BGP Multihomming - two links to the same ISP

[Amos Kafwembe]

hi guys,

I am trying to set up BGP multi-homming - two links to a single ISP. someone please point me in the right direction.

[Francesco Molino]

Hi,

What do you want to achieve with 2 links to the same ISP? Is it one path prefered over the other? Is it some kind load sharing?

What routing information are you receiving from your ISP?  Are you connected with 2 links on same ISP router or on 2 routers?

With more information, I would be able to help you. Otherwise, you have a nice document on Cisco site that can helps based on the design you have:

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html#anc10

Thanks

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[Amos Kafwembe]

Hi Francesco,

So, its one path preferred over the other. The two links are terminating on the same router on client side and terminating at two different points to the ISP (geographically separate locations for redundancy) 

[Francesco Molino]

Hi

Ok you want to use 1 link and the other only if the 1st one goes down.

You can announce your network with a as-path prepend on the second link and internally you can use local-pref for example to prefer one link over the other.

Does that make sense for you?

Thanks

PS: Please don't forget to rate and mark as correct answer if this answered your question

[Amos Kafwembe]

makes sense. I am just lab"ing it up and testing...

[Billm]

Hi Amos and Francesco,

Sorry to thread jack....

Amos, I was wondering if you completed this setup? I have the exact same scenario.

I haven't configured BGP in about 15 years and that was as a Test Engineer. :-)

I referenced the link above. Nice doc, but we are not using Load Balancing.

IPs and AS's are not correct.

I need a simple config.

We are Router A.

S1 will be a redundant link with a smaller pipe than S0.

We are not load balancing.

All we need from the ISP is the default route.

TIA!

[Francesco Molino]

Hi 

You're receiving a default route from your 2 ISP. To prioritize the traffic going to 1 isp and use the second add fallback, you can use bgp attributes like weight, local-pref on your router to make 1 link primary and the other secondary.

Does that helps?

Thanks 

PS: Please don't forget to rate and mark as correct answer if this answered your question