Re: RtgDir review: draft-rtg-dt-encap-02
Erik Nordmark <nordmark@acm.org> Tue, 21 July 2015 15:23 UTC
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Subject: Re: RtgDir review: draft-rtg-dt-encap-02
To: Jamal Hadi Salim <hadi@mojatatu.com>, Erik Nordmark <nordmark@acm.org>
References: <CAAFAkD-vfrXA0ejLE7Gnk=q8wZbS4SzC7+=_TJY+qzTXv4R9OQ@mail.gmail.com> <559AB820.9000309@acm.org> <CAAFAkD8YugDgPoS_mt3H+nRoWHGz9TX+YocbmdRyPwpFOt_+2Q@mail.gmail.com>
From: Erik Nordmark <nordmark@acm.org>
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Date: Tue, 21 Jul 2015 17:21:50 +0200
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On 7/13/15 1:52 PM, Jamal Hadi Salim wrote: > Erik, > Sorry for the latency - this got buried because i wasnt on the cc so > my filters > gave it low prio. > > > On Mon, Jul 6, 2015 at 1:17 PM, Erik Nordmark <nordmark@acm.org > <mailto:nordmark@acm.org>> wrote: > > On 6/30/15 2:20 PM, Jamal Hadi Salim wrote: > > > [..] > > The design team tried to stay away from potentially contentions > discussion by putting firm recommendations in place. Thus > currently the document is more of "things to think about" and some > tradeoffs, and less of recommendations (and no requirements). > > Alia has asked for more of a list of choices for the protocol > designers, and this is definitely something which folks can help > with as we continue this work in the RTGWG. But I also think we > need to let the specific in-flight WGs (NVO3, SFC, and BIER) use > this document as input but figure out their own tradeoffs and answers. > > > Generally the message was as you described. > I probably should have used the term "guidelines" instead of > "recommendations". > I was looking for guidelines and i sometimes didnt grok them. > I liked some of the format in section 18. It provides context ("Here's > what a NIC does for TSO") > and then provides guidelines ("optional protocol fields should not > contain values that must > be updated on a per segment basis .."). I realize that this specific > example is > closer to implementation details - which may change (or get obsolete) > over time but it serves > as a good example of what i was trying to say. > I also realize this may be hard to keep consistent across the document > - so take it as input > of where it may make sense to use such formatting. I just realized the subject line saying draft-rtg-dt-encap-02. We did add some bullets at the end of most sections in draft-ietf-rtgwg-dt-encap-00. I don't know if those help, but hopefully they can serve as a prompt for getting even more concrete guidelines. > > > > Many Internet protocols use fixed values (typically > managed by the > IANA function) for their next-protocol field. That > facilitates > interpretation of packets by middleboxes and e.g., for > debugging > purposes, but might make the protocol evolution > inflexible. Our > collective experience with MPLS shows an alternative where > the label > can be viewed as an index to a table containing processing > instructions and the table content can be managed in > different ways. > Would it not be useful to provide a reference here? Just > reading this > has questions popping for me - who populates this tag-indexed > table of > instructions and could interop be impacted? > > The DT added the above text based on comments at the mike from > Stewart Bryant. I don't know if there is any reference for the > general concept. Anybody else know? > > In general this implies some control-plane mechanism to populate > the table. > > > Maybe an addendum to describe that the control-plane or some human > would administer > this would be useful. Let me ask for volunteers to craft some text tomorrow. > > Is there a reference to work which says quiet periods (which i > am implicitly > reading that in the text above) can be used to change the hash > selection? > I would think that one needs to closely observe packet trends > to make > such a decision. So please provide some ref to some scholarly or > engineering work. > > I don't know of citations to such work; perhaps my co-authors have > some. > I recall reading about using markers, but that was a long time ago. > > It would help i think to have some reference. I am not sure if this > applies: > http://simula.stanford.edu/~alizade/papers/conga-sigcomm14.pdf > <http://simula.stanford.edu/%7Ealizade/papers/conga-sigcomm14.pdf> Let me have a look. Thanks again, Erik > > cheers, > jamal
- Fwd: RtgDir review: draft-rtg-dt-encap-02 Erik Nordmark
- Re: RtgDir review: draft-rtg-dt-encap-02 Erik Nordmark
- Fwd: Re: RtgDir review: draft-rtg-dt-encap-02 Erik Nordmark
- Re: RtgDir review: draft-rtg-dt-encap-02 Jamal Hadi Salim
- Re: RtgDir review: draft-rtg-dt-encap-02 Erik Nordmark