Alcatel-Lucent 7750 SR Manual page 795

Os services guide

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Another case is when the QinQ access network dual-homed to a PBB PE uses RSTP or MVPLS

with MSTP to provide loop avoidance at the interconnection between the PBB PEs and the QinQ

SWs. In the case where the access topology changes, a TCN event will be generated and

propagated throughout the access network. Similarly, this change needs to be propagated to the

remote PBB PEs to avoid blackholing.

A solution is required to propagate the I-VPLS events through the backbone infrastructure (B-

VPLS) in order to flush the customer MAC to BMAC entries in the remote PBB. As there are no

IVPLS control plane exchanges across the PBB backbone, extensions to B-VPLS control plane

are required to propagate the I-VPLS MAC flush events across the B-VPLS.

LDP MAC Flush Solution for PBB Blackholing

In the case of an MPLS core, B-VPLS uses T-LDP signaling to set up the pseudowire forwarding.

The following I-VPLS events must be propagated across the core B-VPLS using LDP MAC

flush-all-but-mine or flush-all-from-me indications:

For flush-all-but-mine indication ("positive flush"):

For flush-all-from-me indication ("negative flush")

In order to propagate the MAC flush indications triggered by the above events, the PE that

originates the LDP MAC withdraw message must be identified. In regular VPLS "mine"/"me" is

represented by the pseudowire associated with the FEC and the T-LDP session on which the LDP

MAC withdraw was received. In PBB, this is achieved using the B-VPLS over which the signaling

was propagated and the BMAC address of the originator PE.

Alcatel-Lucent PBB-VPLS solution addresses this requirement by inserting in the BVPLS LDP

MAC withdraw message a new PBB-TLV (type-length-value) element. The new PBB TLV

contains the source BMAC identifying the originator ("mine"/"me") of the flush indication and

the ISID list identifying the I-VPLS instances affected by the flush indication.

7750 SR OS Services Guide

TCN event in one or more of the I-VPLS or in the related M-VPLS for the MSTP use

Pseudowire/SDP binding activation with Active/Standby pseudowire (standby, active or

Reception of an LDP MAC withdraw "flush-all-but-mine" in the related I-VPLS

MC-LAG failure - does not require send-flush-on-failure to be enabled in I-VPLS

Failure of a local SAP – requires send-flush-on-failure to be enabled in I-VPLS

Failure of a local pseudowires/SDP binding – requires send-flush-on-failure to be enabled

Reception of an LDP MAC withdraw "flush-all-from-me" in the related I-VPLS

Virtual Private LAN Services