Our customer is experiencing intermitent high latency on the MU while pinging the gateway or the AAP ip address. Normal latency is usually about 2ms to 7ms then after 4 to 5 seconds will increase to 100ms to as high as 1.2 seconds then back again to normal. There are no other MU's connected on the AAP. This does not happen if a user is on the wired side pinging the same gateway or AAP with a 1ms or less latency. I captured the wireless packets in parallel with the ping test and saw lots of ARP broadcast in normal and high latency situations. I then captured the syslogs on the AAP5131 (ADP2.5 version) and I noticed that everytime I see the message below, an increase in latency occurs. Aug 27 20:17:45 10.101.21.204 wispctld: main : select() timed out Aug 27 20:17:45 10.101.21.204 wispctld: Wisper_Event : WISPER_STATE_RUN to WISPER_STATE_RUN, evt=WISPER_EVENT_TIMEOUT tmo=1 Aug 27 20:17:45 10.101.21.204 wispctld: Wisper_Event : Timer_Reg_Callback Aug 27 20:17:46 10.101.21.204 wispctld: main : select() timed out Aug 27 20:17:46 10.101.21.204 wispctld: main : select() timed out Aug 27 20:17:46 10.101.21.204 wispctld: Wisper_Event : WISPER_STATE_RUN to WISPER_STATE_RUN, evt=WISPER_EVENT_TIMEOUT tmo=1 Aug 27 20:17:46 10.101.21.204 wispctld: Wisper_Event : Timer_Reg_Callback Aug 27 20:17:47 10.101.21.204 wispctld: main : select() timed out Any idea what is causing this timeout and how can we mitigate the problem. Any help is appreciated.
AAP5131 intermitent high latency// Expert user has replied. |
4 Replies
As just said, try changing terminal's profile to CAM mode and see how pings behave then. By the way, CAM mode uses quite a lot of battery, so you would better not set it "as a fix". This is just to check that the "issue" is not such.
This happens on all AAP's within the same subnet, there are no interferences via AD Mobile and the SNR is 25 and above. Tried to covert my wireless client configuration from PSP to CAM, confirmed client CAM status via the RFS7000, still the same high latency problem. Converted AAP to stand alone AP - connected by Lan port - still the same Converted AAP to stand alone AP - connected by Wan port - high latency gone. Already opened a ticket to CIC. Thank you very much with your help.
The log - has nothing to do with ping latency. Interference on the air - can cause latency. To determine more precisely - one needs to look at your traces. Open a case with Tier II and provide them all the info that you have - AP config, log, traces and relevant MACs. Alona
Arnold If this is PSP MU.What you are seeing is normal. A PSP client will suspend the radio for short periods of time while associated to conserve battery life. Ping times will seem to go in a cycle, starting low and climbing in response time and then drop and start over. Try doing a ping test whit the client set for CAM mode and you will see consistant ping times of around 4ms.