Cisco Unified Border Element (Enterprise) SIP Support Configuration Guide, Cisco IOS XE Release 3S
Delayed-Offer to Early-Offer
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Delayed-Offer to Early-Offer

Delayed-Offer to Early-Offer

The Delayed-Offer to Early-Offer (DO-EO) feature allows CUBE to convert a delayed offer that it receives into an early offer. This feature is supported in the Media Flow-Around mode.

This feature also supports high-density transcoding calls, where transcoding IP addresses and port numbers are exchanged between the sender and receiver. This feature also supports midcall renegotiation of codecs required if an exchange of parameters that is not end-to-end causes an inefficient media flow.

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 Delayed-Offer to Early-Offer

Configure delayed-offer to early-offer in media flow-around mode.

Restrictions for Delayed-Offer to Early-Offer Media Flow-Around

  • CUBE does not support change in IP address or port number in the locally triggered RE-INVITE response.
  • CUBE does not support DE-EO Media Flow-Around for video calls.

Delayed-Offer to Early-Offer in Media Flow-Around Calls

Delayed-Offer to Early-Offer (DO-EO) allows CUBE to convert a delayed offer (DO) into an early offer (EO) in the media flow-around mode.

CUBE sends its local IP address in the initial EO INVITE Session Description Protocol (SDP) message. In the image, this is illustrated by INVITE (SDP1, CUIP1). Later, an additional RE-INVITE is locally generated by CUBE to communicate the SDP message details from the sender. This is illustrated by RE-INVITE (SDP5, IP2) in the below image. The RE-INVITE response is consumed by CUBE and not communicated to the sender.

Figure 1. Delayed Offer to Early Offer in Media Flow-Around Calls



Configuring Delayed Offer to Early Offer

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    Configure conversion of a delayed offer to an early offer:

    • voice-class sip early-offer forced in dial-peer configuration mode
    • early-offer forced in global VoIP configuration mode

    4.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode. Enter your password if prompted.

     
    Step 2configure terminal


    Example:
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3Configure conversion of a delayed offer to an early offer:
    • voice-class sip early-offer forced in dial-peer configuration mode
    • early-offer forced in global VoIP configuration mode


    Example:In dial-peer configuration mode:
    
    Device (config) dial-peer voice 10 voip
    Device (config-dial-peer) voice-class sip early-offer forced 
    Device (config-dial-peer) end
    


    Example:In global VoIP SIP mode:
    
    Device(config)# voice service voip
    Device (config-voi-serv) sip
    Device (config-voi-sip) early-offer forced
    Device (config-voi-sip) end 
    
     
     
    Step 4end
     

    Exits to privileged EXEC mode.

     

    MidCall Renegotiation Support for Delayed-Offer to Early-Offer Calls

    When CUBE converts a delayed offer into an early offer, an incomplete exchange of Format specific parameters (FMTP) occurs during call establishment, resulting in either the noninitiation of media transmission or media transmission in a quality that may not be the best. This is especially a problem in video calls.

    To overcome this situation, midcall renegotiation of capabilities can be configured.

    The early-offer forced renegotiate [always] command is used to configure this in global VoIP configuration mode (config-voi-serv) and the voice-class sip early-offer forced renegotiate command is dial-peer configuration mode (config-dial-peer) and voice-class configuration mode (config-class). Refer to Modes for Configuring Dial Peers to enter these modes and configure this feature.

    Figure 2. MidCall Renegotiation of Capabilities

    The early-offer forced renegotiate command triggers a delayed-offer RE-INVITE if the negotiated codecs are one of the following:

    • aaclld—Audio codec AACLD 90000 bps
    • h263—Video codec H263
    • h263+—Video codec H263+
    • h264—Video codec H264
    • mp4a—Wideband audio codec

    The early-offer forced renegotiate always command always triggers a delayed-offer RE-INVITE. This option can be used to support all other codecs.

    Restrictions for MidCall Renegotiation Support for DO-EO Calls

    • If midcall-signaling block or midcall-signaling passthru media-change commands have been configured, the feature does not work because a midcall RE-INVITE is not triggered by CUBE.
    • if initial call is transcoded , then midcall re-invite is not triggered by CUBE.

    Configuring Mid Call Renegotiation Support for Delayed-Offer to Early-Offer Calls

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    dial-peer voice id voip

      4.    media transcoder high-density

      5.    end


    DETAILED STEPS
       Command or ActionPurpose
      Step 1enable


      Example:
      Device> enable
       

      Enables privileged EXEC mode. Enter your password if prompted.

       
      Step 2configure terminal


      Example:
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3dial-peer voice id voip
       

      Enters dial-peer configuration mode and configures the selected dial peer.

       
      Step 4media transcoder high-density


      Example:
      
      Device (config) dial-peer voice 10 voip
      Device (config-dial-peer) media transcoder high-density 
      Device (config-dial-peer) end
      
       
       
      Step 5end
       

      Exits to privileged EXEC mode.

       

      High-Density Transcoding Calls in Delayed-Offer to Early-Offer

      High-Density Transcoding Calls in the media flow-around DO-to-EO mode is a feature where the transcoding IP address and port number are exchanged between the originating and terminating user agents. For high-density transcoding calls, CUBE is in the media flow-through mode even if media flow-around is configured.

      In the figure below, XIP1 is passed to CUCM1 when a 200 OK is received from SBC1. ACK from CUCM1 triggers new RE-INVITE with transcoding IP address and port number (XIP2) and this RE-INVITE has to be locally handled in CUBE.

      Figure 3. High-Density Transcoding Calls in DO-to-EO



      The media transcoder high-density command is used to configure this feature in dial-peer configuration mode (config-dial-peer). Refer to Modes for Configuring Dial Peers to enter these modes and configure this feature.

      For high-density transcoding calls with a common codec, CUBE should be in Media Flow-Through mode even though media flow-around is configured.

      Figure 4. High-Density Transcoding Calls for Common Codecs in DO-to-EO



      Restrictions for High-Density Transcoding DO-EO Calls

      For high-density transcoding calls with a common codec, CUBE will be in Media Flow-through mode even though Media Flow-Around is configured.

      Configuring High-Density Transcoding

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    Configure mid-call renegotiation support for DO-EO calls:

        • voice-class sip early-offer forced re-negotiate [always] in dial-peer configuration mode
        • early-offer forced re-negotiate [always] in global VoIP configuration mode

        4.    end


      DETAILED STEPS
         Command or ActionPurpose
        Step 1enable


        Example:
        Device> enable
         

        Enables privileged EXEC mode. Enter your password if prompted.

         
        Step 2configure terminal


        Example:
        Device# configure terminal
         

        Enters global configuration mode.

         
        Step 3Configure mid-call renegotiation support for DO-EO calls:
        • voice-class sip early-offer forced re-negotiate [always] in dial-peer configuration mode
        • early-offer forced re-negotiate [always] in global VoIP configuration mode


        Example:In dial-peer configuration mode:
        
        Device (config) dial-peer voice 10 voip
        Device (config-dial-peer) voice-class sip early-offer forced re-negotiate [always] 
        Device (config-dial-peer) end
        


        Example:In global VoIP SIP mode:
        
        Device(config)# voice service voip
        Device (config-voi-serv) sip
        Device (config-voi-sip) early-offer forced re-negotiate [always]
        Device (config-voi-sip) end 
        
         
         
        Step 4end
         

        Exits to privileged EXEC mode.

         

        Feature Information for Delayed-Offer to Early-Offer

        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 Delayed-Offer to Early-Offer

        Feature Name

        Releases

        Feature Information

        Midcall Renegotiation Support for DO-EO Calls

        15.4(2)T

        Cisco IOS XE Release 3.12S

        The Midcall renegotiation of codecs feature configures the midcall renegotiation of codecs, if an exchange of parameters that is not end-to-end causes an inefficient media flow.

        The following commands were modified by this feature: voice class sip early-offer forced renegotiatle [always], early-offer forced renegotiate [always].

        Delayed-Offer to Early-Offer

        12.4(3)

        12.4(24)T

        15.0(1)M

        The Delayed-Offer to Early-Offer feature allows CUBE to convert a delayed offer it receives into an early offer.

        The following commands were introduced by this feature: voice class sip early-offer forced, early-offer forced and media transcoder high-density.