state machine is working fine. With debug ldp nsm a user can debug the events from NSM,
route add delete and entries to forwarding. With debug ldp advertise-labels a user
can debug access list issues. For detail information about the LDP packet send and receive
use debug ldp packet. For detailed analysis of the packet send and receive and to dump
the packet use debug ldp hexdump.
Packets not forwarding
Follow the below steps to troubleshoot the problem.
Procedure steps
1.
Ensure LDP adjacency is established session is UP show ldp adjacency
2. Ensure LDP session is UP
3. Check the session status show ldp session show ldp session <session
peer ip address>
4. Check the label binding and LDP lsp show ldp fec show ldp lsp
5. Check the forwarding table entry for LDP FTN show mpls table-forwarding
6. Check the routing table for the MPLS-LDP routes show ip route
7. Check the particular MPLS-LDP route is selected show ip route database
8. Make sure the forwarding entry and route database are in sync
9. Check the LDP LSP statistics for transmitted packets show mpls stats-lsp
10. Check the MPLS-LDP forwarding statistics for transmitted packets show mpls
stats-ftn
11. If the statistics are not getting updated, check the incoming data packet show
interface <interface name>
Isolating the cause and corrective action
•
Are label bindings advertise correctly? Isolate the problem by removing the policies.
• Is Forwarding at fault?
• Is Configuration correct in the peer routers, and in the entire LSP path? Execute the
command clear ldp adjacency <LDP adjacency address> in global mode to
clear a particular ldp adjacency. Make sure the session comes up after the traffic is flowing
correctly. Execute the command clear ldp adjacency all to clear all ldp adjacency.
Apart from the protocol the problem may be related to another system. Shut down and
restart the incoming and outgoing interfaces
Troubleshooting LDP LSP
Troubleshooting August 2013 117
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