VPLS Features
Page 274 7210 SAS M Services Guide
Spoke SDP Based Redundant Access
This feature provides the ability to have a node deployed as MTUs (Multi-Tenant Unit Switches)
to be multi-homed for VPLS to multiple routers deployed as PEs without requiring the use of
mVPLS.
In the configuration example displayed in Figure 42, the MTUs have spoke SDPs to two PEs
devices. One is designated as the primary and one as the secondary spoke SDP. This is based on a
precedence value associated with each spoke. If the primary and secondary spoke-SDPs have the
same precedence value, the spoke-SDP with lower ID functions as the primary SDP.
The secondary spoke is in a blocking state (both on receive and transmit) as long as the primary
spoke is available. When the primary spoke becomes unavailable (due to link failure, PEs failure,
etc.), the MTU immediately switches traffic to the backup spoke and starts receiving/sending
traffic to/from the standby spoke. Optional revertive operation (with configurable switch-back
delay) is applicable only when one of the spokes is configured with precedence of primary. If not,
this action does not take place. Forced manual switchover is also supported.
To speed up the convergence time during a switchover, MAC flush is configured. The MTUs
generates a MAC flush message over the newly unblocked spoke when a spoke change occurs. As
a result, the PEs receiving the MAC flush will flush all MACs associated with the impacted VPLS
service instance and forward the MAC flush to the other PEs in the VPLS network if “propagate-
mac-flush” is enabled.
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