Do I have this IP figured right

[350ztn]

Looking for a solution for a customer adding a new building and expanding an office. current IP addressing is as follows...
10.245.1.0/25
10.245.1.128/28
10.245.1.144/28


I need to expand the 10.245.1.144 IP from a /28 to a /27 Can my useable IP range then be 145-175, is that an issue?

 

[KiscoKid]

If you want to change your address mask, the usable IP range changes to:

10.245.1.129 - 10.245.1.158

which obviously overlaps with 10.245.1.128/28

Alternatively you can use 10.245.1.160/27 instead to prevent this overlap.

 

[350ztn]

Going to the 10.245.1.160 wouldn't be that big of a deal if I didn;t have a novell server and ATM to contend with. change the IP's on those present some issues. If I have the overlap I would loose 2 IP's in the overlap, right? That is acceptable to lose 2 IP's but does that present an routing problems with the overlap?

 

[vipergg]

You cannot overlap subnets , the router will not even let you configure the interface if it overlaps with another , must keep within the network for the mask you are using. The mask determines what addresses fall within the subnet .