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.

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 https://cfnng.cisco.com/. An account on Cisco.com is not required.
Table 1. Feature Information for Delayed-Offer to Early-Offer

Feature Name

Releases

Feature Information

Delayed-Offer to Early-Offer

Cisco IOS 12.4(3)

Cisco IOS 12.4(24)T

Cisco IOS 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 .

Delayed-Offer to Early-Offer Support for Video Calls

Cisco IOS 12.4(22)T

The Delayed-Offer to Early-Offer support was extended for video calls. The following command was introduced:

codec-profile

Media Flow- Around with SIP Signaling control on CUBE

Cisco IOS 15.1(3)T

Support for Media Flow-Around for Delayed-Offer to Early-Offer audio calls on CUBE was introduced. No new commands were introduced or modified.

Midcall Renegotiation Support for DO-EO Calls

Cisco IOS 15.4(2)T

Cisco IOS XE 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] .

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


CUBE supports delayed offer to early offer for SIP-to-SIP video calls. CUBE generates an outgoing Early Offer INVITE with the configured codec list, for a incoming Delayed Offer INVITE.

DO-EO video call is supported if both audio and video codecs are configured under a dial peer. codec profile command defines the codec attributes for Video (H263, H264) and Audio (AACLD) codecs. The codec attributes configured under codec-profile is used to generate the a=fmtp attribute line in the Early Offer SDP.

Configuring Delayed Offer to Early Offer

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. Configure conversion of a delayed offer to an early offer:

    • In dial-peer configuration mode

      voice-class sip early-offer forced

    • In global VoIP SIP configuration mode

      early-offer forced
  4. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

Configure conversion of a delayed offer to an early offer:

  • In dial-peer configuration mode

    voice-class sip early-offer forced

  • In global VoIP SIP configuration mode

    early-offer forced

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 4

end

Exits to privileged EXEC mode.

Configuring Delayed Offer to Early Offer for Video Calls

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. codec profile tag profile
  4. dial-peer voice number number voip
  5. codec codec profile
  6. video codec codec profile
  7. voice-class sip early-offer forced
  8. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

codec profile tag profile

Example:


codec profile 1 aacld
codec profile 2 H264

Configures the audio and video codec profiles.

Step 4

dial-peer voice number number voip

Example:

Device(config)# dial-peer voice 1 voip

Enters dial peer configuration mode for the specified VoIP dial peer.

Step 5

codec codec profile

Example:


Device(config-dial-peer)# profile 1 aacld

Audio codec profile is applied on the dial peer.

Step 6

video codec codec profile

Example:


Device(config-dial-peer)# video codec h264 profile 2

Video codec profile is applied on the dial peer.

Step 7

voice-class sip early-offer forced

Example:


Device (config-dial-peer)# voice-class sip early-offer forced

Step 8

end

Exits to privileged EXEC mode.

Configuring Delayed Offer to Early Offer Medial Flow-Around

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. medial flow-around
  4. Configure conversion of a delayed offer to an early offer:

    • In dial-peer configuration mode

      voice-class sip early-offer forced

    • In global VoIP SIP configuration mode

      early-offer forced
  5. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

medial flow-around

Example:

Device(config-voi-serv)# media flow-around

Enables media flow-around.

Step 4

Configure conversion of a delayed offer to an early offer:

  • In dial-peer configuration mode

    voice-class sip early-offer forced

  • In global VoIP SIP configuration mode

    early-offer forced

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 5

end

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).

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.


Note

For EO to EO calls, the Delayed-Offer midcall RE-INVITE is not triggered by the CUBE, if either midcall-signaling block or midcall-signaling passthru media-change command is configured.

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 Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

dial-peer voice id voip

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

Step 4

media 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 5

end

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" section 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

To configure High-Density Transcoding delayed offer to early offer calls in media flow-around mode, perform the following steps:

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. voice service voip
  4. media transcoder high-density
  5. sip
  6. early offer-forced
  7. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

voice service voip

Example:


Device(config)# voice service voip

Enters voice service configuration mode.

Step 4

media transcoder high-density

Example:

Device(config-voi-serv)# media transcoder high-density

Enables media transcoder high-density for transcoding high-density media calls.

Step 5

sip

Example:

Device(config-voi-serv)# sip

Enters SIP configuration mode.

Step 6

early offer-forced

Example:

Device(config-voi-sip)# early offer-forced

Forcefully sends SIP EO invites on the Out-Leg.

Step 7

end

Example:

Device(config-voi-sip)# end

Exits the present configuration mode.