LDP Message
Discovery Message:
hello packet is sent to UDP port 646 to all-router multicast group (224.0.0.2)
Session Message:
It’s used to maintained, established, and terminated the session.
It’s using TCP port 646. Normally, it’s sent from loopback interface to loopback interface of peer.
Advertisement Message:
it’s used to create, change, and delete the table mapping for FEC (forwarding equivalent classes).
Notification Message:
it provide advisory information and signal error information
