On Fri, 2010-08-13 at 06:48 -0600, Mark Dueck wrote:
> It's a brand new PS purchased about 2 months ago.
>
> I'll have to try B only then to see if that will have better
> performance.
>
> I've been checking all the clients, and I see some of them with very
> high retries. They are pushing through trees. Could be a likely
> cause right?
Excessive retries can definitely cause a severe reduction in throughput.
Here's a study I did a year or two ago. The test was to see how many
retries a typical 802.11 AP/station would send before giving up. I was
surprised. This particular test run was to see how effective MikroTik's
frame lifetime setting was.
Static test configuration 2
* AP, 802.11b, channel 1, ROS 3.3
* Engenius station
* RB112 w/ NMP-8602 station, ROS 3.3
* RB112 w/ NMP-xxxx sniffer, ROS 3.3
Test run 2.1
* Dynamic test configuration
o AP, 802.11b, channel 1
+ hw-retries - 4
+ on-retry-fail-time - 100ms
+ disconnect-timeout - 3s
+ frame-lifetime - 0 (infinite)
* Results
o Max observed frame retry count - 185
Test run 2.2
* Dynamic test configuration
o AP, 802.11b, channel 1
+ hw-retries - 0
+ on-retry-fail-time - 100ms
+ disconnect-timeout - 3s
+ frame-lifetime - 0 (infinite)
* Results
o Max observed frame retry count - 76
Test run 2.3
* Dynamic test configuration
o AP, 802.11b, channel 1
+ hw-retries - 0
+ on-retry-fail-time - 100ms
+ disconnect-timeout - 3s
+ frame-lifetime - 10cs (100ms)
* Results
o Max observed frame retry count - 7
Test run 2.4
* Dynamic test configuration
o AP, 802.11b, channel 1
+ hw-retries - 0
+ on-retry-fail-time - 100ms
+ disconnect-timeout - 3s
+ frame-lifetime - 1cs (10ms)
* Results
o Max observed frame retry count - 4 (1x11Mbps, 1x5.5Mbps,
1x2Mbps, 1x1Mbps)
Test run 2.5
* Dynamic test configuration
o AP, 802.11b, channel 1
+ hw-retries - 4
+ on-retry-fail-time - 100ms
+ disconnect-timeout - 3s
+ frame-lifetime - 1cs (10ms)
* Results
o Max observed frame retry count - 4 (4x11Mbps)
These tests are counting AP-side retransmits, but the same applies to
the CPE. When we have a suspect client with a MikroTik CPE, we login
and change frame lifetime to ~10. If it completely breaks them, then we
know they're (part of) the problem. In an extreme case, we had to put
another AP up in sniffer mode to find the culprit. In more than one
case, the problem was a metal barn either directly in front of the
customer's antenna, or at the half way point.
HTH,
-Kristian
--------------------------------------------------------------------------------
WISPA Wants You! Join today!
http://signup.wispa.org/
--------------------------------------------------------------------------------
WISPA Wireless List: [email protected]
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
