Pseudowire Redundancy; Figure 23: Vll Resilience - Alcatel-Lucent 7210 SAS M Service Manual

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Pseudowire Redundancy

Pseudowire redundancy provides the ability to protect a pseudowire with a pre-provisioned

pseudowire and to switch traffic over to the secondary standby pseudowire in case of a SAP and/or

network failure condition. Normally, pseudowires are redundant by the virtue of the SDP

redundancy mechanism. For instance, if the SDP is an RSVP LSP and is protected by a secondary

standby path and/or by Fast-Reroute paths, the pseudowire is also protected. However, there are a

couple of applications in which SDP redundancy does not protect the end-to-end pseudowire path:

Pseudowire and VPLS link redundancy extends link-level resiliency for pseudowires and VPLS to

protect critical network paths against physical link or node failures. These innovations enable the

virtualization of redundant paths across the metro or core IP network to provide seamless and

transparent fail-over for point-to-point and multi-point connections and services. When deployed

with multi-chassis LAG, the path for return traffic is maintained through the pseudowire or VPLS

switchover, which enables carriers to deliver "always on" services across their IP/MPLS networks.

If the Ethernet SAP on PE2 fails, PE2 notifies PE1 of the failure by either withdrawing the

primary pseudowire label it advertised or by sending a pseudowire status notification with the

code set to indicate a SAP defect. PE1 will receive it and will immediately switch its local SAP to

7210 SAS M Services Guide

There are two different destination PE nodes for the same VLL service. The main use case

is the provision of dual-homing of a CPE or access node to two PE nodes located in

different POPs. The other use case is the provision of a pair of active and standby BRAS

nodes, or active and standby links to the same BRAS node, to provide service resiliency to

broadband service subscribers.

The pseudowire path is switched in the middle of the network and the SR-Series

pseudowire switching node fails.

Virtual Leased Line Services

OSSG115-7210M

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