DTIM is a networking term that stands for delivery traffic indication message. This term is related to beacons – or packets of information that is broadcast through a network. In more technical terms, DTIM is a multiplier of the beacon interval. To really understand what all of this means in networking, it’s important to break down each element and term to see how it all works together.
What Is Beacon Interval?
To begin to understand what DTIM is and its role in networking, it’s first to have a grasp of beacon interval. Beacons contain information that has information about the network and is used to synchronize the network. How often this information is broadcast is determined by the beacon interval. This setting can be customized through a router’s advanced settings menu. Settings may vary and can be adjusted to optimize performance. The default beacon interval for most systems is 100, which means that a beacon is set every 100 milliseconds. If the beacon interval is changed to 50, this means that a beacon is sent every 50 milliseconds.
How Does This Relate to DTIM?
DTIM is a message that is sent with beacons. This message essentially notifies a computer that information has been delivered and will “wake up” a computer or device from a sleeping state. Just because a beacon is sent, however, doesn’t mean that this message is also delivered. This rate can be changed by adjusting what is known as the DTIM interval, or DTIM period. The DTIM interval can be adjusted to determine when the message is sent. If the DTIM interval is set to 1, for example, a message is sent with every beacon. If the DTIM interval is set to 10, a message will be sent with every 10 beacons.
What Does All This Mean for a Network?
Configuring settings that will allow fewer DTIMs to come through can help preserve battery power by up to 20% if a device that hibernates goes into Power Saving Mode. Getting fewer beacons pushed through will allow the device to remain in this mode without being awakened to receive the transmission. However, sometimes changing these settings can result in connectivity problems, particularly when multiple devices are connected to a network. In most cases, the default settings should be fine for most networks. However, if there are problems with the battery that aren’t hardware related, the DTIM interval may need to be adjusted. If after adjusting, performance problems are observed, the setting will need to be tweaked further to balance the battery life with reliable connectivity.
Final Thoughts
Even if you don’t plan on accessing your router’s advanced settings, it’s always a good idea to be familiar with the various settings so that if a performance issue does arise, you can act immediately without losing your connection. DTIM for the most part can be left on its default settings but in some cases can be used to improve performance when adjusted along with the beacon interval.
Sources
http://w3techie.com/optimizing-your-wifis-dtim-interval/ http://www.juniper.net/documentation/en_US/junos12.1x44/topics/concept/wlan-ax411-access-point-dtim-period-understanding.html http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_01001110.html