BGP config on two different ISP

[izelakhe25]

Hello, can any one assist me on how to deploy BGP on a network with two different ISP. ISP A has a client router on the network and ISP B serve as backup with a client router on the same network, which made router A and B. The client wanted a situation when ISP A goes down ISP B can substitute automatically to avoid down time.

[JohnTylerPearce · Accepted solution]

I would setup IP SLA tracking for this. You can configure this on the core router, and have it ping the next hop

ip address of the primary ISP. If that link goes down, or doesn't respond it will automatically switch over in less

than a second.

[jesse.pratt]

Hi there,

Quick question, are you advertising an ip range that you own or is there two internet links in your office from two different carriers with their IP addressing?

If we are talking about two seperate ISP routers with their own different IP's from the ISP (not you advertising your own addresses) then what John suggested is your best bet. Setup two default routes one with a higher cost and apply a track object to the primary.

If you have your own blcok of IP's that you wish to advertise to two different ISP's there are a few ways to accomplish this.

1) Conditional advertisements (my personal favorite)

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080094309.shtml

2) You can use community statements and work with the ISP's to ensure correct return routing

3) AS prepending

If you require further information just say.

Thanks

Jesse