PLANET XGS3-24042 - Manual (Page 671)

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 Second, use the “show ldp interface” command to check whether the LDP has been enabled
correctly on the interface after the connection succeeds. If the LDP has been correctly enabled but
cannot be displayed, it is possible that the interface is not in the UP mode or not configured with
interface label-switching.
 Then, make sure the adjacent interfaces are in the same segment, and check whether the LDP can
discover peers and establish adjacencies with them normally via the “show ldp adjacency”
command. If no peer is discovered or no adjacency is established, it is possible that the interfaces
may belong to different segments, or one of the local host and its remote neighbor disables multicast
HELLO. Besides, when establishing TCP connection, LSR ID is the default address, as, please
make sure advertise the LSR ID route to the remote end.
 Check whether the state of LDP session with “show ldp session” is operational, since only in this
state, LDP sessions can switch messages. If the LDP session can’t be established, use “show ldp”
to check the TCP addresses of the two parties, and lookup the route table to make sure the route of
the remote end is reachable.
 At last, given all above steps succeed, use “show ldp fec” to check the routes imported by LDP and
their information, or check the created entries with “show mpls ftn” and “show mpls ilm”.
 Besides, if there are configurations of LDP targeted peers, make sure that the remote end also
configures a LDP peer whose destination address is the host, or allows the receipt of HELLOs from
specified targets. The addresses specified by the two ends should be route-reachable.