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My question is simply whether or not BGP speakers can form peer relationships with other routers on the same broadcast domain in the following scenario.

I have two L3 switches running BGP, let's call them R1 and R2. They both host two of the same networks on (let's say) VLAN 10 and 20 using VRRP. I want to connect a new router each to R1 and R2. R3 connects physically to R1 on VLAN 10, and R4 to R2 on VLAN 20. In this scenario can R4 ever peer with R1, and similarly R3 with R2? Note they are all in the same AS.

If not, and I configure both R1 and R2 as route reflectors - is the appropriate configuration to have R1 serve as RR for R2 and R3, while also having R2 as RR for R1 and R4?

4

Yes, they can. Since they are all in the same AS, iBGP will peer across multiple hops. And as you are probably aware, you need all the BGP speakers in a full mesh.

  • Thanks very much. Though they don't necessarily need to be fully meshed if you're using route reflectors, right? – unclemeat Dec 6 '15 at 20:40
  • That's correct. – Ron Trunk Dec 7 '15 at 1:36

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