Re: [rtcweb] Proposal to break the ICE impasse
Christer Holmberg <christer.holmberg@ericsson.com> Wed, 30 January 2019 14:21 UTC
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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: Eric Rescorla <ekr@rtfm.com>, Roman Shpount <roman@telurix.com>
CC: RTCWeb IETF <rtcweb@ietf.org>
Thread-Topic: [rtcweb] Proposal to break the ICE impasse
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Date: Wed, 30 Jan 2019 14:21:29 +0000
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Subject: Re: [rtcweb] Proposal to break the ICE impasse
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Hi, >>> I understand your point. But still I don't understand the purpose of the new draft (set TCP/DTLS/etc in proto line if there are just TCP candidates in the offer). >> >> The purpose is standard compliance. If nominated candidate is UDP, proto line should be UDP. If nominated candidate is TCP, proto line should be TCP. >> If you do not care about the c= and m= line, put the dummy values and UDP there, but this breaks legacy interop by causing ICE mismatch. >> >> This is two separate statements that don't necessarily follow form each other >> >>1. This is a matter of standards compliance. >>2. It breaks legacy interop > >I agree on point (1). I'm still waiting for someone to demonstrate point (2) There are networks where nodes (not always SBCs) use the c/m- information to control network resources (e.g., radio bandwidth). Whether UDP vs TCP will have a major impact I don't know, but the point is that the c/m- information IS used. Whether the WG has agreed that the c/m- information is "meaningless" in the JSEP API I don't know, but it for sure is not "meaningless" on the wire. Regards, Christer Putting UDP proto and address from TCP candidate breaks legacy interop as well, but it is typically localized to provider managed server, so it is possible to patch around this either in JS client or on the server to treat WebRTC clients differently. Alternatively, WebRTC clients can add a couple lines of code and become compliant with the RFC they decided to implement and remove the need for patching. Of course, if browser follow the ICE spec and set the selected candidate in the c/m lines, they must also indicate whether that is over UDP or TCP. The problem here is what such a proto line is intended to mean when there is ICE candidates of UDP and TCP. But ok, let's assume that browser do update c/m lines in the trigger with the selected candidate, and they JUST change the proto line to TCP/DTLS if there are just TCP candidates. Now thing about this scenario: 1) Client initial offer with UDP and TCP candidates. 2) Server answers with both UDP and TCP candidates. 3.1) UDP is selected. Re-offer is created with just UDP candidates (as per spec). 3.2) or TCP is selected. Re-offer is created with just TCP candidates (as per specs). In both 3.1 and 3.2 the "monitoring Node" doesn't need to inspect the proto line. It can just check the protocol (UDP or TCP) of *any* candidate in the offer to know whether UDP or TCP was selected. Am I wrong? You are correct. Checking c= and m= line is simply to avoid checking and parsing ICE candidates. If monitoring client would handle ICE candidates, then the monitoring client would still need to figure out which candidate is default to record client media IP.. Keeping c= and m= line in sync with default candidate on the client seemed to cause the least amount of problems which is why it was left in ice-sip-sdp. Regards, _____________ Roman Shpount _______________________________________________ rtcweb mailing list mailto:rtcweb@ietf.org https://www.ietf.org/mailman/listinfo/rtcweb
- [rtcweb] Proposal to break the ICE impasse Adam Roach
- Re: [rtcweb] Proposal to break the ICE impasse Ted Hardie
- Re: [rtcweb] Proposal to break the ICE impasse Adam Roach
- Re: [rtcweb] Proposal to break the ICE impasse Adam Roach
- Re: [rtcweb] Proposal to break the ICE impasse Suhas Nandakumar
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Justin Uberti
- Re: [rtcweb] Proposal to break the ICE impasse Christer Holmberg
- Re: [rtcweb] Proposal to break the ICE impasse Justin Uberti
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Ted Hardie
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Adam Roach
- Re: [rtcweb] Proposal to break the ICE impasse Ted Hardie
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Adam Roach
- Re: [rtcweb] Proposal to break the ICE impasse Ted Hardie
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Nils Ohlmeier
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Iñaki Baz Castillo
- Re: [rtcweb] Proposal to break the ICE impasse Christer Holmberg
- Re: [rtcweb] Proposal to break the ICE impasse Christer Holmberg
- Re: [rtcweb] Proposal to break the ICE impasse Roman Shpount
- Re: [rtcweb] Proposal to break the ICE impasse Eric Rescorla
- Re: [rtcweb] Proposal to break the ICE impasse Christer Holmberg