Mailinglist Archive: opensuse (3031 mails)

[James Knott <james.knott@xxxxxxxxxx>]

James D. Parra wrote:
> Would this work if I used 192.168.50./23 to give me a range from
> 192.168.50.0 to 192.168.53.0? Increasing the range from 254 addresses to 510
> addresses would work for me.
>
> Again, many thanks. This is a great list.
>
>   
A /23 subnet mask will give you 512 addresses and /22, 1024.  The /x
simply tells you how many of the 32 address bits are reserved for the
network address and the remaning (32-x) can be used for computers,
routers etc.  So, with /23, you've got 23 network address bits and
32-23=9 address bits for the computers.  2^9=512 etc.  Going the
otherway, if you had 1000 computers, the smallest network you could use,
would require 10 address bits for the computers, because 2^10=1024 is
the smallest power of two that will contain sufficient addresses.

So, to get back to your original question, if you can get by with less
than 510 addresses, the solution is quite simple.

1) Set your DHCP leases to a short period.
2) Set the subnet mask, in the DHCP server for the 192.168.0.0 network
to /23
3) After all the computers have had time for the DHCP leases to be
renewed, with the new mask, increase the DHCP pool in the 192.168.0.0
network to include the 192.168.1.x range.  Servers and other devices
that don't use DHCP may have to be reconfigured at this point.
4) Move the 192.168.3.0 users over, either by manually connecting them
to the 192.168.0.0 network or simply connect the two networks through a
switch and turn off the DHCP server on the 192.168.3.0 network.  All the
hosts will move over when they renegotiate the DHCP lease.  You may have
to assign an alias IP address to servers etc., during the transistion.
5) Set the DHCP lease period back to normal.

Repeat step 4 for the 192.168.23.0 users.

You can avoid adjusting leases and some other issues, if you can arrange
for a window where you can simply make all the changes at once and
simply tell the users to reboot etc., the next morning.  Don't forget,
you may also have some DNS issues to worry about.  Again here, an alias
address can help.  Simply configure the server with both old and new
addresses and then change the DNS records.  After allowing time for the
DNS caches to expire, you can remove the aliases.  If you have routers
in there, you might expect some ICMP redirects telling computers to
communicate directly to servers etc., until all the changes have been made.




-- 
Use OpenOffice.org <http://www.openoffice.org>
-- 
To unsubscribe, e-mail: opensuse+unsubscribe@xxxxxxxxxxxx
For additional commands, e-mail: opensuse+help@xxxxxxxxxxxx