Christopher J. Knowles wrote:
Once again, I appear, hat in hand, prostrate at the altar of the amassed
knowledge of TriLUG...
My company is being forced to move ISP's. (Level3 is dropping anything so
rinky dink as our 300 people...) It's already been decided by the muckety
mucks who we're going with...
My problem is this...
The change over will happen sometime in the next few months... and I would
like to make sure that inbound e-mail and web traffic doesn't get lost. (or
at least that the loss is a minimum...)
Now, we run our own DNS servers, and I'm perfectly capable of maintaining
normal events, but this is a little bit beyond me.
So my question is this... what's the right sequence of events to make
everything go smoothly?
CJK
Having shepherded this process for several different companies, I would
suggest that the most important thing is to develop a relationship with
a good technical person at the new ISP. Talk to them several times
during the week leading up to the switch to make sure everything is in
place. If you can get a visit from a real live engineer to verify that
everything is physically connected and ready to go, well in advance of
your switch, everything is more likely to go smoothly. Even so, you
should plan for something to go wrong, because it usually does.
If they can plan to have the circuit turned up more than 1 week in
advance, you can test the switchover yourself -- try to bring the new
circuit online one evening or weekend, with enough time to spare before
your real switchover occurs. If you have spare equipment or are getting
new equipment (CSU/DSUs, routers, etc) this is a little less hairy.
ISPs have to work with whoever owns your building's demarc to get
everything right, and telecom companies do not play well with each
other. Verifying in advance that the circuit and the routers are
properly configured will save you from a stressful late night.
For minimum email disruption, you should find someone who will queue
your email for free -- most likely your new ISP. If free isn't
available, I have had good results with magma -- www.magma.ca. All that
is required, once they have agreed to queue your email, is to add their
server as a lower-priority MX record. This is good to have in place
even when you aren't switching ISPs.
For minimum DNS disruption, lower your zone's TTLs to about 15 minutes,
several days in advance of the switch. This will force all downstream
clients and DNS servers to look up your DNS records nearly every time,
rather than using cached lookups. Hosting your own DNS puts you in a
good position, not having to rely on your domain's registrar to switch
DNS servers.
Good luck!
Matt
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