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author | Mark Spencer <markster@digium.com> | 1999-12-25 00:13:34 +0000 |
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committer | Mark Spencer <markster@digium.com> | 1999-12-25 00:13:34 +0000 |
commit | 388961dc3533bb4dcb30196271f3af03c7495f2c (patch) | |
tree | d592e83463b5a67701c322c69cd365f2e3d48938 | |
parent | 24e967b70a5509d28b40b3d04ea0d7ecf4419538 (diff) |
Version 0.1.2 from FTP
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@147 65c4cc65-6c06-0410-ace0-fbb531ad65f3
-rwxr-xr-x | doc/iax.txt | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/doc/iax.txt b/doc/iax.txt new file mode 100755 index 000000000..48bb3e10e --- /dev/null +++ b/doc/iax.txt @@ -0,0 +1,55 @@ +Inter-Asterisk eXchange Protocol +================================ + +Usage: +====== +The format for the dialing string on Asterisk is: +IAX/[user@]peer[:exten[@context]] + +(Note, []'s denote optional fields). The peer is either an IP address +or a peer as specified in the /etc/asterisk/iax.conf file. Exten is +an optional requested extension (otherwise "s" will be used), and +"context" is an optional context to request. The user is an optional +username specified in the peer's iax.conf. If the user is not specified, +the peer will select one. + +Protocol and rationale: +======================= +IAX is a simple, low overhead and low bandwidth VoIP protocol designed to +allow multiple Asterisk PBX's to communicate with one another without +the overhead of more complex protocols like H.323. Payload is sent with +a header overhead of only 4 octets. Control functions (and one payload packet +per minute or so) is sent with a more complex header of 12 octets. + +IAX is slightly stateful. + +IAX contains two kinds of packets: The full header packet type, which +contains much information about the frame, in addition to its contents, +and the mini header type, which is used only for non-reliable voice +packet delivery. + +All packets are immediately transmitted. Packets are received, but not +delivered to the actual channels until a given time quantum has passed, in +order to try to eliminate jitter. + +All full header packets must be ackd (except, obviously for the ACK packets +themselves and not so obviously for hangup packets). The "timestamp" field of +ack packets is not the normal offset, but rather a quote of the timestamp as +included with the original packet that you're acking, and likewise the +seqno field is the seqno of the packet you're acking, not your own seqno, +and you do not increment your own sequence number. ACKing is based on the +sequence number. + +See iax.h for a description of the frame formats. + +IAX internal frames use the AST_FRAME_IAX type. The subclass of these +frames is the IAX control number, as seen in iax.h. The first frame sent +must be an AST_FRAME_IAX with the control AST_IAX_CONTROL_NEW. + +The AST_IAX_CONTROL_NEW establishes a new connection. + +The first frame sent MUST be an AST_CONTROL_NEW to start a connection. + +IAX connnections may require authentication using either simple plaintext +passwords or an md5 challenge/response pair. + |