TDM Cable Detect Feature Overview

Introduction

This document describes how to the use the cable detect feature in order to verify the presence of physical cables that are connected to the Foreign Exchange Office (FXO) or Foreign Exchange Station (FXS) port of the Cisco TDM.

Cable Detect Feature Overview

The cable detect feature was introduced in Cisco IOS^® Version 15.1(1)T. This feature is used in order to verify the presence of a physical cable that is connected to an FXO or FXS port. This feature works in two different ways, based on the IOS version that is used.

The next sections describe the way that this feature functions and the various commands and outputs of which you should be mindful.

Cable Detect Feature Functionality

This section describes how to implement and use the cable detect feature.

IOS Versions Earlier than Version 15.2(4)M

The cable detect feature notifies you through the use of syslog messages and/or a change in the operational status of a port, which can be observed in the show voice port summary command output.

This table lists the notification types for different types of ports:

PORT	SYSLOG MESSAGE	SHOW VOICE PORT SUMMARY
FXO-LS	YES	YES
FXO-GS	YES	NO
FXS-LS	YES	NO
FXS-GS	YES	NO

In order to activate the cable detect feature for an FXO or FXS port, configure the cable-detect command for the voice-port section:

voice-port 0/1/1cable-detect

The cable detect feature works automatically through a poll mechanism that runs every 15 seconds. A syslog message is generated and a change occurs in the show voice port summary command output when there is a cable removal from or connection to the port.

Without the cable detect feature configured, this show voice port summary command output is observed (as long as the voice-port is administratively active):

show voice port summary
                                         IN      OUT
     PORT    CH   SIG-TYPE  ADMIN OPER STATUS   STATUS    EC
     =============== == ============ ===== ==== ======== ======== 
     0/0/0   --    fxs-ls    up   dorm  on-hook  idle      y 
     0/0/1   --    fxs-ls    up   dorm  on-hook  idle      y 
     0/0/2   --    fxs-ls    up   dorm  on-hook  idle      y  
     0/0/3   --    fxs-ls    up   dorm  on-hook  idle      y 
     0/1/0   --    fxo-ls    up   dorm  idle    on-hook    y 
     0/1/1   --    fxo-ls    up   dorm  idle    on-hook    y 
     0/1/2   --    fxo-ls    up   dorm  idle    on-hook    y 
     0/1/3   --    fxo-ls    up   dorm  idle    on-hook    y 

When the cable detect feature is configured, the output appears to be the same when the cable is connected to a port:

show voice port summary
                                           IN      OUT
     PORT    CH   SIG-TYPE  ADMIN OPER  STATUS   STATUS   EC
     =============== == ============ ===== ==== ======== ======
     0/0/0    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/0/1    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/0/2    --    fxs-ls    up   dorm  on-hook  idle     y  
     0/0/3    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/1/0    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/1    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/2    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/3    --    fxo-ls    up   dorm   idle   on-hook   y 

When the cable detect feature is configured and a cable is removed from a port, then changes appear. For example, if a cable is removed from Port 0/1/1, a syslog message such as this is generated:

*Oct 28 07:23:15.879: %LINK-3-UPDOWN: Interface Foreign Exchange Office 0/1/1,
 changed state to operational status down due to cable removal

Also, these changes in the show voice port summary command output are observed:

show voice port summary
                                        IN       OUT
    PORT    CH   SIG-TYPE  ADMIN OPER  STATUS   STATUS    EC
    =============== == ============ ===== ==== ======== ========
    0/0/0   --    fxs-ls    up   dorm  on-hook  idle       y 
    0/0/1   --    fxs-ls    up   dorm  on-hook  idle       y 
    0/0/2   --    fxs-ls    up   dorm  on-hook  idle       y  
    0/0/3   --    fxs-ls    up   dorm  on-hook  idle       y 
    0/1/0   --    fxo-ls    up   dorm   idle   on-hook     y 
    0/1/1   --    fxo-ls    up   down   idle   off-hook    y 
    0/1/2   --    fxo-ls    up   dorm  idle    on-hook     y 
    0/1/3   --    fxo-ls    up   dorm  idle    on-hook     y 

Note: The operational status (OPER) changes to down, and the output status (OUT STATUS) changes to off-hook.

When a cable is reconnected to the port from which it was removed, changes are observed.

This is the syslog message that is generated:

*Oct 28 07:24:15.856: %LINK-3-UPDOWN: Interface Foreign Exchange Office 0/1/1,
 changed state to operational status up due to cable reconnection

The show voice port summary command output reverts to the output that is originally observed:

show voice port summary
                                           IN      OUT
     PORT    CH   SIG-TYPE  ADMIN OPER  STATUS   STATUS   EC
     =============== == ============ ===== ==== ======== ======
     0/0/0    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/0/1    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/0/2    --    fxs-ls    up   dorm  on-hook  idle     y  
     0/0/3    --    fxs-ls    up   dorm  on-hook  idle     y 
     0/1/0    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/1    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/2    --    fxo-ls    up   dorm   idle   on-hook   y 
     0/1/3    --    fxo-ls    up   dorm   idle   on-hook   y 

IOS Versions 15.2(4)M and Later

The functionality of the cable detect feature is modified in Cisco IOS Versions 15.2(4)M and later.

With these modifications, only syslog messages are displayed as a notification for changes in the cable detection status. There are no changes reflected in the output of the show voice port summary command. Also, unlike earlier versions, the syslog messages do not appear automatically when the cable detect feature is configured for the voice-port segment.

In order to automate this process, you must include the cable-detect-poll-timer command for the voice service pots segment:

voice service pots
 cable-detect-poll-timer <time in minutes>

This command enables the cable detect feature to automatically poll the port every so often, as defined, and generate a syslog message if a change detected from the previous poll.

Caution: Cisco recommends that the cable detect polls be used minimally, since call disruption might occur when a port is polled.

This syslog message is now observed when a cable is removed:

*Oct 31 09:20:19.091: %HTSP-5-VPM_CABLE_STAT: voice port Foreign Exchange
 Station 0/1/1: cable removed

This syslog message is now observed when a cable is replaced:

*Oct 31 02:00:32.399: %HTSP-5-VPM_CABLE_STAT: voice port Foreign Exchange
 Office 0/2/1: cable reconnected

If the cable detect poll timer is not configured, then the cable detect poll does not occur automatically. When you want to verify the status of these ports in regards to cable detection, you must enter the show voice cable all command. This command is used in order to present the current cable detection status of the ports for which the cable detect feature is configured, and the syslog messages that correspond are generated if there is a change in the status of these ports.

This snippet provides an example of the show voice cable-status all command output:

Caution: This command might take a longer period of time to perform and might cause call disruption.

#show voice cable-status all

     PORT         cable-status
     ========== ================
     0/1/0        cable-detect not configured
     0/1/1        cable-detect not configured
     0/2/0        cable-detect not configured
     0/2/1        not connected
 
 *Oct 31 01:57:56.259: %HTSP-5-VPM_CABLE_STAT: voice port Foreign Exchange
 Office 0/2/1: cable removed

In order to verify the previous poll data for these ports, enter the show voice cable-status summary command:

#show voice cable-status summary
 
     PORT         cable-status
     ========== ================
     0/0/0        cable-detect not configured
     0/0/1        cable-detect not configured
     0/0/2        cable-detect not configured
     0/0/3        cable-detect not configured
     0/1/0        cable-detect not configured
     0/1/1        cable-detect not configured
     0/1/2        cable-detect not configured
     0/1/3        cable-detect not configured

IOS Version 15.3(3)M1

With Cisco IOS Version 15.3(3)M1, exclusively available for the Cisco G2 Series Integrated Services Router (ISR), an extension of the cable detect command, cable-detect busyout-state, is included. This command helps to reflect changes in the voice-port cable detection state in the show voice port summary command output.

This command can be added for the voice-port segment:

voice-port 0/1/1
 cable-detect busyout-state

This configuration also affects the show voice port summary command output:

                                     IN      OUT
  PORT    CH   SIG-TYPE  ADMIN OPER STATUS   STATUS   EC
 =============== == ============ ===== ==== ======== ===
  0/2/0   --   fxo-ls    up    dorm  idle   on-hook   y
  0/2/1   --   fxo-ls    up    down  idle   off-hook  y  
  0/2/2   --   fxo-ls    up    dorm  idle   on-hook   y
  0/2/3   --   fxo-ls    up    dorm  idle   on-hook   y

Note: This output is observed after the cable-detect busyout-state is configured and the cable is not connected to Port 0/2/1.