new T1 line

Barry Margolin barmar at genuity.net
Thu Aug 30 18:09:34 UTC 2001


In article <9mlrgq$4tm at pub3.rc.vix.com>, babu <babu at crestecdigital.com> wrote:
>We are going to replace our T1 line with another ISP's T1. So our web
>servers/sites network/IP addresses will change. Is there anyway we can get
>our new T1 line with no down time or least down time of our web servers?
>Because DNS updation takes 2,3 days , what should I do to make the servers
>available on the internet.

You'll have the least downtime if you can run both T1's simultaneously for
a short while.  Configure your servers with addresses from both ISP's
address blocks.  After the new line comes up, change your DNS to give the
new server addresses.  Once the TTLs on the old addresses runs out you can
shut down the old T1.

If you can't run them in parallel, read on.

Are your nameserver addresses in the block that's switching?  If so, get
some external slave nameservers (perhaps from the new ISP) whose addresses
won't be changing when you switch and update your registration to include
them now.  Have them configure their slaves to pull from both the old and
new addresses of the master, i.e.:

zone "yourdomain.com" {
  type slave;
  masters {<CurrentMasterAddress>; <NewMasterAddress>;};
  ...
};

The day before the switch, reduce your TTLs to something short like 15-30
minutes.  When you bring up the new T1, update your DNS to have the new
addresses.  Your server should send a NOTIFY to the ISP's slave servers and
they'll pick up the change shortly.  After the TTL expires, everyone should
be going to your new server.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.


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