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superkliko
Beginner

Updates and data flow on bgp route reflector

Hi,

In OSPF, designated router is used only for updates propagation. The data flow between Drothers is flowing directly between them without having to pass through DR.

I'm not sure how data between iBGP peers flow when we use router-reflectors.

I understand that traffic will be forwarded based on best route in routing table, which probably for BGP prefixes will be route-reflector as this router will add its IP as next-hop.

If traffic flows through route-reflector, isn't that causing huge traffic on RR ?

Please help to clarify this.

Thanks

1 ACCEPTED SOLUTION

Accepted Solutions
Vinit Jain
Cisco Employee

Hello,

The BGP RR may or may not be in the forwarding path. The traffic is forwarded based on your IGP path. The main job of RR is to reflect the routes from one IBGP to all the other IBGP peers which are route-reflector clients. The Next-hop is usually not changed with RR's unless you have a route-map to change the next-hop for the prefixes. Thus, the lookup for the BGP next-hop is done via the IGP and then down the FIB to forward the traffic. it totally depends on your design if RR will be in the forwarding path or not. Usually RRs are not in the forwarding path.

Hope this answers your question.

Regards

Vinit

Thanks
--Vinit

View solution in original post

2 REPLIES 2
Vinit Jain
Cisco Employee

Hello,

The BGP RR may or may not be in the forwarding path. The traffic is forwarded based on your IGP path. The main job of RR is to reflect the routes from one IBGP to all the other IBGP peers which are route-reflector clients. The Next-hop is usually not changed with RR's unless you have a route-map to change the next-hop for the prefixes. Thus, the lookup for the BGP next-hop is done via the IGP and then down the FIB to forward the traffic. it totally depends on your design if RR will be in the forwarding path or not. Usually RRs are not in the forwarding path.

Hope this answers your question.

Regards

Vinit

Thanks
--Vinit

View solution in original post

Thanks for reply Vinit.

 

Basically I missed that important detail. That detail gave the answer.

 

By default, RR is not changing any attribute or next-hop. So by default RR doesn't participate in forwarding path unless we change the next-hop to its self.

Regards 

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