iBGP route reflector

[scottmanzie1]

Hi

In the following topology, what would be the best way to ensure the spokes prefer one HUB router for all routes over this iBGP route-reflector setup?

HUB router config

*************************************************
neighbor ELAN-IBGP-PEER peer-group
neighbor ELAN-IBGP-PEER remote-as 64700
neighbor ELAN-IBGP-PEER local-as 64700
neighbor ELAN-IBGP-PEER timers 10 30
neighbor ELAN-IBGP-PEER route-reflector-client
neighbor 192.168.201.1 remote-as 64700---> peer for other hub
neighbor 192.168.201.1 local-as 64700

neighbor 192.168.201.3 peer-group ELAN-IBGP-PEER
IDENTICAL LINES FOR ALL SPOKES

Spoke router config, identical on all spokes

******************************************************************
router bgp 64700
neighbor SPOKES peer-group
neighbor SPOKES remote-as 64700
neighbor SPOKES timers 10 30
neighbor SPOKES next-hop-self
neighbor 192.168.201.1 peer-group SPOKES
neighbor 192.168.201.2 peer-group SPOKES

Basic diagram attached

Thanks

[Giuseppe Larosa]

Hello @scottmanzie1 ,

by default the BGP route reflector server with the lowest BGP RID is preferred as this parameter is reported in the Cluster List attribute.

assuming that BGP RID = loopback address in your case all clients the SPOKES should prefer the routes reflected by 192.168.201.1 over the ones reflected by 192.168.201.2

So nothing has to be done to achieve the desired result.

Hope to help

Giuseppe

[scottmanzie1]

thanks for the reply Guiseppe. What I should have mentioned and failed to....

I am most interested in routes coming in from eBGP into the eLAN iBGP network

Both HUBs connected are connected to the same MPLS network. I want to ensure the spokes see the those MPLS routes via Hub 1.at the moment they do not.

I could possibly make amendments inbound on the routes coming from the MPLS neighbour, on the HUB routers. But I was wondering could I do anything on the ELAN iBGP only to force all subnets, from iBGP and eBGP sources via HUB 1

hopefully that makes sense

Thanks

[Giuseppe Larosa · Accepted solution]

Hello @scottmanzie1 ,

I understand however to be able to further troubleshoot

>>Both HUBs connected are connected to the same MPLS network. I want to ensure the spokes see the those MPLS routes via Hub 1.at the moment they do not.

Can you post a a

show ip bgp <MPLS-learned-prefix>

taken from a SPOKE client.

Be aware that the BGP advertisements will be treated as iBGP even if coming from eBGP sessions terminated on HUBS.

Before looking at the BGP Router-id or Cluster-List attribute the IGP metric to next-hop is looked if one of the HUB routers has a better metric is chosen even if its BGP router-id is higher.

If there are issues with IGP metric the best way to make the SPOKES to take the wanted decision is to set a local preference value attribute to a value higher then 100 (default value ) on the HUB that should be preferred.

router bgp 64700

neighbor <eBGP-MPLS-peer> local-preference 200

also to be considered

neighbor ELAN-IBGP-PEER next-hop self

this last statement on both HUB routers.

This should be enough to fix your issues.

Hope to help

Giuseppe