Re: IGPs in use

However, I know of three large networks in Europe that do use BGP as their sole IGP and I know of one other that is considering ditching OSPF and moving to BGP (they have bandwidth coming our of their ears so don't care about the granularity cost-metric gives you) because the CPU overhead of OSPF was too large for their network. Plenty of bandwidth but tight purse strings when it comes to hardware.

If BGP rides on TCP, how are the TCP sessions built if BGP itself is used as the IGP? How does this affect the hierarchy of the network since all iBGP speakers must be fully meshed?