ISDN Voice Configuration Guide, Cisco IOS Release 15M&T
Clear Channel T3 E3 with Integrated CSU DSU
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Clear Channel T3 E3 with Integrated CSU DSU

Contents

Clear Channel T3 E3 with Integrated CSU DSU

This chapter describes how to implement the Clear Channel T3/E3 with Integrated CSU/DSU feature. The feature delivers Clear Channel service as a T3/E3 pipe with bandwidth of 28x24x64k for T3 or 16x32x64 for E3. The software-configurable T3/E3 network module allows you to switch between T3 and E3 applications with a single Cisco IOS command.

The T3/E3 NM-1 network module supports a single-port T3 or E3 with an integrated channel service unit (CSU) and a data service unit (DSU). It supports High-Level Data Link Control (HDLC), PPP, and frame relay. It includes the following features:

  • Single port--universal T3/E3 version
  • Clear and subrate support on both T3 and E3 modes
  • Online insertion and removal (OIR) support on Cisco 3660 series and Cisco 3745 routers
  • Onboard processing of Cisco Message Definition Language (MDL) and performance monitoring
  • Support for scrambling and subrate can be independently or simultaneously enabled in each DSU mode
  • Support for full T3 and E3 line rates

The T3/E3 NM-1 network module provides high-speed performance for advanced, fully converged networks supporting a wide array of applications and services such as security and advanced QoS for voice and video. T3/E3 and subrate T3/E3 connectivity optimizes WAN bandwidth for deploying the new applications and service delivery.

Feature History for Clear Channel T3/E3 with Integrated CSU/DSU

Release

Modification

12.2(11)YT

This feature was introduced.

12.2(15)T

This feature was integrated into this release.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Clear Channel T3 E3 with Integrated CSU DSU

  • Perform the prerequisites that are listed in the "Prerequisites for Configuring an ISDN Voice Interface" section.
  • Ensure that you have sufficient system memory (see the table below).
Table 1 Minimum Memory Requirements

Platform

Flash Memory

DRAM Memory

Cisco 2650

8 MB

32 MB

Cisco 2651XM

Cisco 2691

32 MB

64 MB

Cisco 3660 series

8 MB

64 MB

Cisco 3725

32 MB

128 MB

Cisco 3745

32 MB

128 MB

Restrictions for Clear Channel T3 E3 with Integrated CSU DSU

Restrictions are described in the "Restrictions for Configuring ISDN Voice Interfaces" section.

Information About Clear Channel T3 E3 with Integrated CSU DSU

All supported platforms are capable of supporting line-rate performance, but impose varying levels of CPU overhead and therefore affect overall platform performance. The table below shows recommended branch-office positioning.

Table 2 T3/E3 NM-1 Branch Office Positioning and Support Comparison

Platform

Recommended Positioning

Supported T3/E3 Modes

Type of Service

Branch Office Size

Cisco 2650

Subrate T3/E3

Small to medium offices

1

Cisco 2651XM

Cisco 2691

Subrate T3/E3

Small to medium offices

1

Cisco 3660 series

Subrate and full-rate T3/E3

Large and regional offices

1

Cisco 3725

Subrate and full-rate T3/E3

Medium and large offices

1

Cisco 3745

Subrate and full-rate T3/E3

Medium, large, and regional offices

2


Note


General information about ISDN voice interfaces is presented in the "Information About ISDN Voice Interfaces" section on page 4 .


How to Configure Clear Channel T3 E3 with Integrated CSU DSU

Configuring Clear-Channel T3

This section contains the following procedures:

Configuring the Card Type and Controller for T3

To configure the card type and controller for T3, perform the following steps.


Note


When the clear-channel T3/E3 network module is used for the first time, the running configuration does not show the T3/E3 controller and its associated serial interface. Use the show version command to learn if the router recognized the T3/E3 card and was able to initialize the card properly. After the card type is configured for the slot, the respective controller and serial interfaces appear in the running configuration. See the Additional References.


  • The autoconfig/setup utility does not support configuring the card type for the T3/E3 network module.
SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    card type t3 slot

    4.    controller t3 slot/port

    5.    framing {c-bit| m23}

    6.    cablelength feet

    7.    clock source {internal| line}

    8.    exit


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode. Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 card type t3 slot


    Example:
    Router(config)# card type t3 1
     

    Configures the card type on the T3 controller for the designated slot.

    Note   

    By default, the T3 controller does not show up in the show running-config output.

     
    Step 4 controller t3 slot/port


    Example:
    Router(config)# controller t3 1
     

    Specifies the T3 controller and enters controller configuration mode for the specified slot/port.

     
    Step 5 framing {c-bit| m23}


    Example:
    Router(config-controller)# framing c-bit
     

    Specifies the T3 framing type. Keywords are as follows:

    • c-bit --C-bit framing
    • m23 --M23 framing
     
    Step 6 cablelength feet


    Example:
    Router(config-controller)# cablelength 250
     

    Specifies the distance from the routers to the network equipment.

     
    Step 7 clock source {internal| line}


    Example:
    Router(config-controller)# clock source line
     

    Selects the clock source. Keywords are as follows:

    • internal --Internal clock source (T3 default)
    • line --Network clock source (E3 default)
     
    Step 8 exit


    Example:
    Router(config-controller)# exit
     

    Exits the current mode.

     

    Configuring DSU Mode and Bandwidth for T3

    To configure DSU mode and bandwidth for T3, perform the following steps.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface serial slot/port

      4.    dsu mode {0 | 1| 2| 3| 4}

      5.    dsu bandwidth kbps

      6.    exit


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Router> enable
       

      Enables privileged EXEC mode. Enter your password if prompted.

       
      Step 2 configure terminal


      Example:
      Router# configure terminal
       

      Enters global configuration mode.

       
      Step 3 interface serial slot/port


      Example:
      Router(config)# interface serial 1/1
       

      Enters interface configuration mode for the specified slot/port.

       
      Step 4 dsu mode {0 | 1| 2| 3| 4}


      Example:
      Router(config-if)# dsu mode 0
       

      Specifies the interoperability mode used by a T3 controller--that is, to what the T3 controller connects. Keywords are as follows:

      • 0 --Another T3 controller or a Digital Link DSU (DL3100) (default)
      • 1 --Kentrox DSU
      • 2 --Larscom DSU
      • 3 --Adtran T3SU 300
      • 4 --Verilink HDM 2182
       
      Step 5 dsu bandwidth kbps


      Example:
      Router(config-if)# dsu bandwidth 44210
       

      Specifies the maximum allowable bandwidth, in kbps. Range: 1 to 44210.

      Note   

      The real (actual) vendor-supported bandwidth range is 75 to 44210 kbps. See Configuring DSU Mode and Bandwidth for T3.

       
      Step 6 exit


      Example:
      Router(config-if)# exit
       

      Exits the current mode.

       

      Configuring Encryption Scrambling for T3

      To configure encryption scrambling for T3, perform the following steps.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface serial slot/port

        4.    scramble

        5.    exit


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables privileged EXEC mode. Enter your password if prompted.

         
        Step 2 configure terminal


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 interface serial slot/port


        Example:
        Router(config)# interface serial 1/1
         

        Enters interface configuration mode for the specified slot/port.

         
        Step 4 scramble


        Example:
        Router(config-if)# scramble
         

        Enables the scrambling of the payload. Default: off.

         
        Step 5 exit


        Example:
        Router(config-if)# exit
         

        Exits the current mode.

         

        Configuring a Bit-Error-Rate Test Pattern for T3

        To configure a bit-error-rate test pattern for T3, perform the following steps.

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    controller t3 slot/port

          4.    bert pattern {2^23 | 2^20 | 2^15 | 1s | 0s | alt-0-1} interval time

          5.    no bert

          6.    exit


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example:
          Router> enable
           

          Enables privileged EXEC mode. Enter your password if prompted.

           
          Step 2 configure terminal


          Example:
          Router# configure terminal
           

          Enters global configuration mode.

           
          Step 3 controller t3 slot/port


          Example:
          Router(config)# controller t3 1/1
           

          Enters controller configuration mode for the specified slot/port.

           
          Step 4 bert pattern {2^23 | 2^20 | 2^15 | 1s | 0s | alt-0-1} interval time


          Example:
          Router(config-controller)# bert pattern 2^20 interval 10000
           

          Configures a bit-error-rate test pattern. Keywords and arguments are as follows:

          • 2^23 --Pseudorandom 0.151 test pattern, 8,388,607 bits long
          • 2^20 --Pseudorandom 0.153 test pattern, 1,048,575 bits long
          • 2^15 --Pseudorandom 0.151 test pattern, 32,768 bits long
          • 1s --Repeating pattern of ones (...111...)
          • 0s --Repeating pattern of zeros (...000...)
          • alt-0-1 --Repeating pattern of alternating zeros and ones (...01010...)
          • interval time --Duration of the BER test, in minutes.
           
          Step 5 no bert


          Example:
          Router(config-controller)# no bert
           

          Disables the BERT test pattern.

           
          Step 6 exit


          Example:
          Router(config-controller)# exit
           

          Exits the current mode.

           

          Configuring Loopback for T3

          To configure loopback for T3, perform the following steps.

          SUMMARY STEPS

            1.    enable

            2.    configure terminal

            3.    controller t3 slot/port

            4.    loopback {local | network {line| p ayload}| remote}

            5.    no loopback

            6.    exit


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 enable


            Example:
            Router> enable
             

            Enables privileged EXEC mode. Enter your password if prompted.

             
            Step 2 configure terminal


            Example:
            Router# configure terminal
             

            Enters global configuration mode.

             
            Step 3 controller t3 slot/port


            Example:
            Router(config)# controller t3 1/1
             

            Enters controller configuration mode for the specified slot/port.

             
            Step 4 loopback {local | network {line| p ayload}| remote}


            Example:
            Router(config-controller)# loopback local
             

            Loops the T3 line toward the line and back toward the router. Keywords are as follows:

            • local-- Loops the data back toward the router and sends an alarm-indication signal (AIS) out toward the network. On a dual port card, it is possible to run channelized on one port and primary rate on the other port.
            • network line | payload} --Sets loopback toward the network before going through the framer (line) or after going through the framer (payload).
            • remote --Sends a far-end alarm control (FEAC) request to the remote end requesting that it enter into a network line loopback. FEAC requests (and therefore remote loopbacks) are possible only when the T3 is configured for C-bit framing. M23 format does not support remote loopbacks.
             
            Step 5 no loopback


            Example:
            Router(config-controller)# no loopback
             

            Removes the loop.

             
            Step 6 exit


            Example:
            Router(config-controller)# exit
             

            Exits the current mode.

             

            Configuring the Maintenance Data Link for T3

            To configure the maintenance date link for T3, perform the following steps.


            Note


            This configuration information is applicable only to C-bit parity T3.


            SUMMARY STEPS

              1.    enable

              2.    configure terminal

              3.    controller t3 slot/port

              4.    mdl {transmit{path| idle-signal | test-signal} | string{eic | lic | fic | unit | pfi | port | generator} string}

              5.    exit


            DETAILED STEPS
               Command or ActionPurpose
              Step 1 enable


              Example:
              Router> enable
               

              Enables privileged EXEC mode. Enter your password if prompted.

               
              Step 2 configure terminal


              Example:
              Router# configure terminal
               

              Enters global configuration mode.

               
              Step 3 controller t3 slot/port


              Example:
              Router(config)# controller t3 1/1
               

              Enters controller configuration mode for the specified slot/port.

               
              Step 4 mdl {transmit{path| idle-signal | test-signal} | string{eic | lic | fic | unit | pfi | port | generator} string}


              Example:
              Router(config-controller)# mdl transmit path
               

              Configures the MDL message. Keywords and arguments are as follows:

              • transmit path-- Enables transmission of the MDL path message.
              • transmit idle-signal-- Enables transmission of the MDL idle signal message.
              • transmit test-signal-- Enables transmission of the MDL test signal message.
              • string eic string -- Equipment identification code (EIC); can be up to 10 characters.
              • string lic string --Location identification code (LIC); can be up to 11 characters.
              • string fic string --Frame identification code (FIC); can be up to 10 characters.
              • string unit string --Unit identification code (UIC); can be up to 6 characters.
              • string pfi string --Facility identification code (PFI) sent in the MDL path message; can be up to 38 characters.
              • string port string --Port number string sent in the MDL idle signal message; can be up to 38 characters.
              • string generator string-- Generator number string sent in the MDL test signal message; can be up to 38 characters.
               
              Step 5 exit


              Example:
              Router(config-controller)# exit
               

              Exits the current mode.

               

              Configuring Clear-Channel E3

              This section contains the following procedures:

              Configuring the Card Type and Controller for E3

              To configure the card type and controller for E3, perform the following steps.


              Note


              The autoconfig/setup utility does not support configuring the card type for the T3/E3 network module.


              SUMMARY STEPS

                1.    enable

                2.    configure terminal

                3.    card type e3 slot

                4.    controller e3 slot/port

                5.    framing {bypass| g751}

                6.    clock source { internal | line }

                7.    exit


              DETAILED STEPS
                 Command or ActionPurpose
                Step 1 enable


                Example:
                Router> enable
                 

                Enables privileged EXEC mode. Enter your password if prompted.

                 
                Step 2 configure terminal


                Example:
                Router# configure terminal
                 

                Enters global configuration mode.

                 
                Step 3 card type e3 slot


                Example:
                Router(config)# card type e3 1
                 

                Configures the card type on the E3 controller for the designated slot.

                Note   

                By default, the E3 controller does not show up in the show running-config output.

                 
                Step 4 controller e3 slot/port


                Example:
                Router(config)# controller e3 1
                 

                Enters controller configuration mode for the specified slot/port.

                 
                Step 5 framing {bypass| g751}


                Example:
                Router(config-controller)# framing bypass
                 

                Specifies the framing type. Keywords are as follows:

                • bypass --G.751 framing is bypassed
                • g751 --G.751 is the E3 framing type (default)
                 
                Step 6 clock source { internal | line }


                Example:
                Router(config-controller)# clock source line
                 

                Selects the clock source. Keywords are as follows:

                • internal --Internal clock source (T3 default)
                • line --Network clock source (E3 default)
                 
                Step 7 exit


                Example:
                Router(config-controller)# exit
                 

                Exits the current mode.

                 

                Configuring DSU Mode and Bandwidth for E3

                To configure DSU mode and bandwidth for E3, perform the following steps.

                SUMMARY STEPS

                  1.    enable

                  2.    configure terminal

                  3.    interface serial slot/port

                  4.    dsu mode {0 | 1}

                  5.    dsu bandwidth kbps

                  6.    exit


                DETAILED STEPS
                   Command or ActionPurpose
                  Step 1 enable


                  Example:
                  Router> enable
                   

                  Enables privileged EXEC mode. Enter your password if prompted.

                   
                  Step 2 configure terminal


                  Example:
                  Router# configure terminal
                   

                  Enters global configuration mode.

                   
                  Step 3 interface serial slot/port


                  Example:
                  Router(config)# interface serial 1/1
                   

                  Enters interface configuration mode for the specified slot/port.

                   
                  Step 4 dsu mode {0 | 1}


                  Example:
                  Router(config-if)# dsu mode 0
                   

                  Specifies the interoperability mode used by an E3 controller--that is, to what the E3 controller connects. Keywords are as follows:

                  • 0-- (default) Another E3 controller or a digital link DSU (DL3100)
                  • 1-- Kentrox DSU
                   
                  Step 5 dsu bandwidth kbps


                  Example:
                  Router(config-if)# dsu bandwidth 34010
                   

                  Specifies the maximum allowable bandwidth, in kbps. Range: 22 to 34010.

                  Note   

                  The real (actual) vendor-supported bandwidth range is 358 to 34010 kbps. See Configuring DSU Mode and Bandwidth for E3.

                   
                  Step 6 exit


                  Example:
                  Router(config-if)# exit
                   

                  Exits the current mode.

                   

                  Configuring Encryption Scrambling for E3

                  To configure encryption scrambling for E3, perform the following steps.

                  SUMMARY STEPS

                    1.    enable

                    2.    configure terminal

                    3.    interface serial slot/port

                    4.    scramble

                    5.    exit


                  DETAILED STEPS
                     Command or ActionPurpose
                    Step 1 enable


                    Example:
                    Router> enable
                     

                    Enables privileged EXEC mode. Enter your password if prompted.

                     
                    Step 2 configure terminal


                    Example:
                    Router# configure terminal
                     

                    Enters global configuration mode.

                     
                    Step 3 interface serial slot/port


                    Example:
                    Router(config)# interface serial 1/1
                     

                    Enters interface configuration mode for the specified slot/port.

                     
                    Step 4 scramble


                    Example:
                    Router(config-if)# scramble
                     

                    Enables the scrambling of the payload. Default: off.

                     
                    Step 5 exit


                    Example:
                    Router(config-if)# exit
                     

                    Exits the current mode.

                     

                    Configuring a Bit-Error-Rate Test Pattern for E3

                    To configure a bit-error-rate test pattern for E3, perform the following steps.

                    SUMMARY STEPS

                      1.    enable

                      2.    configure terminal

                      3.    controller e3 slot/port

                      4.    bert pattern {2^23 | 2^20 | 2^15 | 1s | 0s | alt-0-1} interval time

                      5.    no bert

                      6.    exit


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1 enable


                      Example:
                      Router> enable
                       

                      Enables privileged EXEC mode. Enter your password if prompted.

                       
                      Step 2 configure terminal


                      Example:
                      Router# configure terminal
                       

                      Enters global configuration mode.

                       
                      Step 3 controller e3 slot/port


                      Example:
                      Router(config)# controller e3 1/0
                       

                      Enters controller configuration mode for the specified slot/port.

                       
                      Step 4 bert pattern {2^23 | 2^20 | 2^15 | 1s | 0s | alt-0-1} interval time


                      Example:
                      Router(config-controller)# bert pattern 2^20 interval 1440
                       

                      Enables a bit-error-rate (BER) test pattern on a T1 or E1 line, and sets the length of the test pattern and duration of the test. Keywords and arguments are as follows:

                      • 2^23 --Pseudorandom 0.151 test pattern, 8,388,607 bits long
                      • 2^20 --Pseudorandom 0.153 test pattern, 1,048,575 bits long
                      • 2^15 --Pseudorandom 0.151 test pattern, 32,768 bits long
                      • 1s --Repeating pattern of ones (...111...)
                      • 0s --Repeating pattern of zeros (...000...)
                      • alt-0-1 --Repeating pattern of alternating zeros and ones (...01010...)
                      • interval time --Duration of the BER test, in minutes
                       
                      Step 5 no bert


                      Example:
                      Router(config-controller)# no bert
                       

                      Disables the BER test pattern.

                       
                      Step 6 exit


                      Example:
                      Router(config-controller)# exit
                       

                      Exits the current mode.

                       

                      Configuring Loopback for E3

                      To configure loopback for E3, perform the following steps.

                      SUMMARY STEPS

                        1.    enable

                        2.    configure terminal

                        3.    controller e3 slot/port

                        4.    loopback {local | network {line | payload} }

                        5.    no loopback

                        6.    exit


                      DETAILED STEPS
                         Command or ActionPurpose
                        Step 1 enable


                        Example:
                        Router> enable
                         

                        Enables privileged EXEC mode. Enter your password if prompted.

                         
                        Step 2 configure terminal


                        Example:
                        Router# configure terminal
                         

                        Enters global configuration mode.

                         
                        Step 3 controller e3 slot/port


                        Example:
                        Router(config)# controller e3 1/1
                         

                        Enters controller configuration mode for the specified slot/port.

                         
                        Step 4 loopback {local | network {line | payload} }


                        Example:
                        Router(config-controller)# loopback local
                         

                        Loops the E3 line toward the line and back toward the router. Keywords are as follows:

                        • local-- Loops the data back toward the router and sends an AIS signal out toward the network.
                        • network line payload -- Sets loopback toward the network before going through the framer (line) or after going through the framer (payload).
                         
                        Step 5 no loopback


                        Example:
                        Router(config-controller)# no loopback
                         

                        Removes the loop.

                         
                        Step 6 exit


                        Example:
                        Router(config-controller)# exit
                         

                        Exits the current mode.

                         

                        Configuring the National Bit in the G.751 Frame for E3

                        To configure the national bit in the G.751 frame for E3, perform the following steps.

                        SUMMARY STEPS

                          1.    enable

                          2.    configure terminal

                          3.    controller e3 slot/port

                          4.    national bit { 1 | 0 }

                          5.    exit


                        DETAILED STEPS
                           Command or ActionPurpose
                          Step 1 enable


                          Example:
                          Router> enable
                           

                          Enables privileged EXEC mode. Enter your password if prompted.

                           
                          Step 2 configure terminal


                          Example:
                          Router# configure terminal
                           

                          Enters global configuration mode.

                           
                          Step 3 controller e3 slot/port


                          Example:
                          Router(config)# controller e3 1/1
                           

                          Enters controller configuration mode for the specified slot/port.

                           
                          Step 4 national bit { 1 | 0 }


                          Example:
                          Router(config-controller)# national bit 1
                           

                          Sets the E3 national bit in the G.751 frame used by the E3 controller. Valid values: 0 and 1. Default: 1.

                           
                          Step 5 exit


                          Example:
                          Router(config-controller)# exit
                           

                          Exits the current mode.

                           

                          Verifying Clear-Channel T3 E3

                          To verify clear-channel T3/E3, perform the following steps (listed alphabetically).

                          SUMMARY STEPS

                            1.    show controllers

                            2.    show interfaces serial

                            3.    show isdn status

                            4.    show running-config

                            5.    show version


                          DETAILED STEPS
                            Step 1   show controllers

                            Use this command to display information about the specified port, connector, or interface card number (location of voice module) or slot/port (location of voice network module and VIC).

                            Step 2   show interfaces serial

                            Use this command to display information about a serial interface.

                            Step 3   show isdn status

                            Use this command to display the status of all ISDN interfaces, including active layers, timer information, and switch-type settings.

                            Step 4   show running-config

                            Use this command to display basic router configuration.

                            Step 5   show version

                            Use this command to display whether the router recognized the T3/E3 card and was able to initialize the card properly. Lists the hardware interfaces and controllers present in the router. You should find "1 Subrate T3/E3 port(s)".



                            Example:
                            Router# show version
                            .
                            .
                            .
                            Router uptime is 2 hours, 6 minutes
                            System returned to ROM by power-on
                            System image file is "flash:c3725-i-mz"
                            cisco 3725 (R7000) processor (revision 0.4) with 111616K/19456K bytes of memory.
                            Processor board ID 12345678901
                            R7000 CPU at 240Mhz, Implementation 39, Rev 3.3, 256KB L2 Cache
                            Bridging software.
                            X.25 software, Version 3.0.0
                            Primary Rate ISDN software, Version 1.1
                            2 FastEthernet/IEEE 802.3 interface(s)
                            1 Serial network interface(s)
                            2 Channelized T1/PRI port(s)
                            1 Subrate T3/E3 port(s)
                            DRAM configuration is 64 bits wide with parity disabled.
                            55K bytes of non-volatile configuration memory.
                            15680K bytes of ATA System CompactFlas (Read/Write)
                            Configuration register is 0x0
                            

                            Troubleshooting Tips

                            Set Loopbacks
                            • Use T3/E3 local loopback to ensure that the router and the T3/E3 network module are working properly. The controller clock source should be configured to "internal."
                            • Use T3/E3 network loopback and remote loopback to diagnose problems with cables between the T3/E3 controller and the central switching office at the link level. For this diagnostic setup to work, if the network module is looped toward the network, the network module must be configured with the clock source as "line."
                            Run Bit Error Rate Test
                            • The network module contains onboard BERT circuitry. With this circuitry present, the software can send and detect a programmable pattern that is compliant with CCITT/ITU pseudorandom and repetitive test patterns. BERT allows you to test cables and signal problems in the field.
                            • When a BERT is running, your system expects to receive the same pattern that it is sending. To help ensure this, two common options are available.
                              • Use a loopback somewhere in the link or network.
                              • Configure remote testing equipment to send the same BERT pattern at the same time.

                            Configuration Example for Clear Channel T3 E3 with Integrated CSU DSU

                            This example shows the running configuration of a router whose E3 (slot1/0) interface is configured to use G.751 framing and a network (line, or network, is the E3 default) clock source. Note that the bandwidth of the interface is configured to 34010 kbps.

                            Router# show running-config
                            Building configuration...
                            %AIM slot 0 doesn't exist
                            Current configuration :1509 bytes
                            !
                            version 12.2
                            service timestamps debug uptime
                            service timestamps log uptime
                            no service password-encryption
                            !
                            hostname Router1
                            !
                            card type e3 1
                            no logging console
                            !
                            ip subnet-zero
                            no ip routing
                            !
                            voice call carrier capacity active
                            !
                            mta receive maximum-recipients 0
                            !
                            controller E3 1/0
                             clock source line
                             framing g751
                             linecode <line code>
                             dsu bandwidth 34010
                            !
                            interface Loopback0
                             no ip address
                             no ip route-cache
                             shutdown
                             no keepalive
                            !
                            interface FastEthernet0/0
                             ip address 10.0.145.34 255.255.255.0
                             no ip route-cache
                             no ip mroute-cache
                             duplex auto
                             speed auto
                             no cdp enable
                            !
                            interface Serial0/0
                             no ip address
                             encapsulation ppp
                             no ip route-cache
                             no ip mroute-cache
                             shutdown
                             clockrate 2000000
                             no fair-queue
                            !
                            interface FastEthernet0/1
                             no ip address
                             no ip route-cache
                             no ip mroute-cache
                             shutdown
                             duplex auto
                             speed auto
                             no keepalive
                             no cdp enable
                            !
                            interface Serial0/1
                             no ip address
                             encapsulation ppp
                             no ip route-cache
                             no ip mroute-cache
                             shutdown
                             clockrate 2000000
                            !
                            interface Serial0/2:0
                             ip address 172.27.27.2 255.255.255.0
                             no ip route-cache
                             no keepalive
                            !
                            interface Serial1/0
                             no ip address
                             no ip route-cache
                             no keepalive
                             dsu bandwidth 34010
                            !
                            ip classless
                            no ip http server
                            !
                            ip pim bidir-enable
                            !
                            call rsvp-sync
                            !
                            mgcp profile default
                            !
                            dial-peer cor custom
                            !
                            line con 0
                             exec-timeout 0 0
                            line aux 0
                            line vty 0 4
                             login
                            !
                            end

                            Additional References

                            General ISDN References

                            • "Overview of ISDN Voice Interfaces" --Describes relevant underlying technology; lists related documents, standards, MIBs, and RFCs; and describes how to obtain technical assistance
                            • "Additional References" section --Lists additional ISDN references