Access Circuit Redundancy Support for IMA

The Access Circuit Redundancy Support (ACR) for Inverse Multiplexing over ATM (IMA) feature provides a converged IP or Multiprotocol Label Switching (MPLS) access network for its mobile users that use Radio Access Network (RAN) aggregation.

Inverse Multiplexing over ATM (IMA) breaks up the ATM cell stream and distributes the cells over the multiple physical links of an IMA group and then recombines the cells into a single stream at the other end of the connection. In IP RAN 3G networks, ATM cells received on the access side are transported using Layer 2 Transport over an IP or MPLS cloud using MPLS pseudowires (PWs). SONET-APS is used to provide redundancy at the access side that connects the Base Transceiver Station (BTS) and the Circuit Emulation over Packet (CEoP) card in the aggregation router. The convergence time upon failure in this framework is in seconds. ACR provides ACR for SONET-based clients in a Single Router Automatic Protect Switching (SR APS) environment that ensures data traffic downtime of less than 500 milliseconds in case of switchover.

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 ACR Support for IMA

The Access Circuit Redundancy Support for Inverse Multiplexing over ATM feature is supported only on Cisco 7600 routers with Session Initiation Protocol (SIP) 400 line cards and Black Russian (BR) Shared Point Adapters (SPA) (SPA-1CHOC3-CE-ATM).

Restrictions for ACR Support for IMA

  • ACR configuration is an extension of APS and works only with an APS configuration.

  • ACR support is available only for SR APS.

  • There is no provision for migration from the existing physical interface-based configuration, because the entire configuration is on a virtual interface.

  • The maximum number of ACR groups is restricted to the maximum number of SONET controllers or BR SPAs supported on a Cisco 7600 router.

  • There are only 11 slots of SIP 400 (2 for rendezvous point (RP)) available.

  • The absence of dedicated primary and secondary line cards results in port-level redundancy. Each port has to be identified as a primary or secondary.

  • ACR can be configured only after all the previous configurations are removed from the physical interface.

  • Once a member controller of an ACR group is removed during the online insertion and removal (OIR) process, and replaced with another controller, it cannot be reinserted into the ACR group.

Information About ACR Support for IMA

The aggregation of multiple low-speed links (T1/E1) into one or more IMA groups provides IMA support. The ATM IMA interface appears as one logical ATM interface.

How to Configure ACR Support for IMA

Configuring ACR

Support for ACR has been provided using the aps command on the SONET controller. Perform the following steps to configure ACR:

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    controller SONET slot / p-adapter / port

    4.    aps group acr acr-group-number

    5.    aps working channel

    6.    exit

    7.    controller SONET slot / p-adapter / port

    8.    aps group acr acr-group-number

    9.    aps protect circuit-number loopback ip-address

    10.    end


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 SONET slot / p-adapter / port


    Example:
    Router(config)# controller SONET 4/1/0
     

    Selects and configures a SONET controller and enters controller configuration mode.

     
    Step 4 aps group acr acr-group-number


    Example:
    Router(config-controller)# aps group acr 1
     

    Configures the APS group for a SONET controller and enables the ACR functionality on top of an APS.

    • The acr-group-number range is from 0 to 255.

     
    Step 5 aps working channel


    Example:
    Router(config-controller)# aps working 1
     

    Configures a Packet over SONET (POS) interface as a working interface.

     
    Step 6 exit


    Example:
    Router(config-controller)# exit
     

    Exits controller configuration mode and returns to global configuration mode.

     
    Step 7 controller SONET slot / p-adapter / port


    Example:
    Router(config)# controller SONET 4/1/0
     

    Selects and configures a SONET controller and enters controller configuration mode.

     
    Step 8 aps group acr acr-group-number


    Example:
    Router(config-controller)# aps group acr 1
     

    Configures the APS group for a SONET controller and enables the ACR functionality on top of an APS.

    • The acr-group-number range is from 0 to 255.

     
    Step 9 aps protect circuit-number loopback ip-address


    Example:
    Router(config-controller)# aps protect 1 loopback 10.7.7.7
     

    Enables a POS interface as a protect interface.

     
    Step 10 end


    Example:
    Router(config-controller)# end
     

    Exits controller configuration mode and returns to privileged EXEC mode.

     

    Configuring IMA Groups on a Virtual Controller

    To configure the IMA group on a virtual controller, use the following commands:

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    controller SONET-ACR slot / p-adapter / port

      4.    framing sonet

      5.    sts-1 id-number

      6.    mode mode-name

      7.    vtg number interface interface-number ima-group group-number

      8.    exit

      9.    exit

      10.    interface IMA-ACR group-number /ima ima-group-id

      11.    pvc vpi / vci l2transport

      12.    xconnect peer-id vc-id encapsulation mpls

      13.    end


    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 SONET-ACR slot / p-adapter / port


      Example:
      Router(config)# controller SONET-ACR 4/1/0
       

      Selects and configures a SONET ACR controller and enters controller configuration mode.

       
      Step 4 framing sonet


      Example:
      Router(config-controller)# framing sonet
       

      Specifies SONET framing.

       
      Step 5 sts-1 id-number


      Example:
      Router(config-controller)# sts-1 1
       

      Specifies the Synchronous Transport Signal (STS) identifier and enters STS controller configuration mode.

       
      Step 6 mode mode-name


      Example:
      Router(config-ctrlr-sts1)# mode vt-15
       

      Configures the STS-1 mode of operation.

       
      Step 7 vtg number interface interface-number ima-group group-number


      Example:
      Router(config-ctrlr-sts1)# vtg 1 t1 1 ima-group 1
       

      Configures the interface to run in IMA mode and assigns the interface to an IMA group.

       
      Step 8 exit


      Example:
      Router(config-ctrlr-sts1)# exit
       

      Exits STS controller configuration mode and returns to controller configuration mode.

       
      Step 9 exit


      Example:
      Router(config-controller)# exit
       

      Exits controller configuration mode and returns to global configuration mode.

       
      Step 10 interface IMA-ACR group-number /ima ima-group-id


      Example:
      Router(config)# interface IMA-ACR1/ima0
       

      Configures an IMA ACR group and enters interface configuration mode.

      • The IMA-ACR keyword specifies the virtual IMA interface.

      • The group-number argument specifies the ACR group ID.

      • The ima-group-idspecifies the IMA group.

       
      Step 11 pvc vpi / vci l2transport


      Example:
      Router(config-if)# pvc 1/100 l2transport
       

      Assigns a name to an ATM permanent virtual circuit (PVC), specifies the encapsulation type on an ATM PVC, and enters interface ATM L2 transport PVC configuration mode.

       
      Step 12 xconnect peer-id vc-id encapsulation mpls


      Example:
      Router(config-if-atm-l2trans-pvc)# xconnect 10.1.1.1 1234 encapsulation mpls
       

      Binds an attachment circuit to a pseudowire, configures an Any Transport over MPLS (AToM) static pseudowire and enters interface ATM L2 transport PVC xconnect configuration mode.

       
      Step 13 end


      Example:
      Router(config-if-atm-l2trans-pvc-xconn)# end
       

      Exits interface ATM L2 transport PVC xconnect mode and returns to privileged EXEC mode.

       

      Configuring an ATM PVC on an ACR Interface or Group

      To create a virtual ATM ACR group or an IMA ACR interface and configure an ATM PVC, use the following commands:

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface IMA-ACR group-number /ima ima-group-id

        4.    pvc vpi / vci l2transport

        5.    xconnect peer-id vc-id encapsulation mpls

        6.    end


      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 IMA-ACR group-number /ima ima-group-id


        Example:
        Router(config)# interface IMA-ACR 1/ima 0
         

        Configures an IMA ACR group and enters interface configuration mode.

        • The IMA-ACR keyword specifies the virtual IMA interface.

        • The group-number argument specifies the ACR group ID.

        • The ima-group-idspecifies the IMA group.

         
        Step 4 pvc vpi / vci l2transport


        Example:
        Router(config-if)# pvc 1/100 l2transport
         

        Assigns a name to an ATM permanent virtual circuit (PVC), specifies the encapsulation type on an ATM PVC, and enters interface ATM L2 transport PVC configuration mode.

         
        Step 5 xconnect peer-id vc-id encapsulation mpls


        Example:
        Router(config-if-atm-l2trans-pvc)# xconnect 10.1.1.1 1234 encapsulation mpls
         

        Binds an attachment circuit to a pseudowire, configures an AToM static pseudowire and enters interface ATM L2 transport PVC xconnect configuration mode.

         
        Step 6 end


        Example:
        Router(config-if-atm-l2trans-pvc-xconn)# end
         

        Exits interface ATM L2 transport PVC xconnect mode and returns to privileged EXEC mode.

         

        Configuring an ATM PVP on an IMA ACR Interface or Group

        To create a virtual ATM ACR group or an IMA ACR interface and configure an ATM PVP, use the following commands:

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    interface IMA_ACR group-number /ima ima-group-id

          4.    atm pvp vpi l2transport

          5.    xconnect peer-id vc-id encapsulation mpls

          6.    end


        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 IMA_ACR group-number /ima ima-group-id


          Example:
          Router(config)# interface IMA-ACR 1/ima 0
           

          Configures an IMA ACR group and enters interface configuration mode.

          • The IMA-ACR keyword specifies the virtual IMA interface.

          • The group-number argument specifies the ACR group ID.

          • The ima-group-idspecifies the IMA group.

           
          Step 4 atm pvp vpi l2transport


          Example:
          Router(config-if)# atm pvp 100 l2transport
           

          Assigns a name to an ATM permanent virtual path (PVP), specifies the encapsulation type on an ATM PVP, and enters interface ATM L2 transport PVP configuration mode.

           
          Step 5 xconnect peer-id vc-id encapsulation mpls


          Example:
          Router(config-if-atm-l2trans-pvp)# xconnect 10.1.1.1 1234 encapsulation mpls
           

          Binds an attachment circuit to a pseudowire, configures an AToM static pseudowire and enters interface ATM L2 transport PVP xconnect configuration mode.

           
          Step 6 end


          Example:
          Router(config-if-atm-l2trans-pvp-xconn)# end
           

          Exits interface ATM L2 transport PVP xconnect mode and returns to privileged EXEC mode.

           

          Configuration Examples for ACR Support for IMA

          Example Configuring ACR and IMA Groups

          The following example shows how ACR and IMA groups are configured:

          Working ACR Member

          controller SONET 4/1/0
framing sonet
clock source line
!
sts-1 1
mode vt-15
!
sts-1 2
mode vt-15
!
sts-1 3
mode vt-15
aps group acr 1
aps working 1

          Protect ACR Member

          controller SONET 4/3/0
framing sonet
clock source line
!
sts-1 1
mode vt-15
!
sts-1 2
mode vt-15
!
sts-1 3
mode vt-15
aps group acr 1
aps protect 1 10.2.2.2
controller SONET-ACR 1
framing sonet
!
sts-1 1
mode vt-15
!
sts-1 2
mode vt-15
!
sts-1 3
mode vt-15
vtg 1 t1 1 ima-group 0
interface IMA-ACR 1/ima 0
no ip address
pvc 2/34 l2transport
xconnect 10.3.3.3 1234 encapsulation mpls
!
end

          Example Configuring an IMA ACR Interface on an ATM PVP

          The following example shows how an IMA ACR interface on ATM PVP is configured:

          interface ATM 1/0/0
 aps group acr 1
 aps working 1
!
interface ATM 1/0/1
aps group acr 1
aps protect 1 10.2.2.2
!
interface Loopback 1
 ip address 10.1.1.1 255.255.255.0
interface ATM-ACR 1
no ip address
atm pvp 10 l2transport
    xconnect 10.2.2.2 1234 encapsulation mpls

          Example ACR show Command Output

          The show acr groupcommand lists the status of all active ACR groups:

          Router# show acr group
ACR Group Working I/f Protect I/f Currently Active Status
--------------------------------------------------------------------------
1 SONET 4/1/0 SONET 4/3/0 SONET 4/1/0
The show acr group
 
acr-group-number
 
command lists the status of a specific ACR group:
Router# show acr group 1
ACR Group Working I/f Protect I/f Currently Active Status
--------------------------------------------------------------------------
1 SONET 4/1/0 SONET 4/3/0 SONET 4/1/0

          The show acr group acr-group-number detail command lists the status and details of a specific ACR group:

          Router# show acr group 1 detail ima
ACR Group Working I/f Protect I/f Currently Active Status
--------------------------------------------------------------------------
IM1/ima0 ATM4/1/ima0 ATM4/3/ima0 ATM4/1/ima0
ATM PVC Detail
VPI VCI State on Working State on Protect
2 34 Provision Success Unknown
Router#
The show controllers SONET-ACR
 
slot
/
p-adapter
/
port
 
command lists the details of the active controllers:
Router# show controllers sonet 4/1/0
SONET 4/1/0 is up.
Hardware is SPA-1CHOC3-CE-ATM
Applique type is Channelized Sonet/SDH
Clock Source is Line
Medium info:
  Type: Sonet, Line Coding: NRZ, 
 SECTION:
  LOS = 0          LOF = 0                           BIP(B1) = 13
SONET/SDH Section Tables
  INTERVAL       CV    ES   SES  SEFS
  06:13-06:28     0     0     0     0
  05:58-06:13     0     0     0     0
  05:43-05:58     0     0     0     0
  .
  .
  .
  23:43-23:58     0     0     0     0
  23:28-23:43     0     0     0     0
  06:13-06:28     0     0     0     0
Total of Data in Current and Previous Intervals
  06:13-06:28     0     0     0     0
LINE:
  AIS = 0          RDI = 0          REI = 351390     BIP(B2) = 23        
Active Defects: None
Active Alarms: None
Alarm reporting enabled for: SLOS SLOF 
Defect reporting enabled for: SF B1-TCA B2-TCA 
BER thresholds:  SF = 10e-3  SD = 10e-6
TCA thresholds:  B1 = 10e-6  B2 = 10e-6
SONET/SDH Line Tables
  INTERVAL       CV    ES   SES   UAS
  06:13-06:28     0     0     0     0
  05:58-06:13     0     0     0     0
  05:43-05:58     0     0     0     0
  .
  .
  .
  Total of Data in Current and Previous Intervals
  06:13-06:28     0     0     0     0
High Order Path:
PATH 1:
  AIS = 0          RDI = 1          REI = 2302655982 BIP(B3) = 3659922183
  LOP = 0          PSE = 32         NSE = 0          NEWPTR = 0         
  LOM = 0          PLM = 0          UNEQ = 0         
Active Alarms: None
Active Defects: PRDI B3-TCA 
Alarm/Defect reporting enabled for: PLOP LOM B3-TCA 
TCA threshold:  B3 = 10e-6
Rx: S1S0 = 02, C2 = 02
    K1 = 00,   K2 = 00
    J0 = 01 
Tx: S1S0 = 00, C2 = 02
    K1 = 00,   K2 = 00
    J0 = 01
PATH TRACE BUFFER : STABLE 
  45 32 20 32 2F 33 2F 30 2E 31 00 00 00 00 E6 50     E2 2/3/0.1.....P
  45 32 20 32 2F 33 2F 30 2E 31 00 00 00 00 E6 50     E2 2/3/0.1.....P
  45 32 20 32 2F 33 2F 30 2E 31 00 00 00 00 E6 50     E2 2/3/0.1.....P
  45 32 20 32 2F 33 2F 30 2E 31 00 00 00 00 E6 50     E2 2/3/0.1.....P
  
SONET/SDH Path Tables
.

          The show imacommand lists the details of IMA activation on the active interfaces:

          Router# show ima
ATM4/1/ima0 is up, ACTIVATION COMPLETE
Slot 4 Slot Unit 64 unit 256, CTRL VC 256, Vir -1, VC 4097
IMA Configured BW 1523, Active BW 1523
IMA version 1.1, Frame length 128
Link Test: Disabled
Auto-Restart: Disabled
ImaGroupState: NearEnd = operational, FarEnd = operational
ImaGroupFailureStatus = noFailure
IMA Group Current Configuration:
ImaGroupMinNumTxLinks = 1 ImaGroupMinNumRxLinks = 1
ImaGroupDiffDelayMax = 25 ImaGroupNeTxClkMode = common(ctc)
ImaGroupFrameLength = 128 ImaTestProcStatus = disabled
ImaGroupTestLink = None ImaGroupTestPattern = 0x0
ImaGroupConfLink = 1 ImaGroupActiveLink = 1
IMA Link Information:
ID Link Link State - Ctlr/Chan/Prot Test Status
---- -------------- ------------------------------ ---------------
0 VT1.5 3/1/1 Up Up Up Up disabled
ATM4/3/ima0 is up, ACTIVATION COMPLETE
Slot 4 Slot Unit 192 unit 256, CTRL VC 256, Vir -1, VC 4097
IMA Configured BW 1523, Active BW 1523
IMA version 1.1, Frame length 128
Link Test: Disabled
Auto-Restart: Disabled
ImaGroupState: NearEnd = startUp, FarEnd = groupStateUnknown
ImaGroupFailureStatus = startUpNe
IMA Group Current Configuration:
ImaGroupMinNumTxLinks = 1 ImaGroupMinNumRxLinks = 1
ImaGroupDiffDelayMax = 25 ImaGroupNeTxClkMode = common(ctc)
ImaGroupFrameLength = 128 ImaTestProcStatus = disabled
ImaGroupTestLink = None ImaGroupTestPattern = 0x0
ImaGroupConfLink = 1 ImaGroupActiveLink = 0
IMA Link Information:
ID Link Link State - Ctlr/Chan/Prot Test Status
---- -------------- ------------------------------ ---------------
0 VT1.5 3/1/1 Up Up Up Up disabled
IMA-ACR1/ima0 is up, CONFIG COMPLETE
Slot 14 Slot Unit 1 unit 256, CTRL VC 256, Vir -1, VC 4097
IMA Configured BW 1523, Active BW 1523
IMA version 1.1, Frame length 128
Link Test: Disabled
Auto-Restart: Disabled
ImaGroupState: NearEnd = operational, FarEnd = operational
ImaGroupFailureStatus = noFailure
IMA Group Current Configuration:
ImaGroupMinNumTxLinks = 1 ImaGroupMinNumRxLinks = 1
ImaGroupDiffDelayMax = 25 ImaGroupNeTxClkMode = common(ctc)
ImaGroupFrameLength = 128 ImaTestProcStatus = disabled
ImaGroupTestLink = None ImaGroupTestPattern = 0x0
ImaGroupConfLink = 1 ImaGroupActiveLink = 1
IMA Link Information:
ID Link Link State - Ctlr/Chan/Prot Test Status
---- -------------- ------------------------------ ---------------
0 VT1.5 3/1/1 Up Up Up Up disabled

          The show ima interface interface-name IMA-ACRcommand lists the details of IMA-ACR activation on a specific interface:

          Router# show ima interface IMA-ACR 1/ima 0
IMA-ACR1/ima0 is up, CONFIG COMPLETE
Slot 14 Slot Unit 1 unit 256, CTRL VC 256, Vir -1, VC 4097
IMA Configured BW 1523, Active BW 1523
IMA version 1.1, Frame length 128
Link Test: Disabled
Auto-Restart: Disabled
ImaGroupState: NearEnd = operational, FarEnd = operational
ImaGroupFailureStatus = noFailure
IMA Group Current Configuration:
ImaGroupMinNumTxLinks = 1 ImaGroupMinNumRxLinks = 1
ImaGroupDiffDelayMax = 25 ImaGroupNeTxClkMode = common(ctc)
ImaGroupFrameLength = 128 ImaTestProcStatus = disabled
ImaGroupTestLink = None ImaGroupTestPattern = 0x0
ImaGroupConfLink = 1 ImaGroupActiveLink = 1
IMA Link Information:
ID Link Link State - Ctlr/Chan/Prot Test Status
---- -------------- ------------------------------ ---------------
0 VT1.5 3/1/1 Up Up Up Up disabled

          Additional References for ATM OAM Traffic Reduction

          Related Documents

          Related Topic

          Document Title

          Cisco IOS commands

          Cisco IOS Master Commands List, All Releases

          ATM commands

          Cisco IOS Asynchronous Transfer Mode Command Reference

          MIBs

          MIB

          MIBs Link

          None

          To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

          http:/​/​www.cisco.com/​go/​mibs

          RFCs

          RFC

          Title

          None

          --

          Technical Assistance

          Description

          Link

          The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

          http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

          Feature Information for ACR Support for IMA

          The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

          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.

          Table 1 Feature Information for Access Circuit Redundancy Support for Inverse Multiplexing over ATM

          Feature Name

          Releases

          Feature Information

          Access Circuit Redundancy Support for Inverse Multiplexing over ATM

          15.1(1)S

          The Access Circuit Redundancy Support for IMA over ATM feature provides a converged IP or MPLS access network for its mobile users that use RAN aggregation.