A network operations engineer of company ABC is responsible for the operations and
maintenance aspects of the MPLS backbone. The MPLS backbone is built by using MPLScapable routers that are connected with Gigabit Ethernet and POS interfaces. A complaint was
received about the lack of connectivity between two sites of the end customer of the ABC
company. This customer relies on the availability of the MPLS label-switched path that is provided
by the backbone network of company ABC. The operations engineer quickly determined that the
MPLS label entries for certain prefixes provided by LDP were missing on one of the provider edge
routers that connected to the customer router. The operations engineer also determined that the
LDP session of the PE router was down with some of its neighbors in the backbone.
Which three of the following statements represent valid considerations for further troubleshooting?
(Choose three.)
A.
A Layer 1 or 2 connectivity problem might be causing LDP to be unable to discover link-local
peers.
B.
The MPLS label-switched path ping to the LDP router ID of the peer will be helpful to determine
the issue with LDP.
C.
A ping that is using the PE’s own transport address as source might help to determine if the
LDP transport addresses of the peers are unreachable.
D.
Interface label space might be incorrectly configured, or the router might be unable to allocate
the interface label.
E.
There could be a password mismatch between the LDP neighbors. Logging messages might
uncover a message that is related to password mismatch.
F.
A fault or a misconfiguration on the backbone in the downstream direction might be causing
label retention problems.