je route reflector client onda ce R7 i R8 znati kako da dodju do R6 loopbacks ali ces imati suboptimal routing :)

Potpis

Sto mozes danas ne ostavljaj za sutra!

Re: BGP SP Configuring a Transit AS problem 04.11.2012. u 17:57 · pre 170 meseci #8

@sale83 @Djaki
Hvala na odgovorima, razumio sam, probao sam i sa RR i sa full mesh... radi sve oke :D
sale83 sta bi trebalo tacno da znaci suboptimal routing :)

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Re: BGP SP Configuring a Transit AS problem 04.11.2012. u 22:22 · pre 170 meseci #9

Pa zbog next-hop-self na R6 za R7 i R8 paketi sa R7/R8 ce ice preko
R6 umesto preko direktno konektovanog linka. Ako pingujes R9 loopback
sa R7 paketi ce ici R7 - R6 - R9 umesto R7-R9.

Potpis

Sto mozes danas ne ostavljaj za sutra!

Re: BGP SP Configuring a Transit AS problem 04.11.2012. u 22:42 · pre 170 meseci #10

Citat:

sale83: Pa zbog next-hop-self na R6 za R7 i R8 paketi sa R7/R8 ce ice preko
R6 umesto preko direktno konektovanog linka. Ako pingujes R9 loopback
sa R7 paketi ce ici R7 - R6 - R9 umesto R7-R9.

Pa da, bas tako :) nisam obracao paznju na to...hvala :D

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