Virtual Private LAN Services
7750 SR OS Services Guide Page 497
Figure 80: BGP Multi-Homing for VPLS
Figure 80 depicts the VPLS using BGP Multi-homing for the case of multi-homed CEs. Although
the picture depicts the case of a pseudowire infrastructure signaled with LDP for a LDP VPLS
using BGP-AD for discovery, the procedures are identical for BGP VPLS or for a mix of BGP and
LDP signaled pseudowires.
Information Model and Required Extensions to L2VPN NLRI
VPLS Multi-homing using BGP-MP expands on the BGP AD and BGP VPLS provisioning
model. The addressing for the Multi-homed site is still independent from the addressing for the
base VSI (VSI-ID or respectively VE-ID). Every multi-homed CE is represented in the VPLS
context through a site-id, which is the same on the local PEs. The site-id is unique within the scope
of a VPLS. It serves to differentiate between the multi-homed CEs connected to the same VPLS
Instance (VSI). For example, in Figure 81, CE5 will be assigned the same site-id on both PE1 and
PE4. For the same VPLS instance though, different SITE-IDs are assigned for multi-homed CE5
and CE6: for example, site id 5 is assigned for CE5 and site id 6 is assigned for CE6. The single-
homed CEs (CE1, 2, 3 and 4) do not require allocation of a multi-homed site-id. They are
associated with the addressing for the base VSI, either VSI-ID or VE-ID.
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