Hello,
The easiest and fastest way to make a router choose one link over another is using the weight attribute. Since its the fist decision in the path selection. A couple things to note:
1. You can configure it per neighbor and even narrow it down to specific routes per neighbor as well.
2. Higher is better. If a router is learning a route the weight is 0 by default and if the route is locally originated the weight is 32768
3. Its a non-transitive attribute which means its locally significant and only affects the outbound traffic of the local router.
Command to implement:
router bpg 100
neighbor 1.1.1.1 weight 3000
This will give a weight of 3000 to all routes learned from the specified neighbor. You cna configure the neighbor with a route-map and in the route-map match on certain prefixes and set a weight there if you only want certain routes affected. You can do this on both routers. Or you cna use the next decision in the path selection of local preference.
This is like the weight attribute but it affects all iBGP neighbors and isnt shared with eBGP neighbors. Son on the router you want to use as your primary tou can configure a higher weight on one router and the other router (iBGP neighbor) should use that path for traffic.
rout-map LOCAL_PREF permit 10
set local preference 500
router bgp 100
neighbor 1.1.1.1 route-map LOCAL_PREF in
-David
