RTP always uses a random even numbered port, then RTCP will use the next port, which will always be odd numbered. Symmetric RTP only needs two ports, while asymmetric RTP uses four.
http://www.armware.dk/RFC/rfc/rfc4961.html On Fri, Jan 14, 2011 at 12:44 PM, Bruce B <bruceb...@gmail.com> wrote: > I mean part of RTP RFC? > > > On Fri, Jan 14, 2011 at 2:41 PM, Bruce B <bruceb...@gmail.com> wrote: > >> Hi Everyone, >> >> I am just tweaking a pfSense router and learning lots about NAT etc....I >> noticed that each call uses four UDP port for RTP. Here is an example of >> port for a call I made: >> >> 10200 >> 10201 >> 10504 >> 10505 >> >> Seems like they are random in pair. I have a restriction of 10000-11000 in >> my rtp.conf so that makes sense. But why use 4 ports per call? is that part >> of SIP RFC? >> >> Thanks >> > > > -- > _____________________________________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > New to Asterisk? Join us for a live introductory webinar every Thurs: > http://www.asterisk.org/hello > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >
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