From: Kevin P. Fleming Date: Fri, 15 Jan 2010 16:28:38 +0000 (+0000) Subject: Clarify RTP NAT handling a bit. X-Git-Tag: 11.0.0-beta1~3598 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ef8082cd32dd778b703611ca884c0abd7d09821;p=thirdparty%2Fasterisk.git Clarify RTP NAT handling a bit. git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@240328 65c4cc65-6c06-0410-ace0-fbb531ad65f3 --- diff --git a/configs/sip.conf.sample b/configs/sip.conf.sample index c8f732530e..8fb7237178 100644 --- a/configs/sip.conf.sample +++ b/configs/sip.conf.sample @@ -729,8 +729,20 @@ srvlookup=yes ; Enable DNS SRV lookups on outbound calls ; ; nat = no ; Default. Use rport if the remote side says to use it. ; nat = force_rport ; Force rport to always be on. -; nat = yes ; Force rport to always be on and perform symmetric RTP. -; nat = comedia ; Use rport if the remote side says to use it and perform symmetric RTP. +; nat = yes ; Force rport to always be on and perform comedia RTP handling. +; nat = comedia ; Use rport if the remote side says to use it and perform comedia RTP handling. +; +; 'comedia RTP handling' refers to the technique of sending RTP to the port that the +; the other endpoint's RTP arrived from, and means 'connection-oriented media'. This is +; only partially related to RFC 4145 which was referred to as COMEDIA while it was in +; draft form. This method is used to accomodate endpoints that may be located behind +; NAT devices, and as such the port number they tell Asterisk to send RTP packets to +; for their media streams is not actual port number that will be used on the nearer +; side of the NAT. +; +; In addition to these settings, Asterisk *always* uses 'symmetric RTP' mode as defined by +; RFC 4961; Asterisk will always send RTP packets from the same port number it expects +; to receive them on. ; ; The IP address used for media (audio, video, and text) in the SDP can also be overridden by using ; the media_address configuration option. This is only applicable to the general section and