Re: [rtcweb] Multiplexing using the same port number for multiple media descritions

Christer Holmberg <> Wed, 31 August 2011 17:45 UTC

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From: Christer Holmberg <>
To: Harald Alvestrand <>, "" <>
Date: Wed, 31 Aug 2011 19:43:16 +0200
Thread-Topic: [rtcweb] Multiplexing using the same port number for multiple media descritions
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Subject: Re: [rtcweb] Multiplexing using the same port number for multiple media descritions
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Hi Harald,

>>> I think Harald's approach is cleaner, since the fallback does not require a new offer.
>>> What do you see as problematic with Harald's suggestion?
>> I have sent comments on Harald's draft, but my main issues are:
>> 1. Unclear how to remove the m- line which is used for the multiplexed stream.
>> (Maybe Harald has indicated somewhere how it would be done, and in that case I appologise for having >>missed it)
>> 2. Intermediaries that do not understand the extension would still think that there are individual streams, and >>reserve resources etc accordingly.
>Would those intermediaries understand the double usage in your proposal?

The currently existing products and deployments that I am aware of would reserve different local ports for each m- line. They don't care about that fact that identical remote ports are used. So, there would be no multiplexing, but at least things would work - the correct amount of resources etc would be reserved.