Re: [v6ops] WG Doc? draft-gont-v6ops-ipv6-ehs-packet-drops

[Tom Herbert <[e-mail]>]

On Sun, Mar 13, 2016 at 8:01 PM, Warren Kumari <[e-mail]> wrote:
>
>
> On Mon, Mar 14, 2016 at 9:54 AM Tom Herbert <[e-mail]> wrote:
>>
>> On Sun, Mar 13, 2016 at 5:51 PM, Brian E Carpenter
>> <[e-mail]> wrote:
>> > On 14/03/2016 09:59, Tom Herbert wrote:
>> > ...
>> >> the point of using flow label is
>> >> that it eliminates the need to parse extension headers in the first
>> >> place for the ECMP use case. It would be nice if this benefit was and
>> >> the need for flow label support were better enunciated in the draft.
>> >
>> > I'll be the least likely person on the planet to disagree with that,
>> > but it is already part of the IPv6 standards (RFC6437 - see 2nd and 3rd
>> > paragraphs of the Introduction) and has been in the IPv6 Node
>> > Requirements
>> > since 2011 (RFC434).
>> >
>> Brian,
>>
>> These are good descriptions flow label usage, but I don't see that
>> they set requirements as to 1) whether end host must/should/may send
>> non-zero flow labels with flow entropy 2) whether ECMP devices
>> must/should/may use non-zero flow labels as input to their hash, or 3)
>> if hosts use the flow label for EMCP must/should/may they parse any
>> deeper to extract additional L4 entropy. RFC6438 comes close and
>> answering #1, but that RFC is only applicable to tunnels.
>>
>> Pertaining to this draft, there is an observation that flow labels
>> would obviate the need for middle boxes to parse the header chain,
>
>
> I think I must have missed something somewhere / lost the plot -- which
> draft is "this" draft? draft-gont-v6ops-ipv6-ehs-packet-drops?
> I don't think that draft-gont-v6ops-ipv6-ehs-packet-drops says that at all
> -- if the *only* thing that the middlebox is doing is load-balancing / ECMP,
> then this may be true, but in many cases "middleboxes" (a term which seems
> about as vague as "thingies") are doing many other things, including
> filtering, encapsulation, translation, monitoring / measurement,
> "optimization", prioritization, etc.
>
Section 4.1.2 of draft-gont-v6ops-ipv6-ehs-packet-drops-03 discusses
ECMP. ECMP is a fundamental feature in switches, we currently rely it
on to get good load balancing across network fabrics.

> But, as I said, I suspect I've lost the plot somewhere along the line...
> W
>
>>
>> however the draft also states historically neither end nodes nor
>> routers support. It seem like there should at least be a
>> recommendation in "Future work"  section on how to attain widespread
>> support flow label.
>>
>> Thanks,
>> Tom
>>
>> >     Brian
>>
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