Virtual Private LAN Services
7750 SR OS Services Guide Page 351
Figure 6: HVPLS with Spoke Redundancy
SAP Redundancy for MTU Protection
MAC Flush with STP
A second application of Hierarchical VPLS is in the use of Multi Tenant Units (MTU). MTUs are
typically not MPLS-enabled, and thus have Ethernet links to the closest PE node (see Figure 39
below). To protect against failure of the PE node, an MTU could be dual-homed and thus have two
SAPs on two PE nodes. To resolve the potential loop, STP is activated on the MTU and the two
PEs.
Like in the scenario above, STP only needs to run in a single VPLS instance, and the results of the
STP calculations are applied to all VPLSes on the link. Equally, the standby node will broadcast
MAC flush LDP messages in the protected VPLS instances when it detects that the active node
has failed.
= Metro IP/MPLS Network
MPLS Transit
Network
MPLS Tunnel
Spoke
Spoke
= Full Mesh
OSSG045
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