Active/Standby Mode For Pseudowire Redundancy (Standby Signaling); Figure 38: Active/Standby Mode For Redundant Pseudowires - Alcatel-Lucent 7705 Service Manual

Active/Standby Mode for Pseudowire Redundancy
(Standby Signaling)
Pseudowire redundancy as described in the previous section operates in active/active mode;
that is, the primary pseudowire is up and ready to transmit and receive traffic, and the
secondary pseudowire is up and ready to receive traffic. In
were active, this mode of operation would offer seamless redundancy in most cases.
However, this mode could also potentially stress the IGP; for example, in active/active mode
the number of routes advertised is greater than in active/standby mode. Another example is
the duplication of Ethernet control frames to the 7705 SAR from a VPLS or VPRN service
on an SR node through both primary and secondary VLLs.
Active/standby mode is introduced to address these issues. Active/standby mode is also
referred to as standby signaling. Standby signaling is supported on all VLLs: Apipes,
Cpipes, Epipes, and Ipipes.
In
VPLS service) on an SR node. If standby signaling status is configured on one of the
pseudowires, this information is transmitted to the SR. The SR node can then either
withdraw the associated IP interface or routes or shut down the spoke SDP toward the SAR
when the SR receives the standby status message. These actions avoid the problem of
duplicate routes being sent to the SR node.
It is also necessary that the CE connected to the redundant pseudowire endpoint on the
7705 SAR node be aware that the link to the far-end node is currently not active.
7705 SAR OS Services Guide

Figure 38: Active/Standby Mode for Redundant Pseudowires

7705 SAR
Figure 38, the redundant pseudowires are terminated on a VPRN SAP (could also be a
Backhaul
Infrastructure
VLL-P
VLL-S
LER
VLL Services
Figure 38, if both pseudowires
VPRN
route-1
SR-1
LER/PE
VPRN
SR-3
route-1
VPRN
SR-1
LER/PE
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