BGP: next-hop self Configuration Impact

Unanswered Question
Aug 2nd, 2008

Hello Experts,

I am working for an ISP. We have 2" VPN "RR" deployed in the Network.

All the Routers across the Network are having VPNv4 Session with both the RR's.

Few of the ASBR Routers do not contain "next-hop self" in their BGP session with VPN RR.

We are planning to deploy "next-hop self" command in the respective VPNv4 sessions:

Question:

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By adding the "next-hop self" command, i would like to know the exact Impact to my BGP Session.

Because both my VPN RR are feeding the VPNv4 Routes to all the Routers in the Network.

By adding the "next-hop self" will this impact my TRAFFIC or not.

Thanks in Advance for the Responses.

Best Regards,

Guru Prasad R

I have this problem too.
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Marwan ALshawi Sat, 08/02/2008 - 06:55

first of all

there will be no impact but there will be enhancemnt

in other words

lets say the RR connected to the ASBR and the ASBR connected through EBGP to other BGP AS

between the ASBR and the other BGP AS there will be a subnet

if u dont advertise this subnet either through ur IGP or within the IBGP through the network command u will loss connectivity with other AS

if appackt comes from EBGP and one of ur internal routers wants to answer or send back to it and if it dose not have the path or the network(BETWEEN THE ASBR AND OTHER AS ASBR) installed to the next hop of the packt

which is in this case the other AS ASBR( THE OTHER AS ASBR WILL BE THE NEXT HOP IN THE CASE) that why u need the subnet between ur ASBR and OTHER ASs installed on ur routing table.

BUT,when u add the next-hop-self

ur ASBR will change the next hop ip for any packt arrive from out side ur AS through that ASBR and **the ASBR will make him self the next hop for that route**

in this case u DO NOT need to advertise the network between ur ASBR and other ASs ASBR

thank you

Please, if helpful Rate

guruprasadr Sat, 08/02/2008 - 10:05

HI,

Thanks for your Response.

Have RATED your POST.

Best Regards,

Guru Prasad R

jaleelahmed.sd Sun, 08/03/2008 - 19:09

Hi, Configuring the Next-hop is a must in a clutered vpn rr formation.

if you dont configure next-hop means this will cause as no route over to the asbr.

and from asbr thr wount be any routes learnt.

thanks

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