Article ID:1573
Objectives
Some applications utilize multicast to deliver the same data to multiple clients simultaneously. An access point will broadcast multicast traffic one time rather than address it to each client individually. Clients do not notify the sending device whether multicast traffic was received or not. When power-save mode is enabled on a wireless client, this can lead to packets being lost without the sender or client knowing. The Beacon Interval and DTIM Interval setting are used to sync wireless clients and reduce packet loss.
An access point broadcasts a beacon as often as specified by the Beacon Interval setting, and contained in that beacon is a DTIM Interval. The DTIM Interval notifies a wireless client with power-save mode how many beacons till buffered multicast traffic will be broadcast by the access point. The wireless client keeps track of this DTIM Interval in order to wake-up and be available to receive traffic at the right time. Normally, an access point will immediately broadcast multicast traffic as soon as it gets it. However, if there is a single wireless device utilizing power-save mode connected to the access point, multicast traffic is buffered until the number of beacons as specified by the DTIM interval have been broadcast.
If no wireless clients are using power-save mode, DTIM Interval will have no effect. Multicast traffic is broadcast immediately by the access point.
The objective of this document is to show you how to configure Beacon Interval and DTIM Interval on the WAP200E.
Applicable Devices
• WAP200E
Step-by-Step Procedure
Configure Beacon Interval and DTIM Interval
Step 1. Using the graphical user interface of the access point, choose Wireless > Advanced Settings. The Advanced Wireless Settings page opens.
Step 2. Enter the delay in milliseconds between beacons to be broadcast in the Beacon Interval field.
Note: The DTIM Interval relies on the Beacon Interval. If there is a single wireless client utilizing power-save mode connected to the access point, increasing Beacon Interval will increase the length of time that multicast traffic is buffered before being broadcast. Otherwise, multicast traffic is broadcast immediately and Beacon Interval has no effect on multicast traffic.
Step 3. Enter the number of beacons that must be transmitted before buffered multicast data is broadcast in the DTIM Interval field. Increasing DTIM Interval decreases throughput and high values may produce undesirable performance in an application relying on multicast traffic.
Note: DTIM Interval is only used for multicast traffic when at least one wireless client that is connected to the access point is using power-save mode. This setting has no effect on unicast traffic.
Step 4. Click Save to have the Beacon and DTIM Intervals go into immediate effect.
