Re: [Tsv-art] [v6ops] [Last-Call] Tsvart last call review of draft-ietf-v6ops-ipv6-ehs-packet-drops-05

Fernando Gont <fgont@si6networks.com> Sat, 20 February 2021 05:09 UTC

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To: Tom Herbert <tom@herbertland.com>
Cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, Gorry Fairhurst <gorry@erg.abdn.ac.uk>, tsv-art@ietf.org, last-call@ietf.org, draft-ietf-v6ops-ipv6-ehs-packet-drops.all@ietf.org, IPv6 Operations <v6ops@ietf.org>
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From: Fernando Gont <fgont@si6networks.com>
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Subject: Re: [Tsv-art] [v6ops] [Last-Call] Tsvart last call review of draft-ietf-v6ops-ipv6-ehs-packet-drops-05
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Hi, Tom,

On 19/2/21 18:13, Tom Herbert wrote:
[....]>> xor add this:
>>
>>     [RFC7098] discusses how the IPv6 FLow Label can used to enhance layer
>>      3/4 (L3/4) load distribution and balancing for large server farms.
>>
>> right after:
>>      Thus, ECMP and Hash-based Load-
>>      Sharing should be possible without the need to process the entire
>>      IPv6 header chain to obtain upper-layer information to identify
>>      flows.
>>
> I don't why this is only a "should". 

This is not a requirement. We're mostly indicating possibility.


> Hashing of three tuple for load
> balancing works as described as evident by the fact it is in wide
> deployment (consider it's been in Linux stack for it's internal load
> balancing for several years and there's now over a billion devices in
> the world that do this).

LB based on the FL relies on:
* Appropriate implementation of the FL
* Use of the FL in load balancers

There has been (and still is) an interesting mix of cases where one or 
both of this simply do not happen.

See e.g.: https://blog.apnic.net/2018/01/11/ipv6-flow-label-misuse-hashing/

We're just the messenger here....

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492