nanog mailing list archives

Re: ECN

From: Saku Ytti <saku () ytti fi>
Date: Wed, 13 Nov 2019 21:35:37 +0200

On Wed, 13 Nov 2019 at 18:27, Matt Corallo <nanog () as397444 net> wrote:

This sounds like a bug on Cloudflare’s end (cause trying to do anycast TCP is... out of spec to say the least), not a 
bug in ECN/ECMP.


Not true. Hash result should indicate discreet flow, more importantly
discreet flow should not result into two unique hash numbers. Using
whole TOS byte breaks this promise and thus breaks ECMP.

Platforms allow you to configure which  bytes are part of hash
calculation, whole TOS byte should not be used as discreet flow SHOULD
have unique ECN bits during congestion. Toke has diagnosed the problem
correctly, solution is to remove TOS from ECMP hash calculation.

-- 
  ++ytti

Current thread:

ECN Baldur Norddahl (Nov 11)
- Re: ECN Owen DeLong (Nov 11)
- Re: ECN Toke Høiland-Jørgensen via NANOG (Nov 13)
  - Re: ECN Matt Corallo (Nov 13)
    - Re: ECN Hunter Fuller (Nov 13)
    - Re: ECN Todd Underwood (Nov 13)
    - Re: ECN Baldur Norddahl (Nov 13)
    - Re: ECN Mikael Abrahamsson via NANOG (Nov 13)
    - Re: ECN Baldur Norddahl (Nov 13)
    - Re: ECN Toke Høiland-Jørgensen via NANOG (Nov 14)
    - Re: ECN Saku Ytti (Nov 13)
    - Re: ECN William Herrin (Nov 13)
    - Re: ECN Lukas Tribus (Nov 13)
    - Re: ECN Saku Ytti (Nov 14)
    - Re: ECN Tore Anderson (Nov 13)
    - Re: ECN Warren Kumari (Nov 13)
    - TCP and anycast (was Re: ECN) Anoop Ghanwani (Nov 13)
    - Re: TCP and anycast (was Re: ECN) Bill Woodcock (Nov 14)
    - Re: TCP and anycast (was Re: ECN) William Herrin (Nov 14)
    - Re: TCP and anycast (was Re: ECN) Randy Bush (Nov 14)
    - Re: TCP and anycast (was Re: ECN) Christopher Morrow (Nov 14)

(Thread continues...)