IP renumbering

[Newman, David]

>=20
> Hello:
>=20
> I may need to renumber my shop for the new C-class set of=20
> IPs. I have 2 RH=20
> Linux 8.2.3 DNS servers and 2 RH Linux 7.1 hosts, 1 M$ W2K=20
> Server, 1 M$W2K=20
> Professional, 1 M$ W98, and 1 M$ XP host with about 150 IPs=20
> in use among them.
>=20

We do this about every six months.  Don't ask me why.

I find the easiest way to do this is to dump the new
address space onto the same ethernet as the old
address space.  Assign your DNS servers new IP addresses
in the new address space but put the addresses on
secondary interfaces.  That way your servers can
respond to either IP network with the same ethernet
card.

The next step is to change the IP addresses of your
nameservers at the registry.  I usually do them
one at a time.  You will see DNS requests taper
off on the old address and pick up on the new address.

Change your default gateway from the router on the
old network to the router on the new network.  This
can happen at any time and won't affect anything.
DNS packets are quite happy coming on from one ISP
and going out over another.

At some point in the future clean up your servers
by changing the secondary interfaces to primaries
and getting rid of the old network entirely.

Your various hosts can be updated in a similar
manner with the only exception of not having to
deal with the regsitry.

-Dave