Flooding Unknown Packets Across Mesh Groups
Broadcast, multicast, and unicast packets of unknown origin received from a PE router
are flooded to all local CE routers. They are also flooded to all of the PE routers in the
VPLS routing instance except the PE routers that are a part of the originating PE router
mesh group.
For example, if a multicast packet is received by the border router in Figure 64 on page 1280,
it is flooded to the two local CE routers. It is also flooded to routers PE1 and PE2 in the
LDP-1 mesh group and to routers PE3, PE4, and PE5 in the LDP-2 mesh group. However,
the packet is not flooded to routers PE6, PE7, and PE8 in the BGP mesh group.
Unicast Packet Forwarding
The PE border router is made aware of the composition of each PE router mesh group.
From the data plane, each PE router mesh group is viewed as a virtual pseudowire LAN.
The border router is configured to interconnect all of the PE router mesh groups belonging
to a single VPLS routing instance. To interconnect the mesh groups, a common MAC
table is created on the border router.
Unicast packets originating within a mesh group are dropped if the destination is another
PE router within the same mesh group. However, if the destination MAC address of the
unicast packet is a PE router located in a different mesh group, the packet is forwarded
to that PE router.
PE Router Mesh Groups for VPLS Routing Instances
A PE router mesh group consists of a set of routers participating in a VPLS routing instance
that share the same signaling protocol, either BGP or LDP. Each VPLS routing instance
can have just one BGP mesh group. However, you can configure multiple LDP mesh
groups for each routing instance.
The Junos OS can support up to 16 mesh groups on MX Series routers and up to 128 on
M Series and T Series routers. However, two mesh groups are created by default, one for
the CE routers and one for the PE routers. Therefore, the maximum number of user-defined
mesh groups is 14 for MX Series routers and 126 for M Series and T Series routers.
NOTE: In the VPLS documentation, the word router in terms such as PE router
is used to refer to any device that provides routing functions.
The Junos OS supports both forwarding equivalency class (FEC) 128 and FEC 129. FEC
129 uses VPLS autodiscovery to convey endpoint information. FEC 128 requires manually
configured pseudowires.
1281Copyright © 2017, Juniper Networks, Inc.
Chapter 35: Configuring Virtual Private LAN Service
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