Thanks a lot for the answers about IGP (and for the excellent book recommendation). The results so far are: 50% OSPF 37,5% IS-IS 12,5% IBGP (Using any IGPs when multipath occurs) 0% EIGRP The impressions are that the old backbones use IS-IS and the new ones are using OSPF. -- Marcelo Manta SAGA PGP fingerprint = E3 B8 AC AF 24 61 E7 E5 B8 38 01 D1 3C F4 32 5E