MPLS VPN question

[nileshrathi]

                                           

Hi.. I am having some problems with VPNv4 RR.

R2 and R6 fa0/0 are configured as vrf interfaces. I have configured R5 as a VPNv4 neighbor for R2 and R6. All the routers within the elongated circle run MPLS

From my test configs what I see is that if I just configure (R2 as VPNv4 RR client of R5) and (R6 is not configured as a VPNv4 RR client of R5), R1 and R7 are still receiving subnets from each other. I was of the view that both R2 and R6 need to be VPNv4 clients of R5 for subnets to be advertised between R2 and R6 but thats not the case. Could somebody please advise why do we not need both(R2 and R6) to be RR clients of R5 ?

Regards

[Harold Ritter · Accepted solution]

Hi Nilesh,

This behavior is in line with RFC4456, section 6, which states:

1) A route from a Non-Client IBGP peer:

   Reflect to all the Clients.

2) A route from a Client peer:

   Reflect to all the Non-Client peers and also to the Client
   peers.  (Hence the Client peers are not required to be fully
   meshed.)

Regards

http://tools.ietf.org/html/rfc4456

[nileshrathi]

Hi Harold,

Apologies for the late reply. The RFC link was perfect. Dunno why I didn't google for it

Regards,

Nilesh