topic BGP Multihoming with 2 ISP with 1 router each site in Routing

BGP Multihoming with 2 ISP with 1 router each site

frsisqo14344 — Mon, 04 Mar 2019 22:13:28 GMT

Hi how do you configure BGP in the below scenario?

R1/R2 = Customer Router

ISP1

ISP2

R1 connected to ISP1 and ISP2, R2 to ISP1 and ISP2, R1 connected to R2. So far most design and configuration I have seen is R1 to ISP1, R2 to ISP2, R1 to R2.

Thanks

BGP Multihoming with 2 ISP with 1 router each site

darren.g — Thu, 10 Nov 2011 00:33:02 GMT

frsisqo14344 wrote:

Hi how do you configure BGP in the below scenario?

R1/R2 = Customer Router

ISP1

ISP2

R1 connected to ISP1 and ISP2, R2 to ISP1 and ISP2, R1 connected to R2. So far most design and configuration I have seen is R1 to ISP1, R2 to ISP2, R1 to R2.

Thanks

How much redundancy do you want?

I implemented a similar situation, except I ran a layer two network with a couple of VLAN's between the two routers and VRRP on the ISP interface so that if one router failed the toher would take over and still maintain my BGP adjacency with both ISP's - I also ran an iBGP between the two routers, and had the link to the "inside" vias my firewall running VRRP as well.

If you don't need that kind of redundancy, then your way will work - just run iBGP between the two routers and let them sort out the best route between them.

Cheers.

BGP Multihoming with 2 ISP with 1 router each site

smitesh kharecha — Thu, 10 Nov 2011 06:54:28 GMT

Hi,

Best implementation for the redundancy level you want will be:

On LAN side Configure HSRP

Run iBGP between R1 and R2

and eBGP with ISP.

That if you want normal BGP behaviour. Means it will use any single ISP at the moment for the best routes.

If you want to load balance the things between your 2 ISP, then you need to tweak BGP.

HTH,

Smitesh