I connect AREA 3 (router A) to AREA 0 ( router B) by the transit AREA 1. The router-id of the router A is its loopback, so is the router B. Should I treat the router A as a BACKBONE router? I apply the authentication in AREA 0, not in the route...

Normally, the Loopback is used for iBGP peers, not for eBGP peers, that connect directly. But with BGP confederation, how we use the update-source interface?

A router runs OSPF and ISIS. OSPF runs on s0 and s1, ISIS runs on s2 and s3. When redistribute each other, the address of s0 and s1 are imported into ISIS, but the address of s2 and s3 are not imported into OSPF. Why does this happen? I have to a...