Flooding Unknown Packets Across Mesh Groups; Unicast Packet Forwarding; Bgp Route Reflectors For Vpls - Juniper EX9200 Features Manual

VPLS Feature Guide for EX9200 Switches

Flooding Unknown Packets Across Mesh Groups

Unicast Packet Forwarding

BGP Route Reflectors for VPLS

14
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
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.
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.
In large networks, it might be necessary to configure BGP route reflectors to reduce the
control plane workload for the routers participating in the VPLS network. BGP route
reflectors can help to reduce the workload of the network control plane in the following
ways.
Making it unnecessary to configure all of the VPLS PE routers in a full mesh.
Limiting the total volume of BGP VPLS messages exchanged within the network by
transmitting messages to interested routers only (instead of all of the BGP routers in
the network)
Reducing the network signaling load whenever another BGP router is added to or
removed from the network
The basic solution to these problems is to deploy a small group of BGP route reflectors
that are in a full mesh with one another. Each of the VPLS PE routers is configured to
have a BGP session with one or more of the route reflectors, making it unnecessary to
maintain a full mesh of BGP sessions between all of the PE 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.
Figure 2 on page
Copyright © 2016, Juniper Networks, Inc.
13,