[91045] in North American Network Operators' Group
Re: IP failover/migration question.
daemon@ATHENA.MIT.EDU (Andy Davidson)
Tue Jun 27 09:52:04 2006
In-Reply-To: <17548.55606.965693.497106@roam.psg.com>
Cc: Andrew Warfield <andrew.warfield@cl.cam.ac.uk>, nanog@merit.edu
From: Andy Davidson <andy@nosignal.org>
Date: Tue, 27 Jun 2006 14:51:30 +0100
To: Randy Bush <randy@psg.com>
X-SA-Exim-Mail-From: andy@nosignal.org
Errors-To: owner-nanog@merit.edu
Hi, guys
Very late reply, but this is a 'hot topic' in my space..
On 12 Jun 2006, at 04:02, Randy Bush wrote:
>> I'm trying to get a more clear understanding as to what is
>> involved in
>> terms of moving the IPs, and how fast it can potentially be done.
> can we presume that separate ip spaces and changing dns, i.e. maybe
> ten minutes at worst, is insufficiently fast?
Ten minutes at worst, only if everyone is behaving. Some of the UK's
largest (in terms of consumer customer numbers) ISPs disobey short
dns refresh times, and will cache expired or old records for 24(+?)
hours.
Popular web browsers running on popular desktop operating systems
also display extra-long dns cache time 'bugs'.
24 hours + outage whilst stale dns disappears will never do in
internet retail. BGP, two datacentres, both equivalent endpoints for
customer traffic, same IP space, and an e-commerce application which
will happily run 'active/active' is the holy grail, I think. The
problem isn't setting this up in IP, it's getting your commerce
application to fit this model (a problem I have today).
Best wishes,
Andy
