Re: [Dart] IPv6 Flow labels? (Re: RTP and non-RTP traffic on same UDP 5-tuple)
Brian E Carpenter <brian.e.carpenter@gmail.com> Thu, 12 June 2014 20:12 UTC
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Date: Fri, 13 Jun 2014 08:12:54 +1200
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: Harald Alvestrand <harald@alvestrand.no>
References: <8D3D17ACE214DC429325B2B98F3AE712076FD346C9@MX15A.corp.emc.com> <5398BF50.5040604@gmail.com> <539991B1.1020000@alvestrand.no>
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Subject: Re: [Dart] IPv6 Flow labels? (Re: RTP and non-RTP traffic on same UDP 5-tuple)
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Hi Harald, On 12/06/2014 23:40, Harald Alvestrand wrote: > Brian, > > you mentioned 6-tuples - with the link you gave, I assume you're talking > about IPv6 flow labels. > > Apart from the issues with remapping, the use of flow labels should have > many of the same aspects as the use of DSCP codepoints. > > Can you give us some idea of how the use (or not) of multiple flow > labels within a 5-tuple has been thought about in the IPv6 context? It hasn't, because the model is that the label will be the same for all packets in a given flow, and a flow is usually assumed to be identified by its 5-tuple. But there are words at the very beginning of RFC 6437 that intentionally leave room for breaking that assumption: > 1. Introduction > > From the viewpoint of the network layer, a flow is a sequence of > packets sent from a particular source to a particular unicast, > anycast, or multicast destination that a node desires to label as a > flow. From an upper-layer viewpoint, a flow could consist of all > packets in one direction of a specific transport connection or media > stream. However, a flow is not necessarily 1:1 mapped to a transport > connection. So the door is open for multiple labels for the same 5-tuple, but always remembering that the label might be used as part of a load-balancing mechanism (as discussed in RFC 6438 and RFC 7098). Also, here's the bad news, remapping cannot be completely excluded for the flow label. See http://tools.ietf.org/html/rfc6437#section-6 and in particular http://tools.ietf.org/html/rfc6437#section-6.1 Brian > > Harald > > > On 06/11/2014 10:42 PM, Brian E Carpenter wrote: >> On 11/06/2014 07:59, Black, David wrote: >>> In another message, Ruediger Geib asked (>), and I responded: >>> >>> -------------------- >>> >>>> Is the following correct: >>>> >>>> UDP_5-tuple-+--transport protocol 1----- >>>> | >>>> +--RTP session 1----- >>>> | >>>> +--RTP session 2-----+---RTP_stream_2.1 >>>> | >>>> +---RTP_stream_2.2 >>>> |... >>> Yes, that matches my understanding, although the author team would >>> like to >>> see discussion of whether it's a good idea to mix RTP and non-RTP >>> protocols >>> on the same 5-tuple - I'll copy your useful diagram into a separate >>> message >>> to start that discussion. >>> >>> -------------------- >>> >>> This is that message, and I want to thank Ruediger for drawing that >>> useful >>> diagram. >>> >>> The author team for draft-york would like input on whether the draft >>> should >>> discuss mixing of RTP and non-RTP traffic on the same UDP 5-tuple, >>> vs. using >>> separate 5-tuples (probably separate UDP ports) for RTP and non-RTP >>> traffic. >> One observation is that we should be thinking about a 6-tuple these >> days (see RFC 6437). I don't think it makes much difference to the >> argument. >> >> Another observation is when load balancing is in play, things get a bit >> more complicated, but to a first approximation using the same 5-tuple >> or 6-tuple will usually ensure that all the packets reach the same >> load-balanced destination, which is probably a good thing. >> >> Third, reverting to the diffserv discussion, the same 5-tuple >> should ensure that all the packets would be classified the same >> (if they cross a diffserv domain boundary and get reclassified). >> >> Brian >> >>> RTCWEB clearly intends to mix SCTP (via DTLS) and RTP traffic on the >>> same >>> 5-tuple see the last paragraph of Section 3.5 of >>> draft-ietf-rtcweb-transports-04: >>> >>> RTCWEB implementations MUST support multiplexing of DTLS and RTP >>> over >>> the same port pair, as described in the DTLS_SRTP specification >>> [RFC5764], section 5.1.2. All application layer protocol payloads >>> over this DTLS connection are SCTP packets. >>> >>> OTOH, concerns have been expressed about whether the not-exactly-elegant >>> demux processing specified in the reference (RFC 5764, Section 5.1.2) >>> ought >>> to be recommended as a good way of doing this multiplexing. >>> >>> Please comment, including whether mixing SCTP and RTP on the same UDP >>> 5-tuple is a good idea (some rationale for doing this sort of >>> multiplexing >>> onto a single 5-tuple can be found in Section 3 of >>> draft-york-dart-dscp-rtp-00). >>> >>> Thanks, >>> --David >>> ---------------------------------------------------- >>> David L. Black, Distinguished Engineer >>> EMC Corporation, 176 South St., Hopkinton, MA 01748 >>> +1 (508) 293-7953 FAX: +1 (508) 293-7786 >>> david.black@emc.com Mobile: +1 (978) 394-7754 >>> ---------------------------------------------------- >>> >>> >>> _______________________________________________ >>> Dart mailing list >>> Dart@ietf.org >>> https://www.ietf.org/mailman/listinfo/dart >>> >> _______________________________________________ >> Dart mailing list >> Dart@ietf.org >> https://www.ietf.org/mailman/listinfo/dart > > _______________________________________________ > Dart mailing list > Dart@ietf.org > https://www.ietf.org/mailman/listinfo/dart >
- [Dart] RTP and non-RTP traffic on same UDP 5-tuple Black, David
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Brian E Carpenter
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Dan Wing
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Black, David
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Brian E Carpenter
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Brian E Carpenter
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Black, David
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Dan Wing
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Dan Wing
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Black, David
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Dan Wing
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Ruediger.Geib
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Harald Alvestrand
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Ruediger.Geib
- [Dart] IPv6 Flow labels? (Re: RTP and non-RTP tra… Harald Alvestrand
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Ben Campbell
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Black, David
- Re: [Dart] IPv6 Flow labels? (Re: RTP and non-RTP… Brian E Carpenter
- Re: [Dart] RTP and non-RTP traffic on same UDP 5-… Brian E Carpenter
- [Dart] Protocols and port numbers (Re: RTP and no… Harald Alvestrand
- Re: [Dart] Protocols and port numbers (Re: RTP an… Brian E Carpenter