Cisco Systems MGX 8230 Automatic Protection Switching on the PXM1

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Cisco MGX 8230 Edge Concentrator Installation and Configuration

Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001

Chapter6 Card and Service Configuration The Processor Switching Module

UNI cell headers typically apply where a workstation connects through a line to a PXM1 UNI port

(rather than a SLIP-based port on the PXM1-UI card). Such an implementation is not common, so

cnfatmln usually is not necessary.

Automatic Protection Switching on the PXM1

Automatic Protection Switching (APS) provides redundancy for an OC-3 or OC-12 line on the PXM1

(if a failure occurs someplace other than the PXM1 front card). The fai lure can originate on the daughter

card, uplink card, or any part of the physical line.

With APS, the active PXM1 remains act ive an d pa ss es the cells from the failed lin e- pa th t hro ug h th e

redundant line. The advanta ge of APS is that a line sw itchover requires significant ly less time than a full

PXM1 switchover.

Note A failure of the PXM1 front card in a re du n da nt sy stem causes the entire PXM1 ca rd se t to switch

over.

As defined in GR-253, a variety of A P S m o d ali ti es are possible (see the command sum maries that

follow).

The current requirements for APS service on an MGX 8230 shelf are:

•Redundant PXM1s (currently, the PXM1 does not support an APS configuration where the working

and protection lines o n th e sa me uplink card).

•A “B” version of an OC-3 or OC-12 back card (SMLR-1-622/B, and so on).

•The connected network shelf or CPE must also support APS.

Initial APS specification c onsists of the working and protection slot and lin e and the mode for APS. After

the initial APS specification, you can configure additional APS parameters, give commands for

switching lines, and display th e APS configuration. The Cisc oView application and CLI provide acce ss

to the APS feature. For detailed descr iptions of the CLI commands, se e the Cisco MGX 8230 Wide Area

Edge Switch Command R e fe renc e. Note that APS is available for o n ly th e “B” versions of the SONET

cards—SMLR-1-622/B, and so on. Th e ap pl ica bl e C L I c ommands are:

•addapsln to specify the lines and mode for APS

•cnfapsln to modify the following details of APS operation:

–

error thresholds

–

wait period before the P XM 1 r es t or es the working line after err o r s cl ear

–

unidirectional or bidirectional switchover, which specifies whether one or both directions of a

line are switched when the crit eria for a hard or soft failure are met f or one direction

–

revertive recovery, where the working line automatica lly returns to operation after er ror s cl ear

and any wait period has elapsed