You’ve probably heard of Beacon Interval Setting – which is the time lag between beacons sent by your AP. Well, DTIM is abbreviated from Delivery Traffic Indication Message and is linked closely with your Beacon Interval Setting.
What is DTIM Interval and What Does It Do
DTIM is a message that is sent out after your router’s or AP’s beacon broadcast.
Multicast is used to deliver data to many clients at the same time and your AP or router will broadcast that data in one shot rather than sending it to each client individually. There are no messages sent by the clients if the data was received. This can lead to packet loss should the wireless client be on a power saving mode. The DTIM Interval and Beacon Interval help to reduce packet loss as well as help sync the wireless connected clients.
How Does DTIM Interval Work?
Your router buffers data and depending on the setting set on your router, will accordingly alert the client to ‘wake up’ to receive the data via the DTIM interval. In most cases, your router or wireless access point should broadcast multicast traffic when it reaches it, but a device on power saving mode will cause the multicast traffic to be buffered until a certain amount of beacons as defined by the DTIM interval has been broadcast.
DTIM Interval has no bearing on devices that are not on power saving mode as the AP will broadcast data immediately. Many devices, when in Power Sleep Mode, ignore messages sent by a Non-DTIM beacon, so that they can enjoy a longer ‘Sleep’ period, and enjoy a longer battery life. These devices are programmed to ignore the non-DTIM beacons and to ‘wake-up’ only for DTIM beacons so that they are able to then receive the messages being transmitted by the router.
How to Calculate DTIM Interval
Just like the case with beacon Interval, the lower the value of DTIM, the less ‘sleep’ your devices will receive, as they will constantly be receiving wake up calls. This way your devices will rarely go into ‘sleep mode’ whilst idling which will lead to a higher power consumption and a shorter battery life for your device.
DTIM interval is how many data transmissions are sent out with each beacon – to put it simply, if you place a value of 1 for your DTIM interval for every beacon – 1 DTIM will be broadcast every single time a beacon is sent out. If you place a value of 50 as your DTIM, it will broadcast after every 50 beacons.
If you want to calculate DTIM period, and your DTIM value is set at 1, then it will be sent out 10 times/ second.
How? Because the default setting for your beacon interval setting is 100ms (unless you change it), and if you have set your DTIM setting to be 1, it will be transmitted every 100ms. Similarly, if you have changed your beacon setting to 500ms, and your DTIM interval is set at 2, then you will broadcast DTIM Interval once every second.
What Is an Optimal DTIM Interval Setting
Your router usually comes with a default DTIM interval setting of 1 – 3. This is usually the best number to stick to and has proven to be the most stable. However, if you go to your Routers’ WIFI setup > Advanced settings, you should be able to access it to makes any changes if desired. The highest value on most branded routers is 255. However, you will have to set your Beacon Interval Setting prior to tweaking your DTIM Interval settings.
Determining which is the best DTIM Interval setting for you depends on what are your end goals. Are you looking to save your device’s battery life? If that is your intention, then you should set your DTIM interval value to be as high as possible. There are added bonuses to doing this – you can then play uninterrupted with HD gaming while your other devices ‘sleep’, enjoying a slight advantage in performance.
By setting your DTIM to the highest setting, you do increase your device’s battery life – and that is the biggest benefit, but you also have to keep in mind that not all routers can handle this. Why?
Because routers that are weaker may not be able to handle the long holding period, leading to data loss or even to your router crashing. You should ideally monitor both your device and your router’s wifi performance to check if all is running smoothly.
DTIM period value for Office Settings:
Start with a low value and slowly increase it if you are in a work space to determine the right balance between your device’s power consumption and the application’s broadcast utility needs.
DTIM period value for Time Critical Situations:
You can face poor performance or even time lags should your DTIM be too high in a time sensitive setting. A good example of this would be for medical use where time is of the essence.
When Should You Lower Your DTIM Interval Setting
If you can detect any drops in signal on your device due to a high DTIM Interval setting, you should lower the value until you are satisfied with the outcome.
If devices or certain household application start working a little weird, or you notice something is not right, lower your DTIM Interval value.
Application Which May Have Problems With High DTIM values
- Mirroring
- VoIP
- Airplay
- Other broadcast/multicast applications
If you are facing problems, check out the application’s specified DTIM recommended value.
Final Words
DTIM Interval is part of a long line of settings that can be adjusted to optimize your device’s wireless performance. As with most things, you can find the setting that works best for your devices through trial and error by tweaking the values until you find one that is perfect for you.
If you have tried it out, have any questions about DTIM Interval; leave a comment in the section below!