What will happen if iBGP link fails Enterprise level

[doncarei2]

The above diagram shows the setup of my network.

We have 2 site running service to provide content for our customer. Both ISP aggregate our ASN 4000 so that which client can find which ever AS path is closer to them.

Question is that if our iBGP link is down and both ISP continue to aggregate our ASN. Will our setup still works? because I feel that the network will be confuse now of which path to take

[John Blakley]

Your ibgp link is providing failover for when the respective ISP goes down. If the ibgp link goes down, it wouldn't affect the individual path for each site. (Site A can still get to ISP A and Web Server 1.) If you lose the circuit to ISP A *AND* the ibgp link, then all of your users would route to the Site B side. Also, if you lose any ISP circuit, A or B, the users will still go to the side that's up. Make sense? You can manipulate your paths in BGP to always select the ISP as the main path, and if that path goes down, then you could configure the ibgp neighbor as the next path to take.

HTH,

John

[doncarei2]

With update to the diagram with some IP range, so even without a ibgp link between site A and B, the best path will still be select to connect to my AS? So if without ibgp link and one site A is down, all route will go to site B still ?