Today's topic is in response to and a continuation of my actifit post from yesterday.
In short, we had a power outage covering the airport. After it came back on, all devices had to renew their IP addresses. Some however took addresses that were supposed to be reserved for something else, like a printer. This can all be easily managed with DHCP. But it was poor management of the DHCP that ultimately caused yesterday's massive headache.
The Lesson
A computer network is a means of connecting a number of machines together. A "Network Neighborhood" if you will. And in that neighborhood, each machine has its own address to identify it.
Early on in networking, each machine had to be manually assigned an address and you had to keep track of what was used and what wasn't so you didn't have duplicate addresses.
But in the 90s a new protocol (or way of doing things) was developed called Dynamic Host Configuration Protocol, or DHCP. This is a server-side utility that assigns and manages all addresses on its network.
But what if you need to set some IP addresses manually (aka static IP) so a device's address doesn't change? Not a problem. You can specify a range for static IPs and a different range for Dynamic IPs.
The Problem
When setting these ranges, be sure the people who have access to the network devices know about and comply with the chosen configuration standard. DHCP has power over every address it controls and will take addresses from anything set static in its range if needed. This is where yesterday's problem came in.
When our DHCP range was too full to allow more devices a few months back, our networking team found a range of ports not in use in the static portion and gave them to DHCP.
Only they were in use. They opened up our IPs for printers to everything else. I'm actually unpleasantly amazed at this activity and at how many times I had to explain that these ports were indeed in use. So they removed them at my request. All good now right?
Well apparently not. After the power outage, all those changes disappeared. Phones, PCs, and printers were all fighting for IPs. I had to explain again what I needed them to do.
The Conclusion
DHCP is a great thing. Of course it is. It's been around for over 20 years and it's used successfully everywhere. It takes much of the headache out of managing a network. But as with any automation software, it needs to be handled properly. In any business with a large IT department, this should never be a concern. Thankfully there are plans to upgrade our network to better handle all the equipment.
When I have another IT issue to gripe about, I'll share it with everyone on a similar manner.