Conversely, in nonrevertive mode, when traffic is active on the protection line and the
working line becomes operational, traffic will remain on the protection line (until either
manual intervention or a failure on the protection line forces a switch back to the
working line).
APS Network Configuration Options
Three basic APS configurations are supported:
• Two-switch configuration, where the working line is terminated in one
BlackDiamond switch and the protection line is terminated in another.
• Two-module configuration, where the working line and the protection line are
terminated in two different SONET modules that reside in the same BlackDiamond
chassis.
• Single-module configuration, where the working line and the protection line are
terminated in the same BlackDiamond SONET module.
Because the two-switch configuration is the most advanced, it is discussed first,
followed by the two simpler configurations.
In the two-switch configuration (see Figure 3-13), the two BlackDiamond switches form
a virtual APS switch. The PoS interface in BlackDiamond #1 is configured to be the
working line, while the PoS interface in BlackDiamond #2 is configured to be the
protection line. The same IP address is configured for both PoS interfaces. In this
example, the common IP address is 192.168.10.1. The use of a common IP address
enables the neighboring PPP router to view the virtual APS switch as a single router
entity; the neighboring router is unaware that its partner is actually two cooperating
switches. Figure 3-14 illustrates the logical PPP connectivity between the virtual APS
router and the neighboring PPP router.
Note: The two-switch configuration is supported only if PPP is configured on the
PoS ports. The two-switch configuration is not supported if HDLC tunneling is
configured on the PoS ports.
Packet Over SONET Module Installation and User Guide
Configuring and Monitoring APS Functions
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