Re: [rtcweb] Data channel comments and questions

Eric Rescorla <> Thu, 29 March 2012 20:48 UTC

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From: Eric Rescorla <>
Date: Thu, 29 Mar 2012 22:48:17 +0200
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Subject: Re: [rtcweb] Data channel comments and questions
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On Thu, Mar 29, 2012 at 10:36 PM,  <> wrote:
> Hi,
> Eric Rescorla [] wrote:
>>> 3. HTTP tunneling: In practice we are going to need HTTP tunneling last-
>>resort option for the data channel as well. If doing so, what will the protocol
>>stack look like? Is it SCTP/DTLS/UDP/HTTP/TLS/TCP? Or can we collapse some
>>of these layers. I think we'd better.
>>I don't think I understand point 3. Why would we need HTTP tunneling?
>>If we can bring
>>up a bidirectional UDP channel, then why would we need to run HTTP over it?
> Ah, sorry for not being clear. I mean a situation where we can't setup the UDP channel, if one endpoint is for instance in a corporate network from where only HTTP or HTTPS is allowed. So presumably we'd have to support some kind of HTTP or TLS encapsulation/tunneling for the data channel as well, from the endpoint to some kind of relay. But how would the end-to-end data channel look like then? I.e. what would be sent over the tunnel?

I had sort of assumed that people would use that HTTP/HTTPS encapsulation only
to a relay which emitted UDP, so that that encapsulation wouldn't be end-to-end
in the general case.