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Strange BGP issue - not advertising BGP route

vincent-n
Level 3
Level 3

Hi all

I have a strange BGP advertising problem and was hoping that someone might be able to give me an answer.

I run BGP on a Catalyst 3750 switch running Enh Image ver 12.2(25r)SE1. On this switch I've configured BGP v4 on it. A router at a remote office is advertising the following subnets: 10.109.3.0/24; 10.109.5.0/24; 10.109.10.0/24; 10.109.100.0/24 and 10.109.200.0/24 to this Cat3750 switch. It's able to receive all 5 subnets just fine but for some reason, it'll only advertise on the first 4 subnets and not the 5th one on 10.109.200.0/24. I checked the switch and this is what it shows:

#sho ip bgp 10.109.3.0

BGP routing table entry for 10.109.3.0/24, version 1627

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to update-groups:

2

64900 64900

192.168.157.1 from 192.168.157.1 (10.198.78.36)

Origin IGP, localpref 100, weight 100, valid, external, best

Extended Community: RT:17477:78

#sho ip bgp 10.109.200.0

BGP routing table entry for 10.109.200.0/24, version 1496

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Not advertised to any peer

64900 64900

192.168.157.1 from 192.168.157.1 (10.198.78.36)

Origin IGP, localpref 100, weight 100, valid, external, best

Extended Community: RT:17477:78

The statement "Not advertised to any peer" is clearly the reason for it to not advertise the subnet on to other iBGP peers. I've checked out the link http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800945ff.shtml but it doesn't fix my problem.

Attached is a cut down version of my config and also other show ip bgp xxx commands. Thanks in advance fro your help.

1 Accepted Solution

Accepted Solutions

Harold Ritter
Cisco Employee
Cisco Employee

Vincent,

I would try using an outbound route-map instead of a distribute-list and see if the problem goes away.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

View solution in original post

5 Replies 5

arunsing
Level 1
Level 1

Hi Vincent, There are a few bugs with the 12.2 IOS train that you are using related to BGP. Try clearing the bgp neighborship and see if that fixes the issue.

Harold Ritter
Cisco Employee
Cisco Employee

Vincent,

I would try using an outbound route-map instead of a distribute-list and see if the problem goes away.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Harold Ritter
Cisco Employee
Cisco Employee

Vincent,

I would try using an outbound route-map instead of a distribute-list and see if the problem goes away.

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Thank you very much for your post. Implementing a simple route map together with a BGP soft resync has now fixed the problem. The command I used is 'clear ip bgp 10.95.3.19 soft out' just in case someone else is interested.

arunsing
Level 1
Level 1

Yes I will agree. Infact using route-maps instead of distribute lists is a workaround.

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