Add subnet to network

So i need to expand the main network for a client. They currently are on a 10.10.10.0/24 scheme. If i'm correct, the process would involve changing them to a /23, which would open up the 10.10.11.0 subnet to be used by DHCP. I know its not that simple, so i wanted to review what needs to be done in order to accomplish this. Currently everything is setup with subnet masks of 255.255.255.0 which will need to be changed to .254 for anything with a static IP address? The gateway is currently 10.10.10.1, so i should not need to modify anything on that end, and then add an additional DHCP scope to include the 10.10.11.X addresses.

I know i'm overlooking steps, so feel free to list/ask me questions.

As always, i appreciate the help.
altitudetekAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Thomas GrassiSystems AdministratorCommented:
If most of your devices are DHCP clients then drop the lease time down to less than an hour before your ready to change.

Change all the static ip addresses you have defined. Servers Printers etc.

your new network will be

10.10.10.0
subnet mask 255.255.254.0
mask bits 23
number of subnet 32768
number of hosts 510
network address 10.10.10.0
first usable address 10.10.10.1
last usable address 10.10.10.254
broadcast address 10.10.11.255

Create a spreadsheet with all the know ip address ranges and static and reservations you may have then you will have a good check off list.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Seth SimmonsSr. Systems AdministratorCommented:
if it's /23 then the last usable address would be 10.10.11.254
10.10.10.254 would be /24

shouldn't have to create new dhcp scope for the .11 range; the .10 should cover it when changing to /23
0
altitudetekAuthor Commented:
Both good to know, in terms of the static addresses are there anything i need to concern myself with regarding gateway and subnet. As far as i could think changing the subnet mask and leaving the gateway (since it remains unchanged) was all that would require. Nothing would change on the firewall aside from the same change to a /23 network
0
What were the top attacks of Q1 2018?

The Threat Lab team analyzes data from WatchGuard’s Firebox Feed, internal and partner threat intelligence, and a research honeynet, to provide insightful analysis about the top threats on the Internet. Check out our Q1 2018 report for smart, practical security advice today!

Thomas GrassiSystems AdministratorCommented:
Only change will be the subnet mask.

As seth says you do not need to create a new scope

Just modify the existing scope when your ready.
0
Craig BeckCommented:
Be careful with this.  It's straight-forward but you will be making a couple of IP addresses usable which would normally be a broadcast and network address - 10.10.10.255 and 10.10.11.0.

Because you're changing the mask to /23 these addresses will be valid host addresses, BUT some devices won't like using them if they are assigned via DHCP as some clients don't work out the broadcast address correctly.  To mitigate this I would exclude those addresses from the scope.

Also, if you're using a Microsoft DHCP server you will have to delete the scope and recreate it as you can't adjust the subnet mask once the scope is created.  If you have reservations and exclusions that you want to keep you should export the scope using NETSH then edit the output to include the new subnet mask and import the scope again using NETSH...

netsh dhcp server \\YOURDHCPSERVER scope 10.10.10.0 dump >c:\dhcpscope.txt

Open in new window


Edit the subnet mask for the scope in the c:\dhcpscope.txt file then save.

Delete the scope from DHCP then...

netsh exec c:\dhcpscope.txt

Open in new window

0
altitudetekAuthor Commented:
Thanks for the input. I'll have to create a good spreadsheet for all the static's on the network but it looks like i have what i need to move forward with this.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Windows Networking

From novice to tech pro — start learning today.