Subject: [bfcpbis] FW: Do we want to mandate all protocols supporting ICE and multiple transports to support transport switch on-the-fly before nomination?

From: Christer Holmberg <[email-masked]>
Date: Sat, 19 Nov 2016 09:30:23 +0000

Forwarding to bfcpbis, as this is very much related to BFCP. If you have comments, please bring those to the ICE WG list, so we get everything in one place :)

Regards,

Christer

From: Ice [mailto:[email-masked]] On Behalf Of Christer Holmberg
Sent: 19 November 2016 11:27
To: [email-masked]
Subject: [Ice] Do we want to mandate all protocols supporting ICE and multiple transports to support transport switch on-the-fly before nomination?

Hi,

One potential issue that came to my mind while reading the SDP m- line thread.

Previously, before removal of aggressive nomination, while and endpoint might support both UDP and TCP for a protocol, it didn't have to be able to simultaneously use the protocol with both UDP and TCP, and switching between. Because, until nomination was done, no protocol data was sent. And, once nomination had been done, endpoints used the protocol with the selected transport.

Now, with the allowed-to-send-media-before-nomination rules, protocols basically have to support switch of transport (from UDP to TCP, and vice versa), until the nomination takes place.

Now, even people always say that a good designed protocol should be transport-independent, isn't *mandating* transport switching on-the-fly (before nomination takes place) by all protocols supporting ICE and multiple transports a bad thing to do?

Perhaps the ICE considerations of each protocol (RTP, BFCP etc) should indicate whether transport switching is supported, and whether there are protocol specific procedures associated with that. I guess a protocol could also specify that data shouldn't be sent in the first place before nomination has been done, if there are good reasons for that.

Regards,

Christer