MPLS LDP

LDP is one of the protocols used in MPLS networks to establish label-switched paths (LSPs) and enable forwarding of labeled packets.

Here’s an overview of how MPLS LDP works:

• Neighbor Discovery and Session Establishment:
  • LDP routers use a multicast address, 224.0.0.2, for neighbor discovery. They send LDP Hello messages to this multicast address on UDP port 646. These Hellos help routers discover potential LDP neighbors on the same subnet.
  • Once a router receives a Hello message from a potential neighbor, it establishes a TCP session with that neighbor using TCP port 646. This session is crucial for reliable communication between LDP peers.
• Label Assignment:
  • In an MPLS network, routers assign a unique label to each IP prefix or Forwarding Equivalence Class (FEC) injected into the routing protocol such as Open Shortest Path First (OSPF) or IS-IS.
  • Each label represents a specific destination network. All packets destined for a particular IP subnet can be grouped...