More about targeted LDP
adjacencies and LDP adjacency discovery
The establishment of pseudowires in LDP-signaled L2VPNs is accomplished
by PE devices through the use of the Label Distribution Protocol. LDP is
responsible for constructing, advertising, maintaining, and deleting label
bindings for pseudowires.
PE devices exchange Targeted Hello messages to locate and establish LDP
sessions, or adjacencies, with other PE devices. One such session, or
adjacency, is shown in
Targeted LDP adjacency.
Targeted LDP
adjacency

Peer LDP speakers on peer PEs establish a TCP-based communications
session with each other. Once the session is established, tunnel label data can
be exchanged to construct pseudowires.
The
MPLS Topology Server
discovers the LDP speakers and LDP sessions that are associated with
pseudowires. The
MPLS Topology Server
also discovers the LDP speakers and LDP sessions that are associated with LDP
LSPs, as described in
“More about LDP
adjacencies and LDP adjacency discovery” on page 67.