Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 52)

28 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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MPLS Point-to-Multipoint Traffic Engineering
1
Though S2L sub-LSPs are signaled in separate Path and Resv messages, they are always part of
the same P2MP LSP. LSRs such as P2 in
Figure 12 , handle multiple incoming S2L sub-LSPs on the
same interface, allocates a single label and advertises it to LSR P1. It avoids unnecessary
duplication of traffic in the data plane.
S2L sub-LSP groups
S2L sub-LSPs can further be grouped into sub-groups using a node that is part of the P2MP LSP.
Such sub-groups should be signaled in a separate Path message or Resv message. In
Figure 12 ,
P2 groups S2L2 and S2L3 into a sub-group. Each sub-group is identified by the sub-group
originator ID (LSR P2) and the sub-group ID (assigned by LSR P2). Brocade devices support only
one S2L sub-LSP per Path or Resv message.
Grafting
The process of adding new egress LSRs to an existing P2MP LSP is known as grafting. Grafting can
be achieved using any one of the following methods:
• Implicit — Adding new S2L sub-LSPs to an existing Path message and refreshing the entire
Path message.
• Explicit — Adding egress LSRs by signaling only the impacted or the new S2L sub-LSPs in a new
Path message.
NOTE
Brocade devices support the explicit method of adding LSRs only and do not support the implicit
method.