i have a simple topology like following :



using that topology i would like to learn about BGP routing protocol, i have configured all routers using BGP routing protocol, and everything fine until i check the routing table on R7, which theres no route to go to R1, as below :

R7
10.0.0.0/30 is subnetted, 3 subnets
C 10.4.4.0 is directly connected, Serial1/0
B 10.3.3.0 [200/0] via 10.4.4.1, 00:56:49
B 10.2.2.0 [200/0] via 10.4.4.1, 00:56:49

my first thought its because the neighbor of R7, the R3 doesnt get routing to the R1, but when i check it, it have, and can ping to R1 from R3

R3
10.0.0.0/30 is subnetted, 4 subnets
C 10.4.4.0 is directly connected, Serial1/1
C 10.3.3.0 is directly connected, Serial1/0
C 10.2.2.0 is directly connected, Serial1/2
B 10.1.1.0 [200/0] via 10.3.3.1, 01:09:05

any suggestion ??

BGP does not advertise a route to an iBGP peer if it learned that route from another iBGP peer

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www.mellowd.co.uk/ccie/

if it so, what should i do to make R3 advertise that route to R7, could i use default route ??

The easiest way is to make R2 peer with R7 as well. iBGP neighbours do not need to be directly connected.

The more complicated way is to make R3 a route reflector, or split the AS into confederations

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www.mellowd.co.uk/ccie/

i dont get it, should i put R7 and R2 in other AS that R3 ?? how about if i use "neighbor [ipaddress] ebgp-multihop [number of hops]" commands, would it work??

What? I never once said you need to use eBGP. So it makes no sense that R3 would be in a different AS or the ebgp multihop command. Don't just pull commands out of a hat and assume what will and won't work.

I said make R7 and R2 iBGP peers. R2 can peer with both R7 and R3 via iBGP

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www.mellowd.co.uk/ccie/

*grins sheepishly*

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Regards,

Steven King
San Diego Cisco User Group - http://www.sdcug.com
"The only time something is impossible is when you think it is." - Kevin Corbin, CCIE #11577

hi guys, i have tried to find the meaning and the way to making the R7 and R2 iBGP Peers, but i couldnt find the aswer till now, could u give me some simple explanation

thanks

Theres nothing to it really, set up a new neighbourship between the two devices...

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David
CCIE R&S #38338, CCIP, CCNP

http://networkbroadcast.co.uk - My Blog
http://twitter.com/davidrothera

i have added a neighbor command on both Router, but still the 10.1.1.0 route still not added into R7 routing table,

any suggestion about make a iBGP peers ?

You have added the neighbours but is the connectio between them actually up? Paste the output of 'show ip bgp summary'

_________________
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David
CCIE R&S #38338, CCIP, CCNP

http://networkbroadcast.co.uk - My Blog
http://twitter.com/davidrothera

heres the show ip bgp summary on R2

*Jul 24 15:42:32.962: %BGP-5-ADJCHANGE: neighbor 10.4.4.2 Up
R2(config-router)#do sh ip bgp summary
BGP router identifier 10.3.3.1, local AS number 1001
BGP table version is 5, main routing table version 5
4 network entries using 480 bytes of memory
5 path entries using 260 bytes of memory
3/2 BGP path/bestpath attribute entries using 372 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
Bitfield cache entries: current 2 (at peak 2) using 64 bytes of memory
BGP using 1176 total bytes of memory
BGP activity 4/0 prefixes, 5/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.1.1.1 4 1000 129 133 5 0 0 02:06:01 0
10.3.3.2 4 1001 133 131 5 0 0 02:06:12 3
10.4.4.2 4 1001 4 5 5 0 0 00:00:10 0

and heres on R7

BGP router identifier 10.4.4.2, local AS number 1001
BGP table version is 167, main routing table version 167
4 network entries using 480 bytes of memory
5 path entries using 260 bytes of memory
2/1 BGP path/bestpath attribute entries using 248 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 988 total bytes of memory
BGP activity 5/1 prefixes, 7/2 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.3.3.1 4 1001 6 5 167 0 0 00:01:20 2
10.4.4.1 4 1001 135 132 167 0 0 02:09:13 3

Use code tags. And do a show ip bgp on all and paste here

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www.mellowd.co.uk/ccie/

R7


R2


R3

code tags...

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www.mellowd.co.uk/ccie/

what is code tags ??

Before you paste some Cisco output put [code ] and then after the output put [/code ] (remove the spaces though from my example)

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David
CCIE R&S #38338, CCIP, CCNP

http://networkbroadcast.co.uk - My Blog
http://twitter.com/davidrothera

so what is causing the rib failure on R7 for network 10.4.4.0/30 ?

post
show ip bgp rib-failure
on R7

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"If you're good at anticipating the human mind. It leaves nothing to chance."
-Jigsaw

My guess would be the rib-failure is from the 4.2.2.0 subnet being a locally connected subnet on R7. The connected route has a better AD than the BGP route so it shows as a rib-failure in BGP.

Have you double checked that R7 is reachable from R1? Is there a route present in the routing table for that specific subnet?

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http://blog.movingonesandzeros.net/

R2 and R7 will need routes between them to become iBGP peers, are you running an IGP in AS 1001?

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"Where I excel is ridiculous, sickening, work ethic. You know, while the other guy’s sleeping? I’m working. While the other guy’s eatin’? I’m working. While the other guy’s making love, I mean, I’m making love, too. But I’m working really hard at it."