iBGP and Floating Static Routes

[alistair777]

Hello,

Consider a typical multi-homing scenario with R1 and R2 connected to ISP1 and ISP2 respectively, with both sites receiving default routes learnt by their respective peers.

R1 and R2 are peered together with iBGP setup with 'next-hop-self' on the neighbor relationship.

If ISP1 was link was to go down, would a floating static route be required to redirect traffic to ISP2 via R2, or would this new default route be injected via iBGP into R1 from R2 once the BGP timers have expired?

Many Thanks,

Alistair

[Nagendra Kumar Nainar · Accepted solution]

Hi,

floating static is not required. In your example, R1 and R2 will receive default route from ISP via eBGP?. If yes, that is sufficient.

When link to ISP1 goes down, R1 will remove the route learnt from ISP1 and will use the iBGP learnt route from R2 and redirect any traffic to R2.

-Nagendra

[John Blakley · Accepted solution]

The newly learned route should be put into the table once your timers expire. If you have this setup, you should be able to see both default routes in your bgp table with one being the preferred. The other would be put into the table when your affected router withdraws the router.

HTH,

John