Specifications

1-5
Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 1 Alarm Troubleshooting
1.3.3 AIS-P
• Not Reported (NR) (Condition)
The ONS 15454 detects an alarm indication signal (AIS) in the SONET overhead. This alarm is
secondary to another alarm occurring simultaneously in an upstream node. The AIS is caused by an
incomplete circuit path, for example, when the port on the reporting node is in-service, but a node
upstream on the circuit does not have its port in-service. The upstream node often reports a LOS or has
an OC-N port out of service. The AIS-P clears when the primary alarm on the upstream node is cleared.
However, the node with the primary alarm may not report any alarms to indicate it is at fault.
AIS-P occurs in each node on the incoming OC-N path. The path layer is the segment between the
originating equipment and the terminating equipment. This path segment encompasses several
consecutive line segments or segments between two SONET devices. The originating equipment puts
bits together into a SONET payload and the terminating equipment breaks the bits apart again. SONET
multiplexers, such as the ONS 15454, often perform the origination and termination tasks of the SONET
payload.
Procedure: Clear the AIS-P Condition
Step 1 Check upstream nodes and equipment for alarms, especially LOS and out-of-service ports.
Step 2 Clear the upstream alarms.
1.3.4 AIS-V
• Not Reported (NR)
The ONS 15454 detects an alarm indication signal (AIS) in the SONET overhead. This alarm is
secondary to another alarm occurring simultaneously in an upstream node. An incomplete circuit path
causes an AIS, for example, when the port on the reporting node is in-service but a node upstream on
the circuit does not have its OC-N port in-service. The upstream node often reports a LOS or has an
out-of-service port. The AIS-V clears when the primary alarm is cleared. The node with the
out-of-service port may not report any alarms to indicate it is at fault.
An AIS-V indicates that an upstream failure occurred at the virtual tributary (VT) layer. The VT, or
electrical layer, is created when the SONET signal is broken down into an electrical signal, for example
when an optical signal comes into an ONS 15454 OC-N card. If this optical signal is demultiplexed by
the ONS 15454, and one of the channels separated from the optical signal is then cross-connected into
the DS-1 ports in the same node, that ONS 15454 reports an AIS-V alarm.
An AIS-V error message on the electrical card is accompanied by an AIS-P error message on the
cross-connected OC-N card.
Note See the “AIS-V on DS3XM-6 Unused VT Circuits” section on page 2-27 for AIS-Vs that occur on
DS3XM-6 unused VT circuits.