
50
Figure 22 Establish an LDP LSP across the network core layer
To simplify the configuration, when setting up an LDP LSP across the core layer, you can use the
MPLS TE tunnel that is already established in the core layer. As shown in
, when using the
MPLS TE tunnel to establish the LDP LSP, you do not need to establish local LDP sessions between
neighboring LSRs in the core layer. All you need to do is to establish a remote session between the
ingress node and egress node of the MPLS TE tunnel. Then, label bindings can be exchanged and
an LDP LSP can be established between the MPLS TE tunnel ingress and egress. The LDP LSP is
carried on the MPLS TE tunnel. In this way, a hierarchical LSP is formed.
Figure 23 Configure an LDP LSP over an MPLS TE LSP
By default, LDP does not advertise any prefix-based label mapping message through a remote
session. To enable LDP to advertise prefix-based labels through a remote session, configure the
prefix-label advertise
command. For a description of the
prefix-label advertise
command, see
MPLS Command Reference
.
Protocols and standards
•
RFC 2702,
Requirements for Traffic Engineering Over MPLS
•
RFC 3212,
Constraint-Based LSP Setup using LDP
•
RFC 2205,
Resource ReSerVation Protocol
•
RFC 3209,
RSVP-TE: Extensions to RSVP for LSP Tunnels
•
RFC 2961,
RSVP Refresh Overhead Reduction Extensions