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Silver

Adding RT

Say I have a PE-CE BGP across a VRF. If I change the RTs in the VRF (i add some and dont remove any) my BGP resets. Can anyone let me know why this should happen ? What is the BGP update message in such a scenario

3 REPLIES
Cisco Employee

Re: Adding RT

This is normal behavior. The BGP session is reset because of the VRF configuration change. The following message is also issued:

00:08:50: %BGP-5-ADJCHANGE: neighbor 192.168.12.1 vpn vrf red Down VRF config change.

No BGP message is sent the the peer. The TCP session is simply reset.

Let me know if I answered your question,

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
Silver

Re: Adding RT

Hi Harry,

I just wanted to know why this was normal. This creates a problem for us when we tweak with our Mgmt RTs for our customers as it brings the session down. What exactly is the relationship between the change in RTs and the BGP across the link.

Thanx a lot for the reply

Cisco Employee

Re: Adding RT

The BGP session reset is done so the prefixes learnt from the CEs are reprocessed to reflect the new route-target configuration.

Note that the hard session reset is only triggered when a "route-target export" is added or removed.

For a "route-target import" change, IOS sends a route-refresh request if this option has been negotiated with the neighbor, otherwise it also resets the session.

There is a DDTS opened to have the same behavior for a route-target import and export. It is CSCdp32976.

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
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