[NTLUG:Discuss] Broadcast IP address

[Ralph Green]

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