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Cisco 6700 Series Multiservice Access Platforms

Field Notice: *Expired* FN - 12913 - GR-303 Call Processing Characterized by Loss of Dial Tone


Revised December 6, 2006

October 5, 2000

NOTICE:

THIS FIELD NOTICE HAS BEEN ARCHIVED AND IS NO LONGER MAINTAINED OR UPDATED BY CISCO.

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE, WARRANTY OR SUPPORT. USE OF THE INFORMATION ON THIS FIELD NOTICE OR MATERIALS LINKED FROM THIS FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.


Products Affected

Product

Comments

6732

 

Problem Description

When connected to an unterminated T1 line, the Timeslot Management Channel (TMC) of the Cisco 6732 detects erroneous AB bits off-hook conditions from the remote T1 interface. These off-hook conditions may lead to an excessive number of setup requests from the TMC to the Class 5 switch, causing the TMC link to freeze.

Background

If you suspect an unterminated T1 line is causing GR-303 problems, examine the Element Management System (EMS) alarm log and look for the following alarms repeating every 1-2 seconds for a single facility (port) of a single T1 line card:

  1. DSX1/T1 Near End AIS (Receive)

  2. DSX1/T1 Near End Loss of Frame (Receive)

  3. DSX1/T1 Far End Failure

  4. DSX1/T1 Near End Loss of Signal (Receive)

Problem Symptoms

Off-hook conditions may lead to an excessive number of setup requests from the TMC to the Class 5 switch, causing the TMC link to freeze. You can detect an unterminated T1 line in the EMS alarm log. With the TMC link frozen, the 6732 repeatedly issues an alarm and clears the alarm shortly thereafter, generating a high volume of alarm log entries for the T1.

Workaround/Solution

Cisco Systems recommends that an unterminated T1 line within the network be placed out-of-service immediately, as shown within the Cisco EMS line provisioning screen below. Once the unterminated T1 is out-of-service, provision the T1 from the T1 interface through the 6732 chassis to the Class 5 switch. Only after the T1 has been provisioned from the 6732 (central office) to the customer premises equipment (CPE), should you place the T1 in-service.

fn12913a.gif

After correctly provisioning the T1 and placing it in-service, perform a Main Control Card (MCC) switchover on the 6732 chassis to restore the TMC link.

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:

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