[127319] in North American Network Operators' Group
Re: Micro-allocation needed?
daemon@ATHENA.MIT.EDU (=?iso-8859-1?Q?Ask_Bj=F8rn_Hansen?)
Mon Jun 21 18:05:12 2010
From: =?iso-8859-1?Q?Ask_Bj=F8rn_Hansen?= <ask@develooper.com>
In-Reply-To: <05839B8C-571A-44C4-863C-BC03C0733E84@hopcount.ca>
Date: Tue, 22 Jun 2010 00:04:55 +0200
To: Joe Abley <jabley@hopcount.ca>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jun 21, 2010, at 23:55, Joe Abley wrote:
Everyone: Thanks for the replies regarding the /24 announcement from a =
"/20 allocated block". Yes, obviously the /20 announcement will handle =
the traffic, too. I'm a regular reader on NANOG and consistently =
impressed by the expertise on display and the speed with which it's =
generously handed out. :-)
> I'm interested in the idea of anycasting one of the pool.ntp.org =
herd-members. Every time I've suggested such a thing I've been told =
(paraphrasing) that a good (server, client) NTP session exhibits =
reasonable RTT stability, this constitutes, in effect, a long-lived =
transaction, and hence anycast is not a good answer unless you have =
confidence that the potential for oscillations is low, or that the =
frequency of the oscillations is very low (i.e. in a private network =
this might be a good answer, but across the public Internet it's a poor =
answer).
>=20
> Has the thinking changed, or did I just misunderstand?
I think the thinking on NTP [ see below ] is the same; but indeed when I =
wrote "possibly other UDP based services" experimenting with that was my =
idea, too.
I believe some of the CDNs are anycast based (Cachefly?) and they did =
some extensive tests with very long http transactions. (And I guess do =
a big test daily in running the service...).
However -- Much of the pool.ntp.org traffic is from SNTP clients where =
the NTP considerations don't apply. (In summary: SNTP =3D dumb client =
that just asks for the time now; NTP =3D clever server that keeps track =
of the time. The protocol is the same, but the usage quite different).
- ask
