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Configuring Automatic Protect Switching


To configure basic Automatic Protection Switching (APS) options:

  1. In configuration mode, go to the [edit interfaces so-fpc/pic/port sonet-options aps] hierarchy level.
  2. Configure the APS interval at which the protect and working routers send packets to their neighbors to advertise that they are operational. A router considers its neighbor to be operational for a period, called the hold time, that is, by default, three times the advertisement interval. You can set the APS interval from 1 through 65,534 milliseconds. By default, 1000 milliseconds is set.
  3. Configure the annex-b option for Multiplex Section Protection (MSP) switching on SDH interfaces for M320 and M120 routers only.
  4. Configure the Automatic Protection Switching (APS) authentication key (password).
  5. Configure the fast-aps-switch option to reduce the Automatic Protection Switching (APS) switchover time in Layer 2 circuits in M320 routers with Channelized OC3/STM1 Circuit Emulation PIC with SFP only.
  6. Configure the force option to either protect mode or working mode to perform a forced switch between the protect and working circuits. This statement is honored only if there are no higher-priority reasons to switch. It can be overridden by a signal failure on the protect circuit, thus causing a switch to the working circuit.
  7. Configure the hold-time value in milliseconds to determine whether a neighbor APS router is operational where the hold-time value ranges from 1 through 65,354 milliseconds. By default, 3000 milliseconds (3 times the advertisement interval) is set as hold time value.
  8. Configure a lockout of protection, forcing the use of the working circuit and locking out the protect circuit regardless of anything else.
  9. Configure the address of the remote interface when you are configuring one router to be the working router and a second to be the protect router. You can configure this on one or both of the interfaces.
  10. Configure load sharing between two working protect circuit pairs where circuit’s group name is as configured with the protect-circuit or working-circuit statement.
  11. Configure the protect router in an APS circuit pair. When the working interface fails, APS brings up the protection circuit and the traffic is moved to the protection circuit.
  12. Configure the request option as protect circuit or working circuit to perform a manual switch between the protect and working circuits. This statement is honored only if there are no higher-priority reasons to switch.
  13. Configure APS revertive mode in seconds ranging from 1 through 65,535 seconds which denotes the time to wait after the working circuit has again become functional before making the working circuit active again. By default, APS operates in nonrevertive mode.
  14. Configure the interface in bidirectional mode or in unidirectional mode. By default, if the switching-mode statement is not configured, the mode is bidirectional, and the interface does not interoperate with a unidirectional SONET/SDH LTE.
  15. Configure the working router in an APS circuit pair.