Subnetting Windows Server 2008 R2 Branch Offices

OddyIT
OddyIT used Ask the Experts™
on
I have 1 main office and 2 remote locations. I want to connect them as branch offices. But I don't know enough about subnetting.

Current situation
- Main Office : 10.10.0.0 / 255.255.240.0
- Remote A : 10.10.16.0 / 255.255.240.0
- Remote B : 192.168.0.1 / 255.255.255.0

It would be easier to keep the A-class network on the main office, because there are al lot of devices with fixes IP, but if need be I'll change everything. What I think it should be, and please correct me if I'm wrong.
- Main Office : 10.10.0.0 / 255.255.0.0
- Remote A : 10.11.0.0 / 255.255.0.0
- Remote B : 10.12.0.0 / 255.255.0.0

Are there any problems with this, is there something I'm missing or should look out for?
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Commented:
Nothing really wrong with it but you are using 64k IPs per subnet block.

Commented:
A class A subnet isn't 'subnetting' but using the entire one giant subnet.

If your remote offices need to connect via routers or VPN's, yea, you'll have problems.  They should be in their OWN subnet.-

Main Office : 10.10.0.0 / 255.255.255.0
Remote A : 10.11.0.0 / 255.255.255.0
Remote B : 10.12.0.0 / 255.255.255.0

Main office can use 10.10.0.1 - 254
Remote A can use 10.11.0.1 - 254
Remote B can use 10.12.0.1 - 254

Author

Commented:
The site will be connected through vpn-routers.

If I use this configuation, doesn't the main office have only 254 IP's. I need at leased three times as many IP's for the main office. For the remote sites, 254 IP's should be enough.

Main Office : 10.10.0.0 / 255.255.255.0
Remote A : 10.11.0.0 / 255.255.255.0
Remote B : 10.12.0.0 / 255.255.255.0

Main office can use 10.10.0.1 - 254
Remote A can use 10.11.0.1 - 254
Remote B can use 10.12.0.1 - 254
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Commented:
Ok.  Then do this-


Main Office : 10.8.0.0 / 255.255.252.0
 Usable- 10.8.0.1 - 10.11.3.254

Remote A : 10.12.0.0 / 255.255.255.0
 Usable- 10.12.0.1 - 10.12.0.254

Remote B : 10.13.0.0 / 255.255.255.0
 Usable- 10.13.0.1 - 10.13.0.254

Commented:
FYI, this might help you out a little...

http://www.subnetmask.info/

Commented:
Rereading this, what is wrong with the subnets the way they are....?

Author

Commented:
I tought I needed to change them so that i can connect them trough site-to-site vpn. And use branch office from windows server 2008 R2.

Commented:
No your router / firewall will handle that.

Commented:
The only reason to really change the ips would be if you wanted them to fit a design policy better.
What your doing with the subnets is basically just dividing the ips into local groups.  A router is used to connect these groups together.  

10.10.0.0./255.255.240.0 <> Router <> 10.10.16.0/255.255.240.0

If you were using 10.10.0.0/255.255.0.0 for both locations then it would be a bridge configuration.  You could have any address from 10.10.0.0 in either location.  This would create a large broadcast domain and have a negative performance impact.

10.10.0.0/255.255.0.0 <> bridge <> 10.10.0.0/255.255.0.0

So unless you have more sites you havent listed, or need to allocate more IP addresses to a site and want them to all be part of the same subnet, you really don't need to change anything.

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