<abstract>This document defines a Jingle transport method that results in using the Inter-Asterisk eXchange protocol (IAX) for the final communication.</abstract>
<remark><p>Synced with last revision of Jingle and Raw UDP transport. Review some descriptions and modify some names like location for candidate</p></remark>
</revision>
<revision>
<version>0.0.3</version>
<date>2006-02-26</date>
<initials>afc</initials>
<remark><p>Modify the initiate proccess, Rome tell to Juliet the transport to use and she answer with the transport information needed to be contacted. Added to transport the remoteTransport an localTransport data.</p></remark>
</revision>
<revision>
<version>0.0.2</version>
<date>2006-02-24</date>
<initials>afc</initials>
<remark><p>Some fixes and take care of Asterisk PBX entity.</p></remark>
<p>&xep0166; defines a framework for negotiating and managing out-of-band multimedia sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor media (session) types, leaving that up to separate specifications. The current document defines a transport method for establishing and managing &iax; sessions between XMPP entities.</p>
<p>IAX is a peer-to-peer media and signaling protocol, where the endpoints maintain state machines. With respect to media, sequencing and timing information is included into IAX frames, without the use of Real-Time Transport Protocol (RTP) for the media. <note>IAX is a binary protocol; this design choice was made for bandwidth efficiency.</note> The IAX protocol handles the signaling and, when the call is accepted by both peers, the media passes between the two hosts. With this approach, IAX doesn't suffer from NAT traversal problems associated with others protocols like SIP or other related protocols.</p>
</section1>
<section1topic='Requirements'anchor='reqs'>
<p>The Jingle transport description defined herein is designed to meet the following requirements:</p>
<ol>
<li>Enable negotiation of parameters necessary for take in contact both IAX peers.</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 order for the initiating entity in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in <cite>XEP-0166</cite>. This stanza MUST include at least one transport method. If the initiating entity wishes to negotiate the IAX transport, it MUST include an empty &TRANSPORT; child element qualified by the 'http://jabber.org/protocol/jingle/transport/iax' namespace.</p>
<p>To accept the IAX transport method, the target entity MUST send a &JINGLE; element with an action of 'transport-accept', specifying the transport method desired.</p>
<p>This &TRANSPORT; element MUST include two &CANDIDATE; element per channel, whose 'ip' and 'port' attributes specify the IP address and port number of the candidate that the initiator has reason to believe will be most likely to succeed for that channel. The two candidates are the local and remote one. NAT type doesn't matter because the IAX protocol by itself addresses the problem of NAT traversal. We differentiate the two candidates with name attribute.</p>
<p>The transport attributes are:</p>
<ol>
<li>Version -- this is the protocol version we want to use by (currently 1 or 2, perhaps other versions in the future). This information is provided as an attribute of the transport.</li>
<li>User -- the user needed to log into the Asterisk PBX. This is OPTIONAL.</li>
<li>Password -- the password needed to log the User into the Asterisk PBX. This is OPTIONAL.</li>
<li>Secure -- describes the encryption method, this is OPTIONAL because at the moment there is one implementation of AES128 in Asterisk but not in the protocol, this could change in the future.</li>
</ol>
<p>User and Password are OPTIONAL and needed in the case we want to call an extension that is behind an Asterisk PBX. The Asterisk PBX has to be properly configured to accept this kind of call.</p>
<p>When we get the answer, it is time to see if the media that we want to start is supported by both peers. If so the IAX session is initialized by the protocol stack.</p>
<p>The candidate attributes are:</p>
<ol>
<li>Name -- the name of the candidate MUST be local, public or vpn.</li>
<li>IP -- the IP where the candidate is located.</li>
<li>Port -- the port where the candidate is listening.</li>
</ol>
<p>To discover this public IP address we need a third party and SHOULD make discovery via &rfc3489;, which will be an address on the outside of the firewall or NAT.</p>
<examplecaption="Target Entity Accepts the IAX Transport Method"><