Have you noticed that the battery life of your device isn’t what it used to be? Sure, over time your battery will discharge faster and will eventually need to be replaced, but before you pull out your wallet to purchase a pricey new battery for your laptop or smartphone, read on to find out how the DTIM interval may affect your battery life, and the benefits (and drawbacks) of changing this setting.
What is DTIM?
Before we get into what the DTIM interval means, it helps to establish what DTIM is. DTIM stands for Delivery Traffic Indication Map (sometimes written “message”), and it’s carried inside an access point’s beacon frames. In short, it tells a power-saving device when buffered broadcast and multicast data is about to be sent, so the device knows when to wake up and listen for it.
What is DTIM interval?
The DTIM interval (or DTIM period) controls how often a DTIM beacon - the one that triggers delivery of buffered broadcast and multicast traffic - is sent. It works hand in hand with the beacon interval. If your beacon interval is 100, a beacon goes out roughly every 100 ms. The DTIM interval then determines which of those beacons is a DTIM: set it to 1 and every beacon is a DTIM, set it to 3 and every third beacon is a DTIM.
How DTIM intervals affect performance
A shorter (lower) DTIM interval means buffered broadcast and multicast traffic is delivered more often, so it can feel more responsive. Keeping the DTIM interval at 1 with a beacon interval of 100 favors responsiveness. The drawback is battery life: because devices have to wake for every DTIM beacon, a low value can measurably increase power use on phones, tablets, and other battery-powered gear.
A higher DTIM interval lets devices stay in power-save mode longer, improving battery life. The trade-off is added latency for broadcast and multicast traffic, which can occasionally affect things like media streaming or device discovery on busy networks.
For the most part, many users won’t need to adjust the default beacon and DTIM interval settings unless there is a loss in connectivity or an issue with battery life. If this setting does need to be adjusted, this can be done through the router’s advanced settings.
Final thoughts
The DTIM interval is one of several advanced router settings you can use to fine-tune wireless performance. For most home networks the default works well; change it only if you are specifically trying to improve battery life or troubleshoot a responsiveness issue. For the underlying concept, see our explainer on what DTIM is.
