When you have multi-exits from your BGP segment, you don’t need default routes already, you needs specific routes from all of them. Closest route from AS-Path attrubute will be chosen as next-hop to one of three ISP. If you want to force the traffic flow from 3rd to first ISP, play with ATT like as-path, local preference and MED.
Hello.. I have a similar question and a problem I am facing for a while and have not received a proper solution.
We have 2 bgp peers.
Problem faced:
No pages load all of a sudden no pages load. If we shutdown one peer everything works great. The only solutions is to restart the router.
What it looks like from my perspective the outgoing traffic is unable to find a route between two peers until we restart and then everything works fine.
This largely depends on your BGP edge design and whether or not the peers are fully meshed inside your AS. If the routes learned from your upstreams are only present at the border routers then you’ll need aggregate routes injected form the border routers to draw traffic towards one of those peers.
An example. Apple Computers uses 17.0.0.0/8 , if you want traffic destined for Apple to traverse a specific upstream, then you can advertise a 17.0.0.0/8 summary into your network with a local preference assigned to the BGP border router you want it to go to.
Obviously you can’t do this for every BGP prefix, but identifying large IP blocks for webscale companies like Apple, Facebook, Google, YouTube, etc and advertising aggregates or leaking specific routes into the interior of your network can help to balance traffic across the different speed upstreams.
BGP Communities if they are available from your upstream can be used to help manage traffic inbound to your AS and achieve some load balancing. Check woth your provider to see what options you have to set local preference within your provider’s AS and prioritize or de-prioritize your prefix advertisements within the upstream provider’s AS.
Another option is to use software like Noction to help manage advertisements dynamically and detect packet loss and congestion. There is a free version that works with MikroTik.