Field Notice 12162: DS3-12 - Incorrect Coding in C2 Byte of Optical Backbone Facility

April 13, 2000

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Products Affected

Problem Description

When receiving Synchronous Transport Signal (STS) timeslots carrying asynchronous DS3s on the optical backbone facility, such as OC12 and OC48, certain vendors may insert a value 0x01 (equipped-non specific payload) into the C2 byte in the Synchronous Optical NETwork (SONET) STS path overhead. The C2 label, in this example, would indicate that there is DS3 traffic in the Synchronous Payload Envelope (SPE), but it is not defined as asynchronous DS3.

Background

This problem was discovered during interoperability testing in the field by Cisco Optical Transport field engineers.

Problem Symptoms

When receiving other vendors SONET STS signal with embedded DS3 traffic in the payload (SPE), the Cisco 15454 will read the C2 byte to determine the contained payload. The information being carried in the SPE may be valid, but the SONET STS PATH overhead C2 byte will be read as being equipped non-specific. per Telcordia (Bellcore) GR-253. This will cause the corresponding STS timeslot to report Payload Label Mismatch-Path (PLM-P) and the associated DS3 facility to transmit Alarm Indication Signal (AIS).

Workaround/Solution

The workaround for this type of problem will be to upgrade to maintenance release 2.0.1 for the Cisco 15454.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

• Open a service request on Cisco.com
• By email
• By telephone