Vpls Multihoming Overview - Juniper ACX1000 Configuration Manual

VPLS Multihoming Overview

Copyright © 2017, Juniper Networks, Inc.
Many configuration procedures for VPLS are identical to the procedures for Layer 2 VPNs
and Layer 3 VPNs.
Virtual private LAN service (VPLS) multihoming enables you to connect a customer site
to two or more PE routers to provide redundant connectivity. A redundant PE router can
provide network service to the customer site as soon as a failure is detected. VPLS
multihoming helps to maintain VPLS service and traffic forwarding to and from the
multihomed site in the event of the following types of network failures:
PE router to CE device link failure
PE router failure
MPLS-reachability failure between the local PE router and a remote PE router
Figure 63: CE Device Multihomed to Two 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 63 on page 1237 illustrates how a CE device could be multihomed to two PE routers.
Device CE1 is multihomed to Routers PE1 and PE2. Device CE2 has two potential paths
to reach Device CE1, but only one path is active at any one time. If Router PE1 were the
designated VPLS edge (VE) device (also called a designated forwarder), BGP would
signal a pseudowire from Router PE3 to Router PE1. If a failure occurred over this path,
Router PE2 would be made the designated VE device, and BGP would re-signal the
pseudowire from Router PE3 to Router PE2.
Multihomed PE routers advertise network layer reachability information (NLRI) for the
multihomed site to the other PE routers in the VPLS network. The NLRI includes the site
ID for the multihomed PE routers. For all of the PE routers multihomed to the same CE
device, you need to configure the same site ID. The remote VPLS PE routers use the site
ID to determine where to forward traffic addressed to the customer site. To avoid route
collisions, the site ID shared by the multihomed PE routers must be different than the
site IDs configured on the remote PE routers in the VPLS network.
Chapter 35: Configuring Virtual Private LAN Service
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