Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

Table Of Contents

Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

Prerequisites

Restrictions

Information About Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

How to Configure the Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

This feature enables the Cisco Unified Border Element (Cisco UBE) platform to pass through end-to-end headers at a global or dial-peer level, that are not processed or understood in a SIP trunk to SIP trunk scenario. The pass through functionality includes all or only a configured list of unsupported or non-mandatory SIP headers, and all unsupported content/MIME types.

Prerequisites

•Configuring the media flow-around command is required for Session Description Protocol (SDP) pass-through. When flow-around is not configured, the flow-through mode of SDP pass-through will be functional.

•When the dial-peer media flow mode is asymmetrically configured, the default behavior is to fallback to SDP pass-through with flow-through.

Cisco Unified Border Element

•Cisco IOS Release 15.0(1)M or a later release must be installed and running on your Cisco Unified Border Element.

Cisco Unified Border Element (Enterprise)

•Cisco IOS XE Release 3.1S or a later release must be installed and running on your Cisco ASR 1000 Series Router.

Restrictions

When SDP pass-through is enabled, some of interworking that the Cisco Unified Border Element currently performs cannot be activated. These features include:

•Delayed Offer to Early Offer Interworking

•Supplementary Services with triggered Invites

•DTMF Interworking scenarios

•Fax Interworking/QoS Negotiation

•Transcoding

Information About Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

The Cisco UBE does not support end-to-end media negotiation between the two endpoints that establish a call session through the Cisco UBE. This is a limitation when the endpoints intend to negotiate codec/payload types that the Cisco UBE does not process, because currently, unsupported payload types will never be negotiated by the Cisco UBE. Unsupported content types include text/plain, image/jpeg and application/resource-lists+xml. To address this problem, SDP is configured to pass through transparently at the Cisco UBE, so that both the remote ends can negotiate media independently of the Cisco UBE.

SDP pass-through is addressed in two modes:

•Flow-through—Cisco UBE plays no role in the media negotiation, it blindly terminates and re-originates the RTP packets irrespective of the content type negotiated by both the ends. This supports address hiding and NAT traversal.

•Flow-around—Cisco UBE neither plays a part in media negotiation, nor does it terminate and re-originate media. Media negotiation and media exchange is completely end-to-end.

How to Configure the Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters

To enable Cisco UBE Unsupported Content Pass-through perform the steps in this section. This section contains the following subsections:

•Configuring Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters at the Global Level

•Configuring Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters at the Dial Peer Level

Configuring Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters at the Global Level

To configure Unsupported Content Pass-through on a Cisco UBE platform at the global level, perform the steps in this section.

SUMMARY STEPS

1. enable

2. configure terminal

3. voice service voip

4. sip

5. pass-thru {content {sdp | unsupp} | headers {unsupp | list tag}}

6. exit

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	voice service voip Example: Router(config)# voice service voip	Enters voice service VoIP configuration mode.
Step 4	sip Example: Router(conf-voi-serv)# sip	Enters SIP configuration mode.
Step 5	pass-thru {content {sdp | unsupp} | headers {unsupp | list tag}} Example: Router(conf-serv-sip)# pass-thru content unsupp	Passes the SDP transparently from in-leg to the out-leg with no media negotiation.
Step 6	exit Example: Router(conf-serv-sip)# exit	Exits the current mode.

Configuring Cisco Unified Border Element Support for Configurable Pass-through of SIP INVITE Parameters at the Dial Peer Level

To configure Unsupported Content Pass-through on a Cisco UBE platform at the dial-peer level, perform the steps in this section.

SUMMARY STEPS

1. enable

2. configure terminal

3. dial-peer voice tag voip

4. voice-class sip pass-thru {content {sdp | unsupp} | headers {unsupp | list tag}} [system]

5. exit

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	dial-peer voice tag voip Example: Router(config)# dial-peer voice 2 voip	Enters dial peer VoIP configuration mode.
Step 4	voice-class sip pass-thru {content {sdp | unsupp} | headers {unsupp | list tag}} [system] Example: Router(config-dial-peer)# voice-class sip pass-thru content sdp	Passes the SDP transparently from in-leg to the out-leg with no media negotiation.
Step 5	exit Example: Router(config-dial-peer)# exit	Exits the current mode.