Route Reflector Design

[jeffersoncbriones]

Dear Gurus,

I have some questions regarding RR design before i simulate it.

Diagram Informations

CORE-1 and CORE-2 - direct interface with GW routers (GW routers goes to ISP)

RR-1 and RR-2 - are for route reflector

ACC-1 and ACC-2 - are access gateway routers for clients

Questions

1. Since RR-1 will do ibgp only to GW-1 and GW-2 and RR-2 will do ibgp only to GW-3, GW-4 and GW-5, how will both RR's share bgp routes?

Is it ok to rrclient RR-2 to RR-1 and vice versa?

2. ACC-1 and ACC-2 are rrclient of RR-1 and RR-2, how will the path goes? will it still pass through RR-1 and RR-2. It should be ACC-1 going to CORE-1 and then GW.

For now i want to clear this things first. Hoping your support.

Thanks.
Jeff

[Reza Sharifi]

Jeff,

Since you have 2 different RRs, then you need to different RR clusters.  For example RR-1 can be cluster 1.1.1.1 and RR-2 can be cluster 2.2.2.2.

In order for these to work correctly, you will also need an IBGP connection between RR-1 and RR-2

HTH

Reza

[jeffersoncbriones]

Hi Reza,

Thanks for the info, so ibgp between the 2 RR's will do the sharing of routes? Or i will still configure each RR as client for each other?

Thanks.
Jeff

[Mahesh Gohil]

Hi Jeff,

There are two approch for RR design:

1- Putting both RR in same cluster:
    > Here you do not need to configure RR as a client. A normal full-mesh IBGP is required between
      two RR.
    > A route will be learned from a PE at both RR
    > One RR will ignore the route learned from other RR due to cluster-list attribute

2- Putting both RR in different cluster"
    > Even Here you do not client config because as per IBGP split-horizon rule route learned from client will be propogated to  all peers except the sender

Hope this helps

Regards
mahesh

[jeffersoncbriones]

Hi Mahesh,

For these topology there are no physical conection with both RR's. So you mean i would just enable ibgp on both RR and they will share routes? Coz both RR's learned internet routes via ibgp so it cannot be redistributed again via ibgp?

Thanks.
Jeff

[Mahesh Gohil]

Hi jeff,

Irrespective of physiclal topology you need full-mesh ibgp peering between RR's

Regards

Mahesh

[jeffersoncbriones]

Hi Mahesh,

already simulated it on gns3, to share the routes, i made both RR's as client also. is this ok? is there any problem in here just in case i run this on real scenario? Also, what pitfalls i should look at ?

Thanks.
Jeff

[Reza Sharifi]

Jeff,

Yes, the connection between the 2 route reflectors is just a normal IBGP session. There is nothing special about it.

HTH

Reza

[jeffersoncbriones]

Hi Reza,

Thanks for the reply, im just thinking of any routing loops that may cause problem. How bout the command " no bgp client-to-cliet-reflection",where is this use for?

Thanks a lot.

Jeff

[Reza Sharifi]

Hi Jeff,

You don't need no bgp client-to-client reflection.

This is used only when the local RR neighbors are fully meshed

have a look at this link for an example.

http://www.cisco.com/en/US/docs/ios/12_3t/ip_route/command/reference/ip2_b1gt.html#wp1076671

In your case, you just need a simple IBGP session between the 2 RRs and since each RR has a different cluster ID, routes will propagate from one RR to the other without being blackholed or ignored.

HTH

Reza