Nortel Networks NTRN10AN, 3500 manual ’Infinite wait-to-restore’ parameter

2-12Operation, administration, and maintenance (OAM) features

Lockout of working: prevents a protection switch of the working line to the protection line.

Lockout of protection: prevents any of the channels from switching to the protection line.

Automatically initiated BLSR switching requests

•Signal fail (SF)

—SF is a hard failure caused by a Loss of Signal, Loss of Frame, a line BER exceeding a preselected threshold, a line AIS, or some other protectable hard failure. All channels with the SF condition are protected using the ring switch.

•Signal degrade (SD)

—SD is a soft failure caused by a BER exceeding a preselected threshold. It can be used to detect gradual degradation of service to perform preventive maintenance. All degraded lines are protected using the ring switch.

•Reverse request (RR)

—RR is transmitted to the tail-end network element on the Short Path as an acknowledgement for receiving the Short Path ring bridge request.

•Wait to restore (WTR)

—WTR is issued when working channels meet the restoral threshold after an SD or SF condition. This request is used to maintain the current state during the WTR period unless it is pre-empted by a higher priority request.

When a failure occurs in the ring, the ring switches are performed by the nodes immediately adjacent to the failed segment. It should be noted that a failed segment may be a single span or many spans with multiple nodes.

For a 2-Fiber BLSR operating at an OC-48 rate, time slot numbers 1 through 24 at the multiplex input are reserved for working channels. Time slot number ‘X’ of the first fiber is protected using time slot number ‘X + 24’ of the second fiber in the opposite direction, where X is an integer between 1 and 24.

Similarly, for a 2-Fiber BLSR operating at an OC-192 rate, time slot numbers 1 through 96 at the multiplex input are reserved for working channels. Time slot number ‘X’ of the first fiber is protected using time slot number ‘X + 96’ of the second fiber in the opposite direction, where X is an integer between 1 and 96.

’Infinite wait-to-restore’ parameter

OPTera Metro 3500 allows users to provision an infinite wait-to-restore period in BLSR-protected optical interfaces. This effectively allows users to provision BLSRs to autonomously switch non-revertively.

OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004