I'm trying to turn on MPLS in my network. This network includes some number of Cisco 720x and 750x routers, connected with OSPF protocol.
I turn on the MPLS on all of them, but they don't see each other
(the command 'sh mpls ldp neighbor' don't show any neighbors, but 'sh mpls ldp discovery' shows them all).
After adding one new Cisco 7500 (without OSPF) it see one of
'old' routers as its neighbor, and vice versa. After I configure OSPF
on this new router, it losts its neighbor.
Are you using loopbacks for your Router ID, if so are you using a /32 mask (or the " ip ospf network point-to-point" command if not a /32 mask). If not MPLS will advertise the RID with the configured mask but OSPF will advertise it as a /32, this will cause a mismatch between MPLS and OSPF and cause label binding to fail.
Try the following URL's for hints on troubleshooting MPLS: