BGP multihoming issues

remerolle

Lets say I have an HQ router which connects to 2 different ISPs. I want to dual-home with special circumstances in mind.

Lets say I only want to use my ISP2 in order to connect to one specific network maybe a corporate partner's network (9.9.9.0 /24 for example). But if my connection to ISP1 were to go down, I want to know allow any internet destined traffic out to ISP2.

I want the rest of my internet bound traffic to go to ISP1.

I want my BGP AS to me a non transit, but I do want to allow any traffic destined for our corporate partner's network the ability to traverse through my network from ISP2 to ISP1.

I am just getting in to these more advanced aspects of BGP, and I really would love some pointers in how to proceed. This is not for an actual company it is a personal lab of mine. Any help would be appreciated! Thanks for your time!

joshgibson82

There are really multiple ways to have that set up. You could use route maps, BGP tweeking, a mixture of static routes and BGP routes. How are the routes coming into your AS from each ISP? Do you get all internet routes or a default route or what?

That sounds interesting.

remerolle

In this hypothetical case I would get all routes from each ISP.

One thought I had was to not advertise any routes to HQ, except for the company partner's network. Then I could create 2 default routes. Since HQ only has the route to the partner's network it would only allow traffic to that network through HQ. I would of course throw up some ACLs to further secure the HQ. But this just seems like too much of a CCNA level work around. I want to utilize something more BSCI specific.