To function properly, each IP address in a TCP/IP network needs to be unique, otherwise the network won't know where to send packets. As organizations grow, keeping track of subnets assigned to each site and IP addresses assigned in each subnet becomes a complex and time-consuming task. Eventually, administrators realize Microsoft Excel is not the best tool for the job. Usually a few years later, IT managers realize the cost of this administrative labor exceeds the cost of a more appropriate tool. Thus the call to you -- the organization's trusted VAR or consultant -- to help them
The basic function of an IPAM tool is to track IP addresses so that network administrators can know and report on such things as how many IP addresses are in use, how many are available and how volatile the changes are. But it's also good to know:
- What device is the IP address assigned to?
- Who is the owner of the device and how can you contact them?
- What VLAN is the device assigned to?
- What site, region, country or geography is the IP address in?
- Is the IP address visible on the Internet, or is it part of a DMZ or other security zone?
- If the IP address is dynamically assigned, how long is the lease and when does it expire?
Some tools can also manage requests for IP space or addresses, or be connected to the customer's help desk ticketing system. This is important for large organizations that have thousands of servers with manually configured static IP addresses.
Another basic set of features you should require is that the tool be accessible to multiple network administrators over the network, with a role-based security model so that different individuals (e.g. server administrators) or groups can request addresses through a Web-based system, assign subnets, manage the system itself and get reports. Of course, there can be overlap in these groups, depending on your customer's needs.
While keeping track of dynamically and statically assigned addresses and subnets is the major focus of these tools, it's not the only feature. Obviously, different tools have different focus and forte, but consider some of these integration points as you evaluate your customer's needs.
Some tools integrate well with systems like Microsoft's Active Directory or other enterprise directories like LDAP. This allows IP addresses to be associated with objects in the directory like specific users or servers and printers, etc.
Along with this, integration with DNS and DHCP allows some tools to provide a useful and functional Dynamic DNS (DDNS). This association lets you automate name resolution, even for rapidly changing DHCP pools.
Finally, some tools take a security angle and attempt to control the allocation of addresses to prevent rogue devices from gaining access. Although I'm not aware of a scalable, integrated product that does this today, I suspect most IPAM vendors will try to support IEEE 802.1x Port Authentication in the future for a complete end-to-end security and IP management infrastructure.
About the author
Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years of experience in the networking industry. He is co-author of several books on networking, most recently,CCSP: Secure PIX and Secure VPN Study Guide, published by Sybex.
This was first published in January 2007