Configuring Vpls Multihoming (Fec 128) - Juniper EX9200 Features Manual

VPLS Feature Guide for EX9200 Switches

Configuring VPLS Multihoming (FEC 128)

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routers in the VPLS network. When the remote customer site is also multihomed, the
designated VE device triggers the creation of pseudowires to and from only the
designated VE device for the remote site.
The PE router originated one of the multihomed advertisements but did not select its
own advertisement as the best path.
This PE router is one of the redundant PE routers for the multihomed site; it was not
selected as the designated VE device. However, if this PE router has just transitioned
from being the designated VE device (meaning it was receiving traffic from the remote
PE routers addressed to the mulithomed customer site), the PE router tears down all
the pseudowires that it had to and from the other PE routers in the VPLS network.
The PE router receives the multihomed advertisements and selects a best path; it does
not originate any of these advertisements because it is not connected to the multihomed
customer site.
If the preferred path to the customer site (the designated VE device) has not changed,
nothing happens. If the preferred path has changed, this PE router brings up pseudowires
to and from the newly designated VE device and tears down the pseudowires to and
from the previously designated VE device.
If this PE router does not select a best path after running the BGP and VPLS path
selection process, the local PE router does not consider the remote site to exist.
When a VE device receives an advertisement for a Layer 2 NLRI which matches its own
site ID but the site is not multihomed, the pseudowire between it and the transmitting
PE router transitions to a site collision state and is not considered to be up.
VPLS multihoming allows you to connect a customer site to multiple PE routers to provide
redundant connectivity while preventing the formation of Layer 2 loops in the service
provider's network. A VPLS site multihomed to two or more PE routers provides redundant
connectivity in the event of a PE router-to-CE device link failure or the failure of a PE
router. For more information about VPLS multihoming, see
on page 61.
NOTE: If you want to enable multihoming for a VPLS routing instance, you
cannot also enable LDP signaling. You can only enable BGP signaling.
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 following sections describe how to configure VPLS multihoming. Some information
is also provided on single-homed site configuration versus multihomed site configuration.
VPLS Multihomed Site Configuration on page 67
VPLS Single-Homed Site Configuration on page 68
"VPLS Multihoming Overview"
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