nanog mailing list archives
Re: TCP and anycast (was Re: ECN)
From: William Herrin <bill () herrin us>
Date: Thu, 14 Nov 2019 18:26:02 -0800
On Thu, Nov 14, 2019 at 1:10 AM Bill Woodcock <woody () pch net> wrote:
On Nov 14, 2019, at 7:39 AM, Anoop Ghanwani <anoop () alumni duke edu>
wrote:
RFC 7094 (https://tools.ietf.org/html/rfc7094) describes the pitfalls &
risks of using TCP with an anycast address. It recognizes that there are valid use cases for it, though.
Specifically, section 3.1 says this: Most stateful transport protocols (e.g., TCP), without modification,
do not understand the properties of anycast; hence, they will fail
probabilistically, but possibly catastrophically, when using anycast
addresses in the presence of "normal" routing dynamics.
This can lead to a protocol working fine in, say, a test lab but
not in the global Internet.
On Thu, Nov 14, 2019 at 12:25 AM 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),
No. We have been doing anycast TCP for more than _thirty years_, most of
that time on a global scale, without operational problems. Hi Bill, Not to put to fine a point on it but Baldur and Toke's scenario in which anycast tcp failed, the one which started this thread, should probably be classed as an operational problem. It is possible to build an anycast TCP that works. YOU have not done so. And Cloudflare certainly has not. Regards, Bill Herrin -- William Herrin bill () herrin us https://bill.herrin.us/
Current thread:
- Re: ECN, (continued)
- 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)
- Re: TCP and anycast (was Re: ECN) Randy Bush (Nov 14)
- Message not available
- Re: ECN Toke Høiland-Jørgensen via NANOG (Nov 13)
- Re: ECN Matt Corallo (Nov 13)
- Re: ECN Anoop Ghanwani (Nov 13)
- Re: ECN Owen DeLong (Nov 13)
- Re: ECN Toke Høiland-Jørgensen via NANOG (Nov 14)
- Re: ECN Jon Lewis (Nov 13)