An ISP has an MPLS LDP core with redundant paths. The core is BGP-free and core routers do
not participate in BGP protocol. Several Internet customers reported that they are not able to
reach some Internet sites any more. The set of sites reported as having reachability issues
depends on the location of the customer. What is the most likely root-cause for this problem?
A.
Either a core link or an OSPF adjacency on a core link is down.
B.
An MPLS LDP session between a pair of routers in the core is down.
C.
An IBGP session between a pair of PE routers is down.
D.
Some EBGP sessions to some peers are down.
E.
Some core links are heavily congested.
F.
A denial of service attack is in progress.