<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.</abstract>
<remark><p>Specified id attribute and added it to the examples; updated namespaces to reflect changes to other Jingle specifications; completed editorial review.</p></remark>
<remark><p>For consistency with XEP-0166, removed profile attribute, changed content-replace to transport-replace, and changed content-accept to transport-accept.</p></remark>
<remark><p>Allowed batching of multiple candidates in a single transport-info action for optional interworking with the SDP offer-answer model, and added urn:ietf:rfc:3264 service discovery feature to advertise such support; updated security considerations regarding sharing of IP addresses.</p></remark>
<remark><p>Removed content-replace action from acceptance flow, since in ICE that information is sent via STUN, not in the signalling channel.</p></remark>
<remark><p>Moved pwd and ufrag attributes from candidate element to transport element since they describe session-level or media-level information.</p></remark>
<remark><p>Modified flow for ICE completion to require content-modify from initiator to responder, thus mapping to sending of revised offer in SIP; added rem-addr and rem-port attributes to map to a=remote-candidates information in SDP; changed raddr and rport attributes to rel-addr and rel-port to prevent confusion with rem-addr and rem-port attributes.</p></remark>
<remark><p>Separately defined ice-tcp and ice-udp transport methods to enable clearer definition of transport methods and reuse by application types; specified Jingle conformance, including definition of ice-udp as datagram and ice-tcp as streaming.</p></remark>
<remark><p>Updated to track ICE-12; corrected service discovery process; completed editorial review; removed mention of DTMF, which is for audio only.</p></remark>
<p>&xep0166; 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.</p>
<p>The current document defines a transport method for establishing and managing data exchanges between XMPP entities over the User Datagram Protocol (see &rfc0768;), using the ICE methodology developed within the IETF and specified in &ice; (hereafter referred to as &icecore;). Use of the <strong>ice-udp</strong> method results in a datagram transport suitable for media applications where some packet loss is tolerable (e.g., audio and video).</p>
<p>Note: &icecore; 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 &icecore;, the interested reader is referred to &icecore; for a detailed description of the ICE methodology.</p>
<li>In Jingle, lists of "preferred" candidates are typically sent in the Jingle session-initiate and session-accept messages, in a way that is consistent with the SDP offer / answer model described in &rfc3264; and the process described in &icecore;. However, it is also possible to send candidates in separate transport-info messages; this enables a part to send higher-priority candidates earlier in the negotiation and lower-priority candidates later in the negotiation, or to continue sending candidates after session setup to adjust to changing network conditions.</li>
<li>Syntax from the Session Description Protocol (see &rfc4566;) is mapped to an XML syntax suitable for sending over the XMPP signalling channel.</li>
<li>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.</li>
<li>Make it relatively easy to implement support in standard Jabber/XMPP clients.</li>
<li>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.</li>
<p>In accordance with Section 10 of <cite>XEP-0166</cite>, this document specifies the following information related to the Jingle ice-udp transport method:</p>
<li><p>The semantics of the &TRANSPORT; element are defined in the <linkurl='#protocol-negotiate'>ICE Negotiation</link> section of this document.</p></li>
<li><p>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.</p></li>
<li><p>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.</p></li>
<p>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).</p>
<p>Note: The examples in this document follow the scenario described in Section 17 of &icecore;, except that we substitute the Shakespearean characters "Romeo" and "Juliet" for the generic entities "L" and "R".</p>
<p>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 <cite>XEP-0166</cite>. 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 &VNOTE;. This element SHOULD in turn contain one &CANDIDATE; element for each of the 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).</p>
<p>The &TRANSPORT; element's 'pwd' and 'ufrag' attributes MUST be included in the session-initiate request, in subsequent content-add and transport-replace actions, and when offering candidates via the transport-info action. The attributes MAY be included in a session-accept action. The values are separately generated for both the initiator and the responder, in accordance with &icecore; and as shown in the examples. The attributes are defined as follows.</p>
<p>The attributes of the <candidate/> element are described in the following table:</p>
<tablecaption='Candidate Attributes'>
<tr>
<th>Name</th>
<th>Description</th>
<th>SDP Syntax</th>
<th>Example</th>
</tr>
<tr>
<td>component</td>
<td>A Component ID as defined in &icecore;.</td>
<td>Component ID value in a=candidate line</td>
<td>1</td>
</tr>
<tr>
<td>foundation</td>
<td>A Foundation as defined in &icecore;.</td>
<td>Foundation value in a=candidate line</td>
<td>1</td>
</tr>
<tr>
<td>generation</td>
<td>An index, starting at 0, that enables the parties to keep track of updates to the candidate throughout the life of the session.</td>
<td>N/A</td>
<td>0</td>
</tr>
<tr>
<td>id</td>
<td>A unique identifier for the candidate.</td>
<td>N/A</td>
<td>el0747fg11</td>
</tr>
<tr>
<td>ip</td>
<td>The Internet Protocol (IP) address for the candidate transport mechanism; this may be either an IPv4 address or an IPv6 address.</td>
<td>IP Address value in a=candidate line</td>
<td>192.0.2.3</td>
</tr>
<tr>
<td>network</td>
<td>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).</td>
<td>N/A</td>
<td>0</td>
</tr>
<tr>
<td>port</td>
<td>The port at the candidate IP address.</td>
<td>Port value in a=candidate line</td>
<td>45664</td>
</tr>
<tr>
<td>priority</td>
<td>A Priority as defined in &icecore;
<note>In accordance with the rules specified in Section 4.1.1 of &icecore;, the priority values shown in the examples within this document have been calculated as follows. The "type preference" for host candidates is stipulated to be "126" and for server reflexive candidates "100". The "local preference" for network 0 is stipulated to be "4096", for network 1 "2048", and for network 2 "1024".</note>
</td>
<td>Priority value in a=candidate line</td>
<td>2130706431</td>
</tr>
<tr>
<td>protocol</td>
<td>The protocol to be used. The only value defined by this specification is "udp".</td>
<td>Transport protocol field in a=candidate line</td>
<td>udp</td>
</tr>
<tr>
<td>rel-addr</td>
<td>A related address as defined in &icecore;.</td>
<td>raddr value in a=candidate line</td>
<td>10.0.1.1</td>
</tr>
<tr>
<td>rel-port</td>
<td>A related port as defined in &icecore;.</td>
<td>rport value in a=candidate line</td>
<td>8998</td>
</tr>
<tr>
<td>rem-addr</td>
<td>A IP address for a remote address as defined in &icecore;.</td>
<td>connection-address value in a=remote-candidates line</td>
<td>192.0.2.1</td>
</tr>
<tr>
<td>rem-port</td>
<td>The port for a remote address as defined in &icecore;.</td>
<td>port value in a=remote-candidates line</td>
<td>3478</td>
</tr>
<tr>
<td>type</td>
<td>A Candidate Type as defined in &icecore;. The allowable values are "host" for host candidates, "prflx" for peer reflexive candidates, "relay" for relayed candidates, and "srflx" for server reflexive candidates.</td>
<p>As described in <cite>XEP-0166</cite>, to acknowledge receipt of the session initiation request, the responder immediately returns an IQ-result.</p>
<p>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 SHOULD also contain a &TRANSPORT; element that in turn contain one &CANDIDATE; element for each of the responder's higher-priority transport candidates, just as for the session-initiate message, but MAY instead be empty (with each candidate to be sent as the payload of a transport-info message).</p>
<p>Note: See the <linkurl='#security'>Security Considerations</link> section of this document regarding the exposure of IP addresses on behalf by the responder's client.</p>
<examplecaption="Responder accepts the session request"><