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Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP & RSVP Agents

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Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Table Of Contents

Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Finding Feature Information

Contents

Prerequisites for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Restrictions for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Information About Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

RTCP Passthrough for MTP, RSVP, TRP Services

MTP Functionality

TRP Functionality

RSVP Functionality

RTCP Passthrough for IPv6 and Video Calls

RTP/RTCP Port Multiplexing

RTP/RTCP Refactoring

RTCP Socket Bypass

Supported Platforms

How to Display RTP/RTCP Packet Count

Verifying RTP/RTCP Packet Count

Example

Configuration Examples for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Where to Go Next

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Glossary


Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services


Revised: November 11, 2011, OL-20468-01
First Published: November 11, 2011
Last Updated: November 11, 2011

This feature describes Audio Real-time Transport Protocol (RTP) Control Protocol (RTCP) enhancements and Video RTCP support for both IPv4 and IPv6 on Integrated Services Router (ISR) gateways for Resource Reservation Protocol (RSVP), Media Termination Point (MTP), and Trusted Relay Point (TRP) services.

The following are the features added in this module:

RTCP passthrough for MTP, RSVP, and TRP agents

RTCP passthrough for IPv6 and video calls

RTP/RTCP port multiplexing

The following enhancements are aslo added to this module:

RTP/RTCP Refactoring

RTCP Socket Bypass

RTCP provides statistics, feedback, keep alives, and collects metrics. It provides mechanism to convey Quality of Service (QoS) data about participants in an audio or video session.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 "Information About Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services" section.

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

Contents

Prerequisites for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Restrictions for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Information About Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

How to Display RTP/RTCP Packet Count

Configuration Examples for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Where to Go Next

Additional References

Feature Information for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Glossary

Prerequisites for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Cisco Unified Communications Manager (CUCM) Version 9.0

Restrictions for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

CME call-flows are not supported for RTCP passthrough.

RTCP for transcoding call-flows is not supported.

RTCP is not supported for conference calls.

RTP/RTCP port multiplexing is not supported for SIP/H323.

Any CUCM scenario that does not handle media is not supported. This includes the RSVP calls with IPv6.

IPv6 for RSVP agent call-flows is not supported.

Information About Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

RTCP Passthrough for MTP, RSVP, TRP Services

RTCP Passthrough for IPv6 and Video Calls

RTP/RTCP Port Multiplexing

RTP/RTCP Refactoring

RTCP Socket Bypass

Verifying RTP/RTCP Packet Count

Where to Go Next

Related Documents

Standards

MIBs

RFCs

Technical Assistance

RTCP Passthrough for MTP, RSVP, TRP Services

RTCP passthrough will be supported for SWMTP, TRP, and RSVP call flows. HWMTP in passthrough mode (codec passthrough) will be supported for RTCP passthrough.

MTP Functionality

Media Termination Point (MTP) is a media device controlled by CUCM/CUCME using Skinny Client Control Protocol (SCCP), and provides services such as transcoding, adhoc conference, and software MTP to CallManager. It bridges RTP streams between two or more endpoints, and allows setup and teardown of the connections independently by CallManager.

TRP Functionality

A Trusted Relay Point (TRP) is a software function that runs on Cisco network devices and is dynamically inserted in the call flow by CallManager when requested. The function is similar to an MTP, but a new name is used to distinguish the way it is being utilized that will extend the behavior beyond the MTP.

The following are the main functions of the TRP agent:

UC Trusted QoS Enforcement

UC Trusted VLAN Traversal

UC Trusted Firewall Traversal

RSVP Functionality

The RSVP agent enables CUCM to provide resource reservation for voice and video media to ensure QoS and call admission control (CAC). CUCM controls the RSVP agent through SCCP. This signaling is independent of the signaling protocol used for the call so SCCP, SIP, H.323, and MGCP calls can all use the RSVP agent.

There would be no extra bandwidth support for the RTCP channel that is enabled because of RTCP passthrough. RTCP traffic is very minimal (5% of RTP traffic) and is generally not counted for the bandwidth calculation.

RTCP Passthrough for IPv6 and Video Calls

RTCP passthrough support will be added for video calls for both IPv4 and IPv6. Support is also extended to IPv6 call flows involving MTP and TRP agents. However, IPv6 for RSVP agent call flows is not supported.

RTP/RTCP Port Multiplexing

An RTP session comprises data packets (RTP) and periodic control packets (RTCP) as described in RFC3550. This RFC does not specify any mechanism for multiplexing the RTP and RTCP packets for the RTP session, and this is deferred to the underlying transport protocol. This was done to keep the implementation simple and efficient and to avoid privacy issues in a multicast session. At the transport layer, the multiplexing was carried out using separate ports (UDP) for RTP and RTCP packets.

One drawback in using separate UDP ports for the RTP/RTCP is that it requires opening of multiple pinholes (for NAT and firewall), and requires complex signaling. RFC5761 proposes a mechanism to multiplex the RTP/RTCP by using the RTCP packet type field occupying the same position as combination of the RTP marker (M) bit (bit 8) and the payload type (PT) field (bits 9 to 15).

Because RTCP packet types 200 to 207 are supported, this means there would be a direct conflict with RTP payload type 72 to 79 with the marker bit set to 1.

RTP/RTCP Refactoring

VOIP RTP functionality will be restructured and broken down in to different modules. This will remove duplicated functionalities and improve compile-time and run-time performance. Restructuring also helps merge the port management functionality.

RTCP Socket Bypass

Processing the RTCP packets in the fast path or process path eliminates the need for a socket which helps improve processing performance and save system resource. It minimizes processing overhead because the packet is already received at the fast path or process path.

Supported Platforms

This feature has been tested on the following platforms:

1861

2901

2911

2921

2951

3925

3925E

3945

3945E

How to Display RTP/RTCP Packet Count

The show voip rtp connections [detail] command is modified to display the RTP and RTCP packet counts per VOIP RTP stream.

Verifying RTP/RTCP Packet Count

Verifying RTP/RTCP Packet Count

To display the RTP and RTCP packet counts per VOIP RTP stream, perform the following steps:

SUMMARY STEPS

DETAILED STEPS

SUMMARY STEPS

1. enable

2. show voip rtp connections [detail]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

show voip rtp connections [detail]

Example:

Router# show voip rtp connections detail

Displays the RTP/RTCP packet counts.

Example

The following example displays the RTP and RTCP packet counts per VOIP RTP stream:

Router> enable
Router# show voip rtp connection detail
VoIP RTP active connections :
No. CallId     dstCallId  LocalRTP RmtRTP     LocalIP RemoteIP                               
1     282        284        18100    16474    1.4.153.2                              
1.4.153.3                              
 callId 282 (dir=2): called= calling= redirect= loopback=NO RTP(tx:386/rx:14011) 
RTCP(tx:44/rx:196)
 peer callId 284: called= calling= redirect=
   1 context 11B xmitFunc 611046D0
2     283        284        17074    18540    1.4.153.2                              
1.4.153.1                              
 callId 283 (dir=2): called= calling= redirect= loopback=NO RTP(tx:14011/rx:386) 
RTCP(tx:196/rx:44)
 peer callId 284: called= calling= redirect=

Configuration Examples for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

There are no new configuration commands required to enable the RTCP passthrough.

Where to Go Next

Related configurations are done in the CUCM 9.0 Release. For the updated CUCM documentation, see http://www.cisco.com/en/US/products/sw/voicesw/ps556/prod_maintenance_guides_list.html. For more information about the show voip rtp connections command, see http://www.cisco.com/en/US/docs/ios/ipv6/command/reference/ipv6_16.html#wp2683095.

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases


Standards

Standard
Title

No new or modified standards are supported and support for existing standards has not been modified.


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.


RFCs

RFC
Title

RFC 3550

RTP: A Transport Protocol for Real-Time Applications

RFC 4585

Extended RTP Profile for Real-time Transport Control


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 Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 1 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.


Table 1 Feature Information for Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services 

Feature Name
Releases
Feature Information

Audio and Video RTCP Passthrough on ISR Gateways for MTP, TRP, and RSVP Agent Services

15.2(2)T

This feature adds call flows involving MTP, RSVP, or TRP agents support for RTCP.

The following command was modified:

show voip rtp connections


Glossary

CUCM—Cisco Unified Call Manager

MTP—Media Termination Point

NAT—Network Address Translation

RSVP—Resource Reservation Protocol

SCCP—Skinny Call Control Protocol

TRP—Trusted Relay Point