IBGP network broadcast towards 2nd hop

Post Reply
mouthpiec
Member
Posts: 16
Joined: 27 Aug 2013 10:58

IBGP network broadcast towards 2nd hop

Post by mouthpiec » 12 Oct 2017 07:45

Hi,

I have 4 routers having the same AS between them (IBGP).
Routers A1 and A2 host subnet Network A, while B1 and B2 host subnet Network B.

It was noted that A1 receives routes for subnet B from B1 while A2 receives routes for subnet B from B2.
In case link A1-B1 fails, A1 will loose all routes towards subnet B. Is there a way to receive these routes through A2?

Image

thanks in advance
sandro

silvio
Alcatel Unleashed Certified Guru
Alcatel Unleashed Certified Guru
Posts: 980
Joined: 01 Jul 2008 10:51
Location: Germany

Re: IBGP network broadcast towards 2nd hop

Post by silvio » 13 Oct 2017 02:00

If I remember correctly in iBGP (all BGP router in same AS) this is a normal behavior. Every route will be forwarded only one hop to avoid route loopings. You need a full-mesh (connection also between a1-b2 and b1-a2) or you has to configure route reflection.
regards
Silvio

mouthpiec
Member
Posts: 16
Joined: 27 Aug 2013 10:58

Re: IBGP network broadcast towards 2nd hop

Post by mouthpiec » 13 Oct 2017 02:32

thanks @Silvio.
That is what I thought too.
It is a problem from our end to connect the As with Bs since these are located on different cities.
By route reflection you mean the following:
-B2 sends routes to A2 which in turn reflects these routes to A1?
-B1 sends routes to A1 which in turn reflects these routes to A2?

and so on?

silvio
Alcatel Unleashed Certified Guru
Alcatel Unleashed Certified Guru
Posts: 980
Joined: 01 Jul 2008 10:51
Location: Germany

Re: IBGP network broadcast towards 2nd hop

Post by silvio » 15 Oct 2017 13:57

yes. But in this case every Router has to be route reflector for two RF clients. In my opinion this isn't the best way that all routers reflect the routes together. Normaly route reflector is used for external routes. And there is one central router that reflects the routes to the others and maybe one redundant router in a router cluster.
I think in your design a "normal" IGP like OSPF will be better...
regards
Silvio

Post Reply

Return to “OmniSwitch 6850 / 6850E”