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Beginner

BGP Multi-homed local preference issue

Hi fellow cisco'ers or cisco'ites , I was wondering if you could help me with a little predicament im in.

I have an issue, i am required to create the topology shown below:

Picture1.png

I have deployed BGP in the most efficient way I could, this involved using static routes to connect the routers to each other and then set bgp to for neighbor ships using loopback addresses on each router, I have managed to get this working effectively thanks to multihop and what not.  I am now trying to make one of the two connections prefered over the other. I am finding this difficult as there is only one bgp relationship between these two routers meaning I cannot apply bgp attributes in the usual way (neighbor IP-ADDRESS route-map LOCAL-PREF in ) as it would apply to both connections instead of one. Any advice on how to implement preference in this situation would be helpful, Thanks for your time

Router Configs:

R1(config)# router bgp 65102

R1(config-router)# neighbor 172.16.1.1 remote-as 65101

R1(config-router)# neighbor 172.16.1.1 update-source loopback0

R1(config-router)# neighbor 172.16.1.1 ebgp-multihop 2

R1(config)# ip route 172.16.1.1 255.255.255.255 192.168.1.18

R1(config)# ip route 172.16.1.1 255.255.255.255 192.168.1.34

R2(config)# router bgp 65101

R2(config-router)# neighbor 172.17.1.1 remote-as 65102

R2(config-router)# neighbor 172.17.1.1 update-source loopback0

R2(config-router)# neighbor 172.17.1.1 ebgp-multihop 2

R2(config)# ip route 172.17.1.1 255.255.255.255 192.168.1.17

R2(config)# ip route 172.17.1.1 255.255.255.255 192.168.1.33

1 ACCEPTED SOLUTION

Accepted Solutions
Frequent Contributor

Re: BGP Multi-homed local preference issue

The underlying protocol you are using is static for the two links, so I don't think you will be able to prefer one link over the other using BGP attributes.

Alternatively, you can have two adjacencies and then apply BGP attributes. In fact, in that case, you won't have to tweak anything. By default BGP would prefer one over the other.

I also made a correction to my post as I mistook your multihop to maximum-paths. With static routes, multihop 2 is required.

HTH.

5 REPLIES 5
Frequent Contributor

Re: BGP Multi-homed local preference issue

How about:

R1(config)# ip route 172.16.1.1 255.255.255.255 192.168.1.34 200

R2(config)# ip route 172.17.1.1 255.255.255.255 192.168.1.33  200

Thanks.

Beginner

BGP Multi-homed local preference issue

I might be being silly but, I dont see how that would enable me to apply bgp attributes to the connections, could you elaborate? 

Frequent Contributor

Re: BGP Multi-homed local preference issue

The underlying protocol you are using is static for the two links, so I don't think you will be able to prefer one link over the other using BGP attributes.

Alternatively, you can have two adjacencies and then apply BGP attributes. In fact, in that case, you won't have to tweak anything. By default BGP would prefer one over the other.

I also made a correction to my post as I mistook your multihop to maximum-paths. With static routes, multihop 2 is required.

HTH.

Beginner

BGP Multi-homed local preference issue

Yeah good point that's is a choice, I am trying to avoid setting up two adjacencies as it will double the number of updates being sent between the neighbors, but its looking like the only option unless anyone's got any other ideas ?..

Beginner

BGP Multi-homed local preference issue

Cant find another way to solve this, looks like its going to have to be two adjacencies, Thanks for the help Rais

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