Virtual Private LAN Services
7750 SR OS Services Guide Page 781
Optimization for Improved Convergence Time
Assuming that MMRP is used in a certain B-VPLS, under failure conditions the time it takes for
the B-VPLS forwarding to resume may depend on the data plane and control plane convergence
plus the time it takes for MMRP exchanges to settle down the flooding trees on a per ISID basis.
In order to minimize the convergence time, Alcatel-Lucent’s PBB implementation offers the
selection of a mode where B-VPLS forwarding reverts for a short time to flooding so that MMRP
has enough time to converge. This mode can be selected through configuration using the
configure>service>vpl> bvpls>mrp>flood-time value command where value represents the
amount of time in seconds that flooding will be enabled. Refer to the PBB Command Reference
on page 825 for command syntax and usage.
If this behavior is selected, the forwarding plane reverts to B-VPLS flooding for a configurable
time period, for example, for a few seconds, then it reverts back to the MFIB entries installed by
MMRP.
The following B-VPLS events initiate the switch from per I-VPLS (MMRP) MFIB entries to “B-
VPLS flooding”:
• Reception or local triggering of a TCN
• B-SAP failure
• Failure of a B-SDP binding
• Pseudowire activation in a primary/standby HVPLS resiliency solution
• SF/CPM switchover due to STP reconvergence
Controlling MRP Scope using MRP Policies
MMRP advertises the Group BMACs associated with ISIDs throughout the whole BVPLS context
regardless of whether a specific IVPLS is present in one or all the related PEs or BEBs. When
evaluating the overall scalability the resource consumption in both the control and data plane must
be considered:
• Control plane - MMRP processing and number of attributes advertised
• Data plane – one tree is instantiated per ISID or Group BMAC attribute
In a multi-domain environment, for example multiple MANs interconnected through a WAN, the
BVPLS and implicitly MMRP advertisement may span across domains. The MMRP attributes
will be flooded throughout the BVPLS context indiscriminately, regardless of the distribution of
IVPLS sites.
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