next-hop-self for update received from iBGP neighbor

[Tatiana]

Hi,

will next-hop-self still work for bgp update received from iBGP neighbor in ExtremeXOS?

for example for cisco additional routemap is required:

route-map RM-NHSset ip next-hop peer-address neighbor X.X.X.X route-map out RM-NHS While for juniper it works by default for iBGP neighbors within different clusters

[Henrique]

Just to clarify, here is a simple diagram and observations for both iBGP and eBGP scenarios:

eBGP scenario:

In the above scenario, router A will get the routes advertised by router "C" with the following information by default:

Destination: 200.200.200.0/24
Peer: 192.168.1.6
Next-Hop: 192.168.1.4 (router C)

If we enable next-hop-self in router "B" for BGP neighbor "A" we would get:

Destination: 200.200.200.0/24
Peer: 192.168.1.6
Next-Hop: 192.168.1.6 (router B)

iBGP scenario:

In the above scenario router B is the reflector for client/neighbor router "A".

Router "A" will get the routes reflected by router "B" (previously learned from router "C") with following information:

Destination: 200.200.200.0/24
Peer: 192.168.1.6
Next-Hop: 192.168.1.4 (router C)

This result will happen regardless of using "next-hop-self" option in router "B" to neighbor "A".

There is a route-policy option to include the "next-hop" action, but I don't believe that applies to this case.

[Stephane_Grosj1]

Changing the nh for eBGP is mandatory, you don't have to configure it. This parameter is for iBGP sessions which do not change nh by default. As Henrique said you'll need to specify it per familly address, without any it defaults to IPv4 unicast.

[Henrique]

Got the point. Thanks for the details.

I believe that will work only for routes learned from eBGP neighbors, otherwise it will keep the "C" router as next-hop address.

I will check if there is any route-policy to that and update this thread.

[Tatiana]

Thanks, I found that.

Let's say we have 3 Routers, A B and C.
A is route reflector client for B,
Between A and B, and B and C are iBGP sessions.
on the B router is configured #configure bgp neighbor "Cremoteaddr" next-hop-self

In case B will receive an iBGP update from A, will it send it to C with next-hop-self ? or this works only for BGP updates received from eBGP neighboors?