Vpls Redundancy; Spoke Sdp Redundancy For Metro Interconnection - Alcatel-Lucent 7750 SR OS Service Manual

VPLS Features

VPLS Redundancy

The VPLS draft standard (draft-ietf-l2vpn-vpls-ldp, Virtual Private LAN Services over MPLS)
includes provisions for hierarchical VPLS, using point-to-point spoke SDPs. Two applications
have (so far) been identified for spoke SDPs:
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•
In both applications the spoke SDPs serve to improve the scalability of VPLS.
While node redundancy is implicit in non-hierarchical VPLS services (using a full mesh of SDPs
between PEs), node redundancy for spoke SDPs needs to be provided separately.
Alcatel-Lucent routers have implemented special features for improving the resilience of
Hierarchical VPLS instances, in both MTU and inter-metro applications.

Spoke SDP Redundancy for Metro Interconnection

When two or more meshed VPLS instances are interconnected by redundant spoke SDPs (as
shown in
topology, Spanning Tree Protocol (STP) can be run over the SDPs (links) which form the loop
such that one of the SDPs is blocked. As running STP in each and every VPLS in this topology is
not efficient, the 7750 SR includes functionality which can associate a number of VPLSes to a
single STP instance running over the redundant-SDPs. Node redundancy is thus achieved by
running STP in one VPLS, and applying the conclusions of this STP to the other VPLSes. The
VPLS instance running STP is referred to as the 'management VPLS' or mVPLS.
In the case of a failure of the active node, STP on the management VPLS in the standby node will
change the link states from disabled to active. The standby node will then broadcast a MAC flush
LDP control message in each of the protected VPLS instances, so that the address of the newly
active node can be re-learned by all PEs in the VPLS.
It is possible to configure two management VPLSes, where both VPLSes have different active
spokes (this is achieved by changing the path-cost in STP). By associating different user VPLSes
with the two management VPLSes, load balancing across the spokes can be achieved.
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to connect to Multi-Tenant Units (MTUs) within a metro area network;
to interconnect the VPLS nodes of two metro networks.
Figure 38), a loop in the topology results. In order to remove such a loop from the
7750 SR OS Services Guide