Cisco 6000 Series IP DSL Switches

Field Notice: CPE Performance Issues When Using Overhead Framing Modes 0, 1 and 2

October 8, 2001

Products Affected


Problem Description

The customer premises equipment (CPE) does not train or perform reliably when the Discrete Multitone (DMT) profile is set to use overhead framing modes 0, 1, or 2.


Overhead framing modes 0, 1, and 2 are not supported at this time.

Problem Symptoms

The customer experiences unreliable performance with the CPE, or the CPE does not train consistently.


Overhead framing mode 3 is designed for use in Asynchronous Transfer Mode (ATM), while overhead framing mode 1, which is not currently supported, is designed for Synchronous Transport Module (STM) mode. Customers should configure their profiles to use overhead framing mode 3. Also, using overhead framing mode 3 only uses 32 bytes of administrative overhead, and it allows more bandwidth to be allocated to user data, relative to overhead framing mode 1.

Cisco IOS Versions Affected

All Cisco IOS® Software versions are affected.

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: