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Posts: 1
Registered: ‎09-10-2014

DTIM vs too much bcast/mcast traffic

Hi, I have my DTIM interval set to 3 and my BCN interval set to 100ms, which to me means that given any STA goes into PS=1 mode, the AP has to queue up bcast/mcast for upto 3 BCN intervals, or 300msec.

 

Af each 300msec interval, the AP can release a bunch of bcast/mcast queued traffic and the STA is expected to be awake at the beingging of this exchange to get its data.

 

Now my questions is, what happens if the amount of realeased traffic acutually sucks up the entire BCN interval, or in other words, takes >100msec of time.

 

I understand that the ucast traffic is help off, but is the AP expected to then requeue any outstanding data until the next 300msec interval, or is it OK to carry over into the next beacon interval and the STA is to stay awake?

 

If the STA is to stay awake, how does it know that there is no more bcast/mcast data coming?

 

rjmiller

Guru Elite
Posts: 20,598
Registered: ‎03-29-2007

Re: DTIM vs too much bcast/mcast traffic

Please look at the post here:  http://wifi-insider.com/wlan/psd.htm for a detailed explanation.  In general increasing the DTIM is only used for VOIP clients and only based on manufacturer's recommendations for their VOIP devices.  Increasing it for better multicast performance is not used commonly.

 



Colin Joseph
Aruba Customer Engineering

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