Zeus Karravala, an analyst at The Yankee Group, recently wrote a blog about It’s Time for Companies to Take IP Address Management Seriously. Like Zeus, I find that spreadsheets are the most common tool that NetCraftsmen’s customers use for managing IP addresses. The spreadsheet is invariably out of date. A big reason is that only one person can edit the spreadsheet at a time (we’ve yet to see anyone using Google Docs for their IP Address management spreadsheets). This makes it difficult for a team to keep the spreadsheet up to date. Changes invariably happen that are never recorded.
Zeus didn’t mention DHCP, which can significantly reduce the need to manually track each device. A good DHCP product allows you to define a scope, which allows many devices to be automatically assigned IP addresses. The good products will also have an option to automatically register the device in DNS using the dynamic DNS mechanism.
It is also possible to create static DHCP entries, which assign a specific IP address to a device with the matching MAC address. This mechanism is useful for assigning IP addresses to things like printers. The benefit is that the printer’s configuration remains static, even if it moves and is assigned a new IP address. Now you have three products in one: a DNS/DHCP/IPAM (IP Address Management) product.
The network infrastructure devices, such as routers and switches and firewalls, can also be added to the IP address management system, either manually or with an automatic network discovery mechanism. The automatic mechanism guarantees that you have a complete and accurate view of the entire network address space. This is great for knowing when you are running out of address space in a given subnet.
If the DNS/DHCP/IPAM product can determine the switch port to which each device, and is loaded with location information for each switch port, you can also track the physical location of devices. It is up to you to determine how accurate the location information needs to be. It could be somewhat general, like “3rd floor, west”, or it could be more specific: “2nd floor, east, office 211B.” The challenge with location tracking is gathering the location information in the first place and the more general location information is much easier to gather and load into the system.
Finally, adding a good graphical interface to the product allows network administrators to easily see what addresses are used, which ones are vacant, and even look at the history of usage. It is nice to know when a subnet is getting close to full allocation and being able to address it before it causes a trouble ticket to be opened.
With the right systems in place, IP Address Management becomes much easier and dealing with spreadsheets. And because the address space is monitored and updated as it changes, you know that it is accurate. That’s what makes the DNS/DHCP/IPAM tools valuable.
-Terry
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Re-posted with Permission
NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under http://www.infoblox.com/en/communities/blogs.html
