lately i'm starting to see networks as such that 2 sites with different BGP AS has backdoor connection between the sites. The preferred routes between the sites are via backdoor link.
The CE on both sites are doing BGP with ISP and IGP on the internal network, so both CE are advertising the same routes to ISP.
controlling routing in this scenario is quite a nightmare. Wouldn't it be better if both sites use the same AS?
so is there a pointer on how this should be done properly?