Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)
"Karl Stahl" <karl.stahl@intertex.se> Wed, 01 May 2013 18:10 UTC
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From: Karl Stahl <karl.stahl@intertex.se>
To: "'Roy, Radhika R CIV USARMY (US)'" <radhika.r.roy.civ@mail.mil>, "'Cullen Jennings (fluffy)'" <fluffy@cisco.com>, 'Harald Alvestrand' <harald@alvestrand.no>
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Date: Wed, 01 May 2013 20:10:06 +0200
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Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)
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Just to clarify: DTLS setup/key exchange goes over the UDP "voice/video channel". /Karl -----Ursprungligt meddelande----- Från: Roy, Radhika R CIV USARMY (US) [mailto:radhika.r.roy.civ@mail.mil] Skickat: den 1 maj 2013 13:47 Till: Karl Stahl; 'Cullen Jennings (fluffy)'; 'Harald Alvestrand' Kopia: rtcweb@ietf.org Ämne: RE: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED) Classification: UNCLASSIFIED Caveats: NONE Folks: I am responding only on a part of this email about retransmissions of audio or video packets. Let us not consider the retransmission of audio or video packets. Let us consider audio or video packets are sent only over UDP. Let MOS/QoS of audio or video are considered in a way that retransmissions do not take place. Then the question comes only about "data" traffic retransmissions. Data traffic can tolerate much higher delays than that of audio or video. Data has only QoS (and no MOS). Let us divide the performance problems in two different parts. In this case, we can have more focused solutions related to (Audio/Video) MOS/QoS or (Data) QoS as explained above. BR/Radhika -----Original Message----- From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf Of Karl Stahl Sent: Wednesday, May 01, 2013 7:12 AM To: 'Cullen Jennings (fluffy)'; 'Harald Alvestrand' Cc: rtcweb@ietf.org Subject: Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb Regarding delays... Today, packets over the Internet reach any point on the earth within 250 ms as Cullen found - There are simply nowhere packet are stored/buffered in any amount to give higher delays (Where would Gbps be stored for a second?). Routers drop packets at congestion, they don't store them (and light takes 140 ms for a turn around the earth, somewhat slower in a fiber). So, the problem with voice/video quality (if overall bandwidth for the RTP/UDP is sufficient and up) is only dropped packets, which "only" happens at congestion points where the pipe gets filled by TCP data (surf, email, file transfer), when TCP end-points regulate down to share the pipe in their hunger for infinite transfer speed. Then both TCP and RTP/UPD packets are dropped as a consequence of intense TCP-flows initiation. (The static situation is ok - no packets are dropped) Second long packet delays must come from retransmission of lost packets. If DTLS, it must be a higher level retransmission, I believe. Questions: 1) Does DTLS take long time to set up in itself in the browser (Aren't self signed certificate generated and exchanged?) while SRTP/DES is less CPU intense with ready certificate over the signaling path (I think)? But is this significant on let's say a 1 GHz smartphone which would be the lowest CPU power to consider? 2) Are packet drops during TLS-setup more likely over the UDP channel between browsers (as for DTLS) than over the signaling channel (for SRTP/DES). And are there more packets that safely need to arrive with DTLS setup? 3) SRTP/DES setup rely on TCP retransmission if packets are lost (correct me if I am wrong), while DTLS must rely on some other higher level retransmission mechanisms. Are there longer timers involved then? I think this may be the real explanation for reports of slow DTLS setup, isn't it? The only cure against dropped UPD packets is IP-level QoS, such as traffic shaping in firewalls/routers (but they need to be aware of traffic type) and diffserv or reservation over the transport network- but that is (currently) not enabled over the Internet, where all traffic is best effort class. /Karl -----Ursprungligt meddelande----- Från: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] För Cullen Jennings (fluffy) Skickat: den 1 maj 2013 07:10 Till: Harald Alvestrand Kopia: rtcweb@ietf.org Ämne: [rtcweb] Network times was SDP Security Descriptions (RFC 4568) and RTCWeb On Apr 29, 2013, at 2:29 AM, Harald Alvestrand <harald@alvestrand.no> wrote: > Would it be possible to get real data on 1) and 2) here, so that we > can stop talking about "slow" and instead talk about "N milliseconds"? > I did try and round up a bunch of data for ping times from India to Singapore as some people were suggesting these were 1500ms. I got measurements from both home DSL and more business class from a range of sources in India. It seems that anywhere one could run video, you can ping any of Singapore, Tokyo, Boston, Palo Alto, and London in less than 250 ms one way. If someone has an actually link that is getting 1500 ms out of India, I'd love to get the info so I can see what I can learn (the buffer bloat folks want to hear about this :-) Classification: UNCLASSIFIED Caveats: NONE
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman (SKYPE)
- [rtcweb] SDP Security Descriptions (RFC 4568) and… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Alan Johnston
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Bernard Aboba
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Bogineni, Kalyani
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ejzak, Richard P (Richard)
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Igor Faynberg
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Mandeep Singh
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Adam Roach
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ejzak, Richard P (Richard)
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Randell Jesup
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Randell Jesup
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Harald Alvestrand
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Harald Alvestrand
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Randell Jesup
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ted Hardie
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Hutton, Andrew
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Xavier Marjou
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Harald Alvestrand
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Matthew Kaufman
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Oscar Ohlsson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Suhas Nandakumar
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Alan Johnston
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Roman Shpount
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… DRUTA, DAN
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Roman Shpount
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Cullen Jennings (fluffy)
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Roman Shpount
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Salvatore Loreto
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Christer Holmberg
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Bernard Aboba
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Markus.Isomaki
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Binod
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Harald Alvestrand
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Emil Ivov
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Christer Holmberg
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ejzak, Richard P (Richard)
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ted Hardie
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Salvatore Loreto
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ejzak, Richard P (Richard)
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Iñaki Baz Castillo
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Eric Rescorla
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Ejzak, Richard P (Richard)
- [rtcweb] Network times … was SDP Security Descrip… Cullen Jennings (fluffy)
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Tim Panton
- Re: [rtcweb] Network times . was SDP Security Des… Roy, Radhika R CIV USARMY (US)
- Re: [rtcweb] Network times . was SDP Security Des… Cullen Jennings (fluffy)
- Re: [rtcweb] Network times . was SDP Security Des… Justin Uberti
- Re: [rtcweb] Network times . was SDP Security Des… Michael Tuexen
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] Network times . was SDP Security Des… Randell Jesup
- Re: [rtcweb] Network times . was SDP Security Des… Randell Jesup
- Re: [rtcweb] Network times . was SDP Security Des… Roy, Radhika R CIV USARMY (US)
- Re: [rtcweb] Network times . was SDP Security Des… Justin Uberti
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Bo Burman
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Olle E. Johansson
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Daniel-Constantin Mierla
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Harald Alvestrand
- Re: [rtcweb] Network times . was SDP Security Des… Eric Rescorla
- Re: [rtcweb] Network times . was SDP Security Des… Daniel-Constantin Mierla
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] Network times . was SDP Security Des… Dan Wing
- Re: [rtcweb] Network times . was SDP Security Des… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Harald Alvestrand
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Bernard Aboba
- Re: [rtcweb] Network times . was SDP Security Des… Justin Uberti
- Re: [rtcweb] Network times . was SDP Security Des… Karl Stahl
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Henry Lum
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Henry Lum
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Henry Lum
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Martin Thomson
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Tim Panton
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Cullen Jennings
- Re: [rtcweb] SDP Security Descriptions (RFC 4568)… Dan Wing