All things related to multicast

[Laurence Kirchmeier <>]

Merit is streaming a number of unicast and multicast streams from NANOG 47 in Dearborn Mi.

We are sending one high quality unicast quicktime stream back to a QuickTime streaming server at Merit which then reflects out the stream to unicast connected viewers. Also  I have set up a unicast to multicast relay so that one can receive the reflected stream via multicast.

The URLs for these two streams are:

rtsp://quicktime.merit.edu/nanog.sdp

rtsp://quicktime.merit.edu/nanogmult.sdp

The multicast address being used is 233.0.236.30, port 8000

My connundrum is this:

I am sitting on a wireless network in the hotel in Dearborn and when I load "rtsp://quicktime.merit.edu/nanogmult.sdp" in Quicktime Player, I actually get the video stream.  Now I ask myself how is that possible - perhaps the wireless network is allowing multicast traffic.  Our network engineering staff are sceptical that I am actually seeing multicast traffic and somehow I am receiving a unicast stream.

SO the question is - how can one figure out (on a Macintosh or linux box) whether a stream that is being received by the machine is a multicast stream. I know that  "netstat -rn" shows all the active tcp and udp connections.  In that list how might one detect that a stream is a multicast stream.  Is there some other way to figure out if a stream is a multicast stream?

Any comments, ideas would be helpful - am I missing something obvious?

Laurie

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Laurence Kirchmeier

Video Services Manager & Senior Engineer, Networking R&D

Merit Network, Inc.

1000 Oakbrook Drive, Suite 200, Ann Arbor, MI 48104

Tel.  +1 734 527-5741 Fax. +1 734 527-5790

Email:     

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