PBB Features
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There are a number of advantages to this approach. Firstly, the PBB-TLV presence indicates this is
a PBB MAC Flush. As a result, all PEs containing only the B-VPLS instance will automatically
propagate the LDP MAC withdraw in the B-VPLS context respecting the split-horizon and active
link topology. There is no flushing of the B-VPLS FIBs throughout the core PEs. Subsequently,
the receiving PBB VPLS PEs will use the BMAC and ISID list information to identify the specific
I-VPLS FIBs and the CMAC entries pointing to the source BMAC included in the PBB TLV.
An example of processing steps involved in PBB MAC Flush is depicted in Figure 113 for the case
when a Topology Change Notification (TCN) is received on PBB PE 2 from a QinQ access in the
I-VPLS domain.
Figure 113: TCN Triggered PBB Flush-ALl-but-mine Procedure
The received TCN may be related to one or more I-VPLS domains. This will generate a MAC
Flush in the local I-VPLS instance(s) and if configured, it will originate a PBB MAC flush-all-
but-mine throughout the related B-VPLS context(s) represented by the white circles 1-8 in our
example.
A PBB-TLV is added by PE2 to the regular LDP MAC flush-all-but-mine. BMAC2, the source
BMAC associated with B-VPLS on PE2 is carried inside the PBB TLV to indicate who “mine” is.
The ISID list identifying the I-VPLS affected by the TCN is also included if the number of
affected I-VPLS is 100 or less. No ISID list is included in the PBB-TLV if more than 100 ISIDs
are affected. If no ISID list is included, then the receiving PBB PE will flush all the local I-VPLS
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