Nortel Networks 3500, NTRN10AN manual Protection, User-initiated Blsr switching commands

Operation, administration, and maintenance (OAM) features 2-11

A BLSR offers a network-level protection capability, and differs from a UPSR in that the nodes in a BLSR are aware of the larger configuration. In a BLSR, switching nodes communicate to each other through K-bytes. A UPSR node has no network knowledge and does not rely upon any APS communication with other nodes.

Protection

Protection in a BLSR is provided by using a time slot select function. The network elements adjacent to the protected span bridges the working time slots in the failed direction to the preassigned protection time slots in the direction away from the failure. The network element where the signal is dropped from the ring receives (selects) from the protection time slots on the side away from the failure.

A BLSR bridge request can be initiated either by an operator or autonomously.

Note: All user-initiated protection switching commands are signaled on the APS channels (K1 and K2 bytes).

User-initiated BLSR switching commands

•Forced switch

—This command performs the ring switch from the working to the protection channels for the span between the node at which the command is initiated and the adjacent node to which the command is destined. This switch occurs regardless of the state of the protection channels, unless the protection channels are satisfying a higher priority request.

•Manual switch

—This command performs the ring switch from the working to the protection channels for the span between the node at which the command was initiated and the node to which the command was destined. This occurs if the protection channels to be used are operating at a BER better than the signal degrade threshold and are not satisfying an equal or higher priority request (including failure of the protection channels).

•Lockout of working/protection

—These command performs a lockout (working or protection) which prevents the working line from switching to the protection line. When you perform a lockout, you prevent traffic from switching to the protection line. If traffic is on the protection line, it returns to the working line regardless of the condition of the working line. After you initiate a lockout request, the lockout request remains active until you release it. The lockout command has the highest priority.

Planning and Ordering Guide—Part 1 of 2 NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004