RTP UDP port negotiation - expected behavior

Wowza Media Server 3 Perpetual Edition 3.6.2.17 build7663

What is the expected behavior of the UDP ports negotiated by RTSP?

We are sending live streams to Wowza from mobile devices via RTSP/UDP and have noticed the server giving out pairs of ports for each SETUP but continuing on to 10000-10001 once it reaches what I thought was the upper limit of 9999.

Should the server cycle back to the beginning of what is in DatagramStartingPort or continue past 9999 as we are observing?

<DatagramStartingPort>6970</DatagramStartingPort>

In our case we changed it to 9992

<DatagramStartingPort>9992</DatagramStartingPort>

Here is the response we got after sending the SETUP:

RTSP/1.0 200 OK
Date: Wed, 23 Oct 2013 12:20:52 PDT
Transport: RTP/AVP/UDP;unicast;client_port=5000-5001;mode=receive;source=0.0.0.0;server_port=10000-10001
Session: 1254165248;timeout=60
Expires: Wed, 23 Oct 2013 12:20:52 PDT
Cseq: 4
Server: Wowza Media Server 3.6.2.17 build7739
Cache-Control: no-cache

We need to understand the behavior in order to open our firewall to the correct range. Currently it’s open from UDP 9992 to 9999 only.

Thanks,

Robert

This issue has been submitted in ticket #70684.

-Tim