North American Network Operators Group

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Re: IP failover/migration question.

  • From: Andy Davidson
  • Date: Tue Jun 27 09:52:46 2006

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,