DHCP: The Underestimated Network Service

If we told you there was an easy way to manage and control your devices and your network, you would probably laugh and walk away at first. In reality, there is…and what’s more, it is one that’s been there all along. DHCP, the Dynamic Host Configuration Protocol, is what you’re probably using to deliver IP addresses to devices that connect to your network. But it’s a lot more flexible, and a lot more powerful than you might think.

DHCP: The underestimated network service

One of the key internet standards, DHCP is best known as the tool that sets up vital network information on a device when it connects to a network. Using IP broadcast addresses, a device requests an IP address assignment from any DHCP server on a network segment, which responds delivering networking configuration data from a pool of addresses and from a list of necessary service addresses.

It’s a simple service, but it works. It’s why public Wi-Fi hotspots are ready to go as soon as you connect your phone, or why laptops on a business network all display the same clock time, and can access file servers and other business services.

How DHCP works

With DHCP, network devices get their own address and basic network configuration at the same time allowing them to reach core network services ending up ready to operate as they are connected. It’s a reliable and easy way of providing network configuration information to devices beyond your control, reducing network management overhead. It’s plug-and-play for your network. As devices leave the network, their addresses are returned to the pool, ready for reuse. Other, more trusted, devices can be allocated specific addresses based on the identity of a device’s network hardware.

The benefits of a modern DHCP implementation make it possible to manage very large networks – as well as working with cloud-hosted infrastructure at scale. As devices arrive and leave the network, DHCP systems update the local DNS and IPAM databases, allowing other systems to respond appropriately to planned load, or in conjunction with network quarantine tools to ensure devices have the appropriate software updates. It can even form part of your overall security architecture, working with other network devices to ensure intruders cannot masquerade as trusted devices.

Using DHCP to control networks

Centralizing IP address delivery makes it easier to control, ensuring devices are issued the right address and use the correct core network services such as Gateway, NTP and DNS. One option is to re-allocate addresses to the same devices as they reconnect, based on the address they’re allocated on first connection. Alternatively, you can just use dynamic addresses allocation to give a device a random address each time it connects, letting you use a smaller pool of addresses than the number of possible devices connecting and making sure you’re being economical with a limited number of available addresses. Smart resource allocation like this makes sense when managing consumer Wi-Fi, for example, where users are connected only for a few minutes or for a few hours.

If you’re building a complex network architecture, and you’re worried about IP addressing issues like misconfiguration, subnet masks, and virtual network segmentation, then DHCP can reduce risk, automating the process of assigning devices to the correct network segments. By linking DHCP to network management tooling, you can ensure that the right information is delivered to the network stack on the right device at the right time. A modern DHCP server will offer APIs that can be used to integrate with many different network management platforms. It’s also important to link DHCP tooling to your security infrastructure, as it can be used to blacklist unwanted devices, or quarantine at-risk systems until they are updated.

DHCP is everywhere

Modern DHCP is integrated deeply into a range of different services, from Active Directory to network access control. Having a DHCP server that offers API access to other services, and is integrated with IPAM tooling, makes a lot of sense. Knowing what devices are connected to your network, and ensuring they are segregated appropriately lets you manage BYOD effectively.

Using the latest IP address tooling, combining DHCP with IPAM and DNS in a single network appliance, means you’re able to control addressing in one place. If you’re in a regulated industry, you also have the option of tying it to configuration management tooling and using it as the basis for ITIL-compliant management of your network, using a CMDB to manage your addresses. The latest solutions are also able to improve reliability, supporting failover with high-availability implementations, keeping DHCP up and running.

Using DHCP in public

If you offer public Wi-Fi then getting DHCP right is key for a good customer experience. If you’re not able to support all the devices that are likely to connect – and quickly – then users are going to be unhappy, and unhappy users are unhappy customers who are unlikely to come back. You’ll need as well to ensure that your DHCP tooling is able to support a wide range of different DHCP clients, which may well handle the same responses differently. It’s also essential if you’re offering Wi-Fi at massive scale, in a stadium or a concert hall, where tens of thousands of users may be connecting and disconnecting over a very short span of time.

What it all adds up to is a service that when used to its full, can take much of the weight off the minds of network administrators. DHCP is the original self-service network tool, but it pays to keep on top of it, and not leave your users waiting.

6 February 2019 If we told you there was an easy way to manage and control your devices and your network, you would....

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DHCP: The underestimated network service