LDP is one of the core MPLS protocols. It was orginally designed
to establish point-to-point and multipoint-to-point LSPs that
reflected the topology as understood by the IGP routing protocol.
LDP has since been extended for several different uses.
When LDP is used as the control protocol for constructing
Point-to-Multipoint and Multipoint-to-Multipoint Label Switched
Paths ("MP LSPs") it contains a field that identifies the address
of a "root node". Intermediate nodes are expected to be able to
look up that address in their routing tables. However, if the route
to the root node is a BGP route, and if the intermediate nodes
are part of a BGP-free core, this lookup will fail.
This document specifies procedures which enable a MP LSP to be
constructed through a BGP-free core. In these procedures, the root
node address is temporarily replaced by an address that is known
to the intermediate nodes and is on the path to the true root node.
Working Group Summary
The document has been well reviewed by the MPLS working group.
There were no issues arrising.
There is one known implementation of this specification, and
a number of other vendors have indicated their intention to
Loa Andersson (firstname.lastname@example.org) is the Document Shepherd.
Adrian Farrel (email@example.com) is the Responsible AD.