Pseudowire Redundancy
Page 130 7750 SR OS Services Guide
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:
• There are two different destination 7x50 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 7x50 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 7x50 pseudowire
switching node fails. The 7x50 supports pseudowire switching.
VLL Resilience with Two Destination PE Nodes
Figure 24 illustrates the application of pseudowire redundancy to provide Ethernet VLL service
resilience for broadband service subscribers accessing the broadband service on the service
provider BRAS.
Figure 11: VLL Resilience
IP/MPLS
7450 ESS
PE 2
PE 3
PE 1
Eth SAP
Eth SAP
(standby)
Eth SAP
(primary)
Primary Eth
Standby
backup Eth
PW
DSLAM
BRAS 1
7450 ESS
7450 ESS
OSSG115
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