bgp multihomed to one isp.

JSW77

if i am running bgp between two routers (say my border router and the isp), and i have a t3 line and t1 line (for redundancy) going to the same isp, how would i configure my router to use the t3 line only until it goes down, then use the t1 line? can i use a floating static route and still be running bgp? if so, how would i go about this? i appreciate the help.

techman-aka-Format

hey jsw77, I just got done with my BGP case study. WHen you are multihoming two links to Isp using bgp, these are the commands you would use.

neighbor x.x.x.x remote-as 100
neighbor x.x.x.x route-map t3 out
neighbor x.x.x.x remote-as 100
neighbor x.x.x.x route-map t1 out

route-map t1 permit 10
set metric 150

route-map t3 permit 10
set metric 50

you have to configure route maps to the links. then you configure the bgp configs to the route-maps. plus the neighbor commands with the remote-as number to set up neighbor adjacencies.

ip route 0.0.0.0 0.0.0.0 Serial0/2
ip route 0.0.0.0 0.0.0.0 Serial0/3 220

then you put in the static routes, with the floating route . since BGP external uses and administrative distance of 200, i used 220. just use a number like that for the fallback route.
the metric statements determine which route will be the primary link for the ISP. the lower metric of 50 has the t3 link as the primary. but if that link goes down the t1 takes over as the primary until the t3 comes back up. this is how you do it. well that's about it. I hoped this helped you., techman