Juniper JUNOSE 11.2.X BGP AND MPLS User Manual

within the network. You can use the traffic engineering (TE) capability of LSPs to achieve
consistent QoS control and efficient use of network resources, and create
point-to-multipoint LSPs to deliver data from one ingress LSR to multiple egress LSRs.
The flow of traffic in a point-to-multipoint LSP is not restricted to the paths that are
followed for multicast or shortest path routing; instead, you can explicitly configure the
values to determine the path. Packet replication takes place only when packets are
forwarded to two or more different destinations requiring different network paths.
A point-to-multipoint TE tunnel is composed of multiple point-to-multipoint LSPs. To
scale to a large number of nodes or branches in a point-to-multipoint LSP, each LSP is
uniquely identified by a point-to-multipoint ID, which is unique for the entire LSP,
regardless of the number of branches or leaves it contains. A point-to-multipoint LSP is
composed of multiple source-to-leaf sub-LSPs. These sub-LSPs are formed between
the ingress and egress LSRs to form the point-to-multipoint LSP.
Point-to-multipoint LSPs can be signaled using one or more path messages. If a path
message signals only one sub-LSP, it targets only one leaf in the point-to-multipoint
tunnel. Because a single path message might not be large enough to contain all the
sub-LSPs in the tunnel and also because you can create path messages specific to a
sub-LSP in the tunnel, you can use multiple path messages. However, if you want to
minimize the number of control messages required to configure a point-to-multipoint
tunnel, you need to use a single path message to signal multiple sub-LSPs.
The following are some of the benefits of using point-to-multipoint LSPs:
•
A point-to-multipoint LSP allows you to use MPLS TE for point-to-multipoint data
distribution. This functionality provides better control over the path chosen to transmit
traffic than that provided by IP multicast.
•
You can add and remove branch LSPs from a main point-to-multipoint LSP without
disrupting traffic. The unaffected parts of the point-to-multipoint LSP continue to
function normally.
•
You can enable link protection on a point-to-multipoint LSP. Link protection can provide
a bypass LSP for each of the branch LSPs that make up the point-to-multipoint LSP.
If any of the primary paths fail, traffic can be quickly switched to the bypass path.
•
You can configure branch LSPs statically, dynamically, or as a combination of static
and dynamic LSPs.
•
You can enable graceful restart on point-to-multipoint LSPs.
Using E Series Routers as Egress LSRs
You can use E Series routers as egress LSRs in a point-to-multipoint LSP. To create a
point-to-multipoint LSP and to use E Series routers as egress LSRs, no special
configuration is required. The configuration that you made for point-to-point LSPs, which
enables MPLS RSVP-TE on the interface that must signal an LSP in that virtual router
context, is sufficient.
Figure 61 on page 273 shows a point-to-multipoint LSP with multiple egress LSRs. The
multicast source sends a packet to the ingress router, LSR 1, which in turn sends the
packet on the point-to-multipoint LSP to the branch router, LSR 2. The branch router,
Copyright © 2010, Juniper Networks, Inc.272
JunosE 11.2.x BGP and MPLS Configuration Guide

Juniper JUNOSE 11.2.X BGP AND MPLS Specifications

General

Brand	Juniper
Model	JUNOSE 11.2.X BGP AND MPLS
Category	Software
Language	English