XEP-0176: Jingle ICE-UDP Transport Method

Abstract:This specification defines a Jingle transport method that results in sending media data using raw datagram associations via the User Datagram Protocol (UDP). This transport method is negotiated via the Interactive Connectivity Establishment (ICE) methodology, which provides robust NAT traversal for media traffic.
Authors:Joe Beda, Scott Ludwig, Peter Saint-Andre, Joe Hildebrand, Sean Egan, Robert McQueen
Copyright:© 1999 - 2012 XMPP Standards Foundation. SEE LEGAL NOTICES.
Status:Draft
Type:Standards Track
Version:1.0
Last Updated:2009-06-10

NOTICE: The protocol defined herein is a Draft Standard of the XMPP Standards Foundation. Implementations are encouraged and the protocol is appropriate for deployment in production systems, but some changes to the protocol are possible before it becomes a Final Standard.

Table of Contents


1. Introduction
2. Glossary
3. Requirements
4. Jingle Conformance
5. Protocol Description
    5.1. Overall Flow
    5.2. Session Initiation
    5.3. Syntax
    5.4. Response
    5.5. Candidate Negotiation
    5.6. Connectivity Checks
    5.7. Acceptance of Successful Candidate
    5.8. Negotiating a New Candidate
    5.9. ICE Restarts
6. Fallback to Raw UDP
7. Determining Support
    7.1. ICE Support
    7.2. SDP Offer / Answer Support
8. Implementation Notes
9. Deployment Notes
10. Security Considerations
    10.1. Sharing IP Addresses
    10.2. Encryption of Media
11. IANA Considerations
12. XMPP Registrar Considerations
    12.1. Protocol Namespaces
    12.2. Protocol Versioning
    12.3. Service Discovery Features
    12.4. Jingle Transport Methods
13. XML Schema
14. Acknowledgements

Appendices
    A: Document Information
    B: Author Information
    C: Legal Notices
    D: Relation to XMPP
    E: Discussion Venue
    F: Requirements Conformance
    G: Notes
    H: Revision History

1. Introduction

Jingle [1] defines a framework for negotiating and managing out-of-band data sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor application formats, leaving that up to separate specifications.

The current document defines a transport method for establishing and managing data exchanges between XMPP entities over the User Datagram Protocol (see RFC 768 [2]), using the ICE methodology developed within the IETF and specified in RFC 5245 [3] (hereafter referred to as ICE-CORE). Use of this "ice-udp" method results in a datagram transport suitable for media applications where some packet loss is tolerable (e.g., audio and video).

Note: ICE-CORE has been approved for publication as an RFC but has not yet been published as an RFC. While every effort has been made to keep this document synchronized with ICE-CORE, the interested reader is referred to ICE-CORE for a detailed description of the ICE methodology.

The process for ICE negotiation is largely the same in Jingle as it is in ICE. There are several differences:

2. Glossary

The reader is referred to ICE-CORE for a description of various terms used in the context of ICE. Those terms are not reproduced here.

3. Requirements

The Jingle transport method defined herein is designed to meet the following requirements:

  1. Make it possible to establish and manage out-of-band connections between two XMPP entities, even if they are behind Network Address Translators (NATs) or firewalls.
  2. Enable use of UDP as the transport protocol.
  3. Make it relatively easy to implement support in standard Jabber/XMPP clients.
  4. Where communication with non-XMPP entities is needed, push as much complexity as possible onto server-side gateways between the XMPP network and the non-XMPP network.

4. Jingle Conformance

In accordance with Section 10 of XEP-0166, this document specifies the following information related to the Jingle ice-udp transport method:

  1. The transport negotiation process is defined in the Protocol Description section of this document.

  2. The semantics of the <transport/> element are defined in the ICE Negotiation section of this document.

  3. Successful negotiation of the ice-udp method results in use of a datagram transport that is suitable for applications where some packet loss is tolerable, such as audio and video.

  4. If multiple components are to be communicated by the application type that uses the transport, the transport shall support those components and assign identifiers for them as described in the specification that defines the application type.

5. Protocol Description

5.1 Overall Flow

The overall protocol flow for negotiation of the Jingle ICE-UDP Transport Method is as follows (note: many of these events happen simultaneously, not in sequence).

INITIATOR                              RESPONDER
    |                                      |
    |  Jingle session-initiate stanza      |
    |  (with zero or more candidates)      |
    |------------------------------------->|
    |  Jingle ack (XMPP IQ-result)         |
    |<-------------------------------------|
    |  Jingle session-accept stanza        |
    |  (with one or more candidates)       |
    |<-------------------------------------|
    |  Jingle ack (XMPP IQ-result)         |
    |------------------------------------->|
    |  multiple STUN Binding Requests      |
    |<====================================>|
    |  multiple STUN Binding Results       |
    |<====================================>|
    |<=========MEDIA NOW FLOWS============>|
    |  optional Jingle transport-info      |
    |  stanzas (one candidate per stanaza) |
    |<------------------------------------>|
    |                                      |

Note: The examples in this document follow the scenario described in Section 17 of ICE-CORE, except that we substitute the Shakespearean characters "Romeo" and "Juliet" for the generic entities "L" and "R".

5.2 Session Initiation

In order for the initiator in a Jingle exchange to start the negotiation, it sends a Jingle "session-initiate" stanza that includes at least one content type, as described in XEP-0166. If the initiator wishes to negotiate the ice-udp transport method for an application format, it MUST include a <transport/> child element qualified by the 'urn:xmpp:jingle:transports:ice-udp:1' namespace (see Namespace Versioning regarding the possibility of incrementing the version number). This element SHOULD in turn contain one <candidate/> element for each of the initiator's higher-priority transport candidates as determined in accordance with the ICE methodology, but MAY instead be empty (with each candidate to be sent as the payload of a transport-info message).

Example 1. Initiation

<iq from='romeo@montague.lit/orchard'
    id='ixt174g9'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='0' name='PCMU' />
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

5.3 Syntax

The <transport/> element's 'pwd' and 'ufrag' attributes MUST be included whenever sending one or more candidates to the other party, e.g. in a session-initiate, session-accept, transport-info, content-add, or transport-replace message. The values for these attributes are separately generated for both the initiator and the responder, in accordance with ICE-CORE and as shown in the examples. The attributes of the <transport/> element are as follows.

Table 1: Transport Attributes

Name Description SDP Syntax Example
pwd A Password as defined in ICE-CORE. a=ice-pwd line asd88fgpdd777uzjYhagZg
ufrag A User Fragment as defined in ICE-CORE. a=ice-ufrag line 8hhy

The attributes of the <candidate/> element are as follows.

Table 2: Candidate Attributes

Name Description SDP Syntax Example
component A Component ID as defined in ICE-CORE. Component ID value in a=candidate line 1
foundation A Foundation as defined in ICE-CORE. Foundation value in a=candidate line 1
generation An index, starting at 0, that enables the parties to keep track of updates to the candidate throughout the life of the session. For details, see the ICE Restarts section of this document. N/A 0
id A unique identifier for the candidate. N/A el0747fg11
ip The Internet Protocol (IP) address for the candidate transport mechanism; this can be either an IPv4 address or an IPv6 address. IP Address value in a=candidate line 192.0.2.3
network An index, starting at 0, referencing which network this candidate is on for a given peer (used for diagnostic purposes if the calling hardware has more than one Network Interface Card). N/A 0
port The port at the candidate IP address. Port value in a=candidate line 45664
priority A Priority as defined in ICE-CORE. [6] Priority value in a=candidate line 2130706431
protocol The protocol to be used. The only value defined by this specification is "udp". [7] Transport protocol field in a=candidate line udp
rel-addr A related address as defined in ICE-CORE. raddr value in a=candidate line 10.0.1.1
rel-port A related port as defined in ICE-CORE. rport value in a=candidate line 8998
type A Candidate Type as defined in ICE-CORE. The allowable values are "host" for host candidates, "prflx" for peer reflexive candidates, "relay" for relayed candidates, and "srflx" for server reflexive candidates. Typ field in a=candidate line srflx

5.4 Response

As described in XEP-0166, to acknowledge receipt of the session initiation request, the responder immediately returns an IQ-result.

Example 2. Responder acknowledges receipt of session-initiate request

<iq from='juliet@capulet.lit/balcony'
    id='ixt174g9'
    to='romeo@montague.lit/orchard'
    type='result'/>

Depending on the application type, a user agent controlled by a human user might need to wait for the user to affirm a desire to proceed with the session before continuing. When the user agent has received such affirmation (or if the user agent can automatically proceed for any reason, e.g. because no human intervention is expected or because a human user has configured the user agent to automatically accept sessions with a given entity), it returns a Jingle session-accept message. This message MUST contain a <transport/> element qualified by the 'urn:xmpp:jingle:transports:ice-udp:1' namespace, which SHOULD in turn contain one <candidate/> element for each ICE-UDP candidate generated by or known to the responder, but MAY instead be empty (with each candidate to be sent as the payload of a transport-info message).

Note: See the Security Considerations section of this document regarding the exposure of IP addresses by the responder's client.

Example 3. Responder accepts the session request

<iq from='juliet@capulet.lit/balcony'
    id='rw782g55'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='YH75Fviy6338Vbrhrlp8Yh'
                 ufrag='9uB6'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

5.5 Candidate Negotiation

The initiator and responder negotiate connectivity over ICE by exchanging XML-formatted transport candidates for the channel. This negotiation proceeds immediately in order to maximize the possibility that connectivity can be established (and therefore media can be exchanged) as quickly as possible. In order to expedite session establishment, the initiator SHOULD include transport candidates in its session-initiate message but MAY also send additional transport candidates as soon as it learns of them, even before receiving acknowledgement of the session-initiate message (i.e., the initiator MUST consider the session to be live as soon as it sends the session-initiate message). [8]

The first step in negotiating connectivity is for each party to send transport candidates to the other party. [10] These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of ICE-CORE (typically by communicating with a standalone STUN server in order to discover the client's public IP address and port) and prioritized by following the procedure specified in Section 4.1.2 of ICE-CORE.

Each candidate shall be sent as a <candidate/> child of a <transport/> element qualified by the 'urn:xmpp:jingle:transports:ice-udp:1' namespace. The <transport/> element is sent via a Jingle message of type session-initiate, session-accept, or transport-info.

Either party MAY include multiple <candidate/> elements in one <transport/> element, especially in the session-initiate and session-accept messages sent at the beginning of the session negotiation. Including multiple candidates in the session-initiate and session-accept messages can help to ensure interoperability with entities that implement the SDP offer/answer model described in RFC 3264; in particular, an entity SHOULD include multiple candidates in its session-initiate or session-accept message if the other party advertises support for the "urn:ietf:rfc:3264" service discovery feature as described in the SDP Offer / Answer Support section of this document. However, including one candidate per subsequent transport-info message typically results in a faster negotiation because the candidates most likely to succeed are sent first (in the session-info and session-accept messages) and it is not necessary to gather all candidates before beginning to send any candidates; furthermore, because certain candidates can be more "expensive" in terms of bandwidth or processing power, either party might not want to advertise the existence of such candidates unless it is necessary to do so after other candidates have failed.

If the party that receives a candidate in a Jingle message can successfully process a given candidate or set of candidates, it returns an IQ-result (if not, for example because the candidate data is improperly formatted, it returns an IQ-error). At this point, the receiving entity is only indicating receipt of the candidate or set of candidates, not telling the other party that the candidate will be used.

The initiator can keep sending candidates (without stopping to receive an acknowledgement of receipt from the responder for each candidate) until it has exhausted its supply of possible or desirable transport candidates. The responder can also keep sending potential candidates, which the initiator will acknowledge.

5.6 Connectivity Checks

As the initiator and responder receive candidates, they probe the candidates for connectivity. In performing these connectivity checks, each party SHOULD follow the procedure specified in Section 7 of ICE-CORE. The following business rules apply:

  1. Each party sends a STUN Binding Request (see RFC 5389 [11]) from each local candidate it generated to each remote candidate it received.
  2. In accordance with ICE-CORE, the STUN Binding Requests MUST include the PRIORITY attribute (computed according to Section 7.1.1.1. of ICE-CORE).
  3. For the purposes of the Jingle ICE-UDP Transport Method, both parties are full ICE implementations and therefore the controlling role MUST be assumed by the initiator and the controlled role MUST be assumed by the responder.
  4. The STUN Binding Requests generated by the initiator MAY include the USE-CANDIDATE attribute to indicate that the initiator wishes to cease checks for this component.
  5. The STUN Binding Requests generated by the initiator MUST include the ICE-CONTROLLING attribute.
  6. The STUN Binding Requests generated by the responder MUST include the ICE-CONTROLLED attribute.
  7. The parties MUST use STUN short term credentials to authenticate requests and perform message integrity checks. As in ICE-CORE, the username in the STUN Binding Request is of the form "ufrag-of-peer:ufrag-of-sender" and the password is the value of the 'pwd' attribute provided by the peer. [12]

When it receives a STUN Binding Request, each party MUST return a STUN Binding Response, which indicates either an error case or the success case. As described in Section 7.1.2.2 of ICE-CORE, a connectivity check succeeds if all of the following are true:

  1. The STUN transaction generated a success response.
  2. The source IP address and port of the response equals the destination IP address and port to which the Binding Request was sent.
  3. The destination IP address and port of the response match the source IP address and port from which the Binding Request was sent.

For the candidates exchanged in the previous section, the connectivity checks would be as follows (this diagram mirrors the example in ICE-CORE).

INITIATOR                  NAT                  RESPONDER
    |                       |                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.1:3478   |
    |                       | to   10.0.1.1:8998    |
    |                       |   (dropped)           |
    |                       |  x====================|
    | STUN Binding Request  |                       |
    | from 10.0.1.1:8998    |                       |
    | to   192.0.2.1:3478   |                       |
    | USE-CANDIDATE         |                       |
    |======================>|                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.3:45664  |
    |                       | to   192.0.2.1:3478   |
    |                       | USE-CANDIDATE         |
    |                       |======================>|
    |                       | STUN Binding Response |
    |                       | from 192.0.2.1:3478   |
    |                       | to   192.0.2.3:45664  |
    |                       |<======================|
    | STUN Binding Response |                       |
    | from 192.0.2.1:3478   |                       |
    | to   10.0.1.1:8998    |                       |
    | map  192.0.2.3:45664  |                       |
    |<======================|                       |
    |                       |                       |
    |<==Media Now Can Flow==|                       |
    |                       |                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.1:3478   |
    |                       | to   192.0.2.3:45664  |
    |                       |<======================|
    | STUN Binding Request  |                       |
    | from 192.0.2.1:3478   |                       |
    | to   10.0.1.1:8998    |                       |
    |<======================|                       |
    | STUN Binding Response |                       |
    | from 10.0.1.1:8998    |                       |
    | to   192.0.2.1:3478   |                       |
    | map  192.0.2.1:3478   |                       |
    |======================>|                       |
    |                       | STUN Binding Response |
    |                       | from 192.0.2.3:45664  |
    |                       | to   192.0.2.1:3478   |
    |                       | map  192.0.2.1:3478   |
    |                       |======================>|
    |                       |                       |
    |                       |==Media Now Can Flow==>|
    |                       |                       |

Note: Here the initiator (controlling agent) is using "aggressive nomination" as described in Section 8.1.1.2 of ICE-CORE and therefore includes the USE-CANDIDATE attribute in the STUN Binding Requests it sends.

5.7 Acceptance of Successful Candidate

If, based on STUN connectivity checks, the parties determine that they will be able to exchange media between a given pair of local candidates and remote candidates (i.e., the pair is "nominated" and ICE processing is "completed"), they can then begin using that candidate pair to exchange media.

Once the parties have connectivity and therefore the initiator has completed ICE as explained in ICE-CORE, the initiator MAY communicate the in-use candidate pair in the signalling channel by sending a transport-info message that contains a <remote-candidate/> element (this maps to the SDP "remote-candidates" attribute as described in Section B.6 of ICE-CORE, i.e., remote candidates are "the actual candidates at R that were selected by the offerer", of which there will be only one at this stage of the ICE-UDP negotiation).

Example 4. Initiator communicates in-use candidate

<iq from='romeo@montague.lit/orchard'
    id='pd81b49s'
    to='juliet@capulet.lit/balcony'
    type='set'>
 <jingle xmlns='urn:xmpp:jingle:1'
         action='transport-info'
         initiator='romeo@montague.lit/orchard'
         sid='a73sjjvkla37jfea'>
   <content creator='initiator' name='this-is-the-audio-content'>
     <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                pwd='asd88fgpdd777uzjYhagZg'
                ufrag='8hhy'>
       <remote-candidate component='1'
                         ip='10.0.1.2'
                         port='9001'/>
     </transport>
   </content>
 </jingle>
</iq>

(In accordance with Jingle core, the responder will also acknowledge the transport-info message.)

In the unlikely event that one of the parties determines that it cannot establish connectivity even after sending and checking lower-priority candidates, it SHOULD terminate the session as described in XEP-0166.

5.8 Negotiating a New Candidate

Even after media has begun to flow, either party MAY continue to send additional candidates to the other party (e.g., because the user agent has become aware of a new media proxy or network interface card). Such candidates are shared by sending a transport-info message.

Example 5. Initiator sends a subsequent candidate

<iq from='romeo@montague.lit/orchard'
    id='uh3g1f48'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='m3110wc4nd'
                   ip='2001:db8::9:1'
                   network='0'
                   port='9001'
                   priority='21149780477'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>

The receiving party MUST acknowledge receipt of the candidate.

Example 6. Recipient acknowledges receipt

<iq from='juliet@capulet.lit/balcony'
    id='uh3g1f48'
    to='romeo@montague.lit/orchard'
    type='result'/>

The parties would check the newly-offered candidate for connectivity, as described previously. If the parties determine that media can flow over the candidate, they MAY then use the new candidate in subsequent communications.

5.9 ICE Restarts

At any time, either party MAY restart the process of ICE negotiation by sending a candidate with a 'generation' value that is greater than the previous generation of candidates; when it does so, it MUST generate new values for the 'pwd' and 'ufrag' attributes, consistent with the definition of an ICE restart in Section 9.1.1.1 of ICE-CORE. As explained in ICE-CORE, typically the ICE negotiation would be restarted to change the media target (e.g., an IP address change for one of the parties) and certain third-party-call-control scenarios.

Example 7. Initiator restarts ICE negotiation

<iq from='romeo@montague.lit/orchard'
    id='kl23fs71'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-info'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='bv71hdn38hgb39hf6xlk33'
                 ufrag='g7qs'>
        <candidate component='1'
                   foundation='1'
                   generation='1'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45665'
                   priority='1694498815'
                   protocol='udp'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

The recipient then acknowledges receipt.

Example 8. Recipient acknowledges transport-info

<iq from='juliet@capulet.lit/balcony'
    id='kl23fs71'
    to='romeo@montague.lit/orchard'
    type='result'/>

The parties would then exchange new candidates to renegotiate connectivity and would check the new candidates for connectivity, as described previously. If the parties determine that media can flow over one of the new candidates, they can then use the successful candidate in subsequent communications. However, while ICE is being renegotiated the parties can continue to send media with the existing candidate-in-use.

6. Fallback to Raw UDP

It can happen that the responder does not support ICE, in which case it can be necessary to fall back to use of the Jingle Raw UDP Transport Method [13]. One typical scenario is communication between an ICE-aware Jingle endpoint and a non-ICE-aware SIP endpoint through a Jingle-to-SIP gateway, as follows:

  1. The Jingle endpoint sends a session-initiate request to the SIP endpoint, specifying a transport method of ICE-UDP.
  2. Based on capabilities information, the gateway knows that the SIP endpoint does not support ICE, so it enables the endpoints to use its media relay. It does this by:

The session flow is as follows.

Romeo                    Gateway                    Juliet
  |                         |                         |
  |   session-initiate      |                         |
  |   (audio definition)    |                         |
  |------------------------>|                         |
  |   ack                   |                         |
  |<------------------------|                         |
  |   transport-replace     |                         |
  |   (Raw UDP)             |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|                         |
  |   transport-accept      |                         |
  |------------------------>|                         |
  |   ack                   |                         |
  |<------------------------|   SIP INVITE            |
  |                         |------------------------>|
  |                         |   200 OK                |
  |                         |<------------------------|
  |   session-accept        |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|                         |
  |                    MEDIA SESSION                  |
  |<=================================================>|
  |                         |   SIP BYE               |
  |                         |<------------------------|
  |   session-terminate     |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|   ack                   |
  |                         |------------------------>|
  |                         |                         |

The protocol flow is as follows, showing only the stanzas sent between Romeo and the gateway (acting on Juliet's behalf).

Example 9. Initiator sends session-initiate

<iq from='romeo@montague.lit/orchard'
    id='p01hf63x'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice-udp:1'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='1'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='2'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>

Example 10. Responder acknowledges session-initiate

<iq from='juliet@capulet.lit/balcony'
    id='p01hf63x'
    to='romeo@montague.lit/orchard'
    type='result'/>

Immediately the gateway sends a transport-replace message to Romeo, specifying a transport of Raw UDP with a candidate whose IP address and port identify a media relay at the gateway.

Example 11. Gateway sends transport-replace on behalf of responder

<iq from='juliet@capulet.lit/balcony'
    id='hy2gd714'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-replace'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice1'>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'>
        <candidate generation='0'
                   id='a9j3mnbtu1'
                   ip='10.1.1.104'
                   port='13540'/>
      </transport>
    </content>
  </jingle>
</iq>

Romeo then acknowledges the transport-replace message and immediately also sends a transport-accept.

Example 12. Initiator acknowledges transport-replace

<iq from='romeo@montague.lit/orchard'
    id='hy2gd714'
    to='juliet@capulet.lit/balcony'
    type='result'/>

Example 13. Initiator accepts new transport

<iq from='romeo@montague.lit/orchard'
    id='rb391gs5'
    to='juliet@capulet.lit/balcony'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-accept'
          initiator='romeo@montague.lit/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='responder' name='voice2'>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'>
        <candidate generation='0'
                   id='a9j3mnbtu1'
                   ip='10.1.1.104'
                   port='13540'/>
      </transport>
    </content>
  </jingle>
</iq>

The gateway then acknowledges the acceptance on behalf of Juliet.

Example 14. Gateway acknowledges transport-accept

<iq from='juliet@capulet.lit/balcony'
    id='rb391gs5'
    to='romeo@montague.lit/orchard'
    type='result'/>

The responder then sends a session-accept through the gateway.

Example 15. Responder sends session-accept

<iq from='juliet@capulet.lit/balcony'
    id='ijf61d43'
    to='romeo@montague.lit/orchard'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.lit/orchard'
          responder='juliet@capulet.lit/balcony'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'/>
    </content>
  </jingle>
</iq>

Example 16. Initiator acknowledges session-accept

<iq from='romeo@montague.lit/orchard'
    id='ijf61d43'
    to='juliet@capulet.lit/balcony'
    type='result'/>

The endpoints now begin to exchange session media, and can continue the session as long as desired.

7. Determining Support

7.1 ICE Support

To advertise its support for the Jingle ICE-UDP Transport Method, when replying to Service Discovery [14] information requests an entity MUST return URNs for any version of this protocol that the entity supports -- e.g., "urn:xmpp:jingle:transports:ice-udp:1" for this version and "urn:xmpp:jingle:transports:ice-udp:0" for the previous version (see Namespace Versioning regarding the possibility of incrementing the version number).

Example 17. Service discovery information request

<iq from='romeo@montague.lit/orchard'
    id='cv5x41g9'
    to='juliet@capulet.lit/balcony'
    type='get'>
  <query xmlns='jabber.org/protocol/disco#info'/>
</iq>

Related searches:
transport jingle candidate session initiator
gipoco.com is neither affiliated with the authors of this page nor responsible for its contents. This is a safe-cache copy of the original web site.