IP Addressing: NAT Configuration Guide, Cisco IOS Release 15M&T
NAT Optimized SIP Media Path Without SDP
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Contents

NAT Optimized SIP Media Path Without SDP

The NAT Optimized SIP Media Path Without SDP feature provides the ability to optimize the media path taken by a SIP VoIP session when NAT is used. NAT forces the VoIP traffic to take at least one extra hop in the network, which usually results in several additional hops being added to the path between two IP hosts.

The Message Digest 5 (MD5) algorithm is supported.

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.

Information About the NAT Optimized SIP Media Path Without SDP Feature

Benefits of NAT Optimized SIP Media Path Without SDP

  • The media path can be shortened, decreasing voice delay.
  • More control of voice policy is possible because the media path is closer to the customer domain and not deep within the service provider cloud.
  • Processes all packets sent through the NAT-enabled router, even those without the Session Description Protocol (SDP).

NAT Optimized SIP Media Path Without SDP Feature Design

Cisco IOS NAT will add the relevant translation information per SIP session within the SIP protocol messages. The SIP Application Layer Gateway support within Cisco IOS NAT will extract this translation information from the SIP packets and create NAT table entries.

The “piggybacking” of NAT translation information within the SIP call flows, the design of how users interact with the application when they talk to it, will allow the media path of a SIP VoIP session between two calling parties to take the optimized routing path between each other.

How to Configure NAT Optimized SIP Media Path Without SDP

Configuring a NAT Optimized SIP Media Path Without SDP Messages Including MD5 Authentication

Perform this task to configure messages with a NAT optimized SIP Media path including MD5 authentication.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ip nat piggyback-support sip-alg all-messages router router-id [md5-authentication md5-authentication-key]


DETAILED STEPS
      Command or Action Purpose
    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 ip nat piggyback-support sip-alg all-messages router router-id [md5-authentication md5-authentication-key]


    Example:
    Router(config)# ip nat piggyback-support sip-alg all-messages router 100 md5-authentication md5-key
     

    Enables messages with a NAT optimized SIP Media path including MD5 authentication.

     

    Configuring a NAT Optimized SIP Media Path Without SDP Messages

    Perform this task to configure SDP messages with a NAT optimized SIP Media path without MD5 authentication.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ip nat piggyback-support sip-alg all-messages router router-id


    DETAILED STEPS
        Command or Action Purpose
      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 ip nat piggyback-support sip-alg all-messages router router-id


      Example:
      Router(config)# ip nat piggyback-support sip-alg all-messages router 100 
       

      Enables messages with a NAT optimized SIP Media path without MD5 authentication.

       

      Configuration Examples for NAT Optimized SIP Media Path Without SDP

      Configuring a NAT Optimized SIP Media Path Without SDP Including MD5 Authentication Example

      The following example shows how to configure a NAT optimized SIP media path without SDP including MD5 authentication:

      ip nat piggyback-support sip-alg all-messages router 100 md5-authentication md5-key

      Configuring a NAT Optimized SIP Media Path Without SDP or MD5 Authentication Example

      The following example shows how to configure a NAT optimized SIP media path without SDP or MD5 authentication:

      ip nat piggyback-support sip-alg all-messages router 100 

      Additional References

      Related Documents

      Related Topic

      Document Title

      Cisco IOS commands

      Cisco IOS Master Commands List, All Releases

      NAT commands: complete command syntax, command mode command history, defaults, usage guidelines, and examples

      Cisco IOS IP Addressing Services Command Reference

      Application-level gateways

      Using Application Level Gateways with NAT module

      IP access list sequence numbering

      IP Access List Sequence Numbering document

      NAT-on-a-Stick technology note

      Network Address Translation on a Stick technology note

      NAT maintenance

      Monitoring and Maintaining NAT module

      RADIUS attributes overview

      RADIUS Attributes Overview and RADIUS IETF Attributes module

      Using HSRP and stateful NAT for high availability

      Configuring NAT for High Availability module

      Using NAT with MPLS VPNs

      Integrating NAT with MPLS VPNs module

      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 NAT Optimized SIP Media Path Without SDP

      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 NAT Optimized SIP Media Path Without SDP

      Feature Name

      Releases

      Feature Information

      NAT Optimized SIP Media Path Without SDP

      12.4(2)T

      The NAT Optimized SIP Media Path Without SDP feature provides the ability to optimize the media path taken by a SIP VoIP session when NAT is used. NAT forces the VoIP traffic to take at least one extra hop in the network, which usually results in several additional hops being added to the path between two IP hosts.