Purchasing the correct IP address from an ISP

[atl021984]

Trying to figure out what class and how many IP address I need for a start-up company. The company will have 5 locations with 18-25 users at each location. So let's be safe and say 125 total users, which already includes growth. Each location will have a server or two, and the main location will hold most of the servers and storage. Also at each location there will be 2 All-in-One Printer/Scanner/Copier/FAX. Along with these 125 total users, each user's will have an IP phone. To take a wild shot and say 275-350 total devices will need an IP address.

So how many from an ISP would I need. 1 – 2 addresses or more? I'm lost on a company stand-point on how many the company should own. I am aware of subnetting within the network. Any information would be great. Thanks

 

[Lexluethar]

Sounds like someone's homework problem. Startup company with 5 locations? You are the network admin and don't know this? Forgive me for being blunt, but i think this is just a homework question.

Lets pretend for a second that you are being serious, or that maybe you'll learn something from this - so i'm going to move forward with my suggestion.

Okay the easiest and cheapest solution IMO would be to use NAT (network address translation). High end routers should be able to do this - or you can dedicate a windows server 2008 to accomplish this. It's suggested you use dedicated network equipment though considering servers don't have as much up time as a router.

NAT will take one IP address that your ISP gives you and can translate it into over 1,000 private IP address of your choosing. This is the cheapest solution because you aren't leasing out or purchasing multiple public IP's, you have one IP that everyone outside see's and your router will then forward the information on to the appropriate private IP address.

If you want to go old school you can purchase multiple IP's from your ISP and just use subnetting. With that though i don't know how may devices need to be on their own subnet. Would every location need their own subnet? You're the network admin, so these are things you need to plan for.