I have a network with three links (ISPA, 3MB, ISPB, 1.5MB, ISPC, 50MB). I have three different speeds, and as such, ISPs A and B are primarily used for redundancy. I'm currently receiving routes from all three providers, but filtering a number of them on the backup links. As I would look to route traffic out the larger pipe near exclusively, I feel as though I do not need to retrieve a full routing table from all the ISPs, and could merely synchronize default routes.
Is this the case? Is there a way to limit BGP to only synchronizing next-hop or local routes? I'm worried about enabling full synchronization, as I'm running with older routers, and I'm working with limited amounts of RAM.