[NTLUG:Discuss] Broadcast IP address

[Dennis]

Ralph,
You are on track, for the static servers, you need to change the subnet mask
to what you indicated.  The problem is with the systems that obtain their
address from the DHCP server.  You need to make a change to the
configuration to specify the address range and subnet mask that will be
handed out.  Check out the option statements for broadcast address and
subnet mask.  I think that should do it for the options.  Next check out the
range statement.  This should specify what addresses are issued, but it also
specifies the subnet mask for the network, so you need to also change it to
the 255.255.254.0.  You can change the address range for assignment if you
want, but it should not be necessary.

After the changes are made to the DHCP server, restart it and then restart
each system that gets its address from the server.

Requests to the DHCP server are via a MAC broadcast, so knowing the server's
IP address is not necessary.

Dennis

-----------------------------------------
From: Ralph Green <sirable at gmail.com>
To: NTLUG Discussion List <discuss at ntlug.org>
Subject: [NTLUG:Discuss] Broadcast IP address
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Howdy,
I have a network I want to expand a bit with as little impact on the
users as possible. All LAN addresses are currently in the 192.168.4.x
range. I am adding a new VPN server and I am thinking of using
192.168.5.1 for its address. It looks like I need to adjust the
netmask on machines in the original LAN from 255.255.255.0 to
255.255.254.0. If I do that on a test machine, I can reach it from
the 192.168.5.x machines. I see the broadcast address has changed
from 192.168.4.255 to 192.168.5.255. If I make the netmask change on
the servers, including the DHCP server, will clients be able to renew
their leases? I am thinking they will broadcast on 192.168.4.255 to
get a renewal and they won't find a response. What would be a good
way to resolve this? The only thing I can think of offhand, is maybe
to add a new machine temporarily at 192.168.4.255 and forward packets
to 192.168.5.255, but I think that might be a bad IP address for a
machine on the network.
Do you have any suggestions,
Ralph



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