802.11n timing question

RICHARD MESSINGER · ‎09-16-2008

Customer is setting up a wireless 802.11n controlled environment for some equipment. Response time from the wireless device and a wired device is critical.

In his testing, he is seeing a periodic delay every 60 seconds when sending packets between these two devices. He does not observe this behavior when both devices are wired.

For simplicity, he does not have any encription between the wireless device and the AP.

Is this delay being cased by some BDPU packet processing or is there something else going on? Reading acouple of white papers on 11n, I am not seeing other possibilities. They have supposedly turned off beaconning, but I have not independantly checked.

Any other thoughts? What is happening every 60 seconds?

thanks

wynneit · ‎09-17-2008

I notice you are a CCIE so really do not want to be teaching you to suck eggs! however it is interesting. What is the client testing etc.

Remember the WLAN is a collision domain and it may be just due to collisions in the contentious physical layer? Random backoff etc?

RICHARD MESSINGER · ‎09-17-2008

I am looking for the odd duck thing that I may have over looked. In this customer environment, there are no other devices on the wireless lan to provide collisions. And colisions would be more random than every 60 seconds.

He has seen this behavior with several different access points from different manufacturers, not just his Cisco AP's so thinking that there is something else that I am missing.

Have had my CCIE for a long time and there is just so much to know and remember that sometimes I am not sure I ahve enough brain cells left.

wynneit · ‎09-17-2008

Messinger I know I am rwstarting my certs but aiming for CCIE Wireless and R&S. Can you post configs etc and what device is connecting. There are auth timeouts but cant recall where they are exacly also I believe if you are using windows client zero config it scans every 60 seconds for other networks that may cause a delay. Also try changing the authentication/security see if anything changes like the delay or duration/timing

RICHARD MESSINGER · ‎09-17-2008

If I can get my hands on the config, I will check out your suggestions. But you may have hit on the problem with the client doing the scanning.

Thanks.