We have replaced a Cisco network in a warehouse and plastics factory with a ZD1100 and a combination of ZF7892 and ZF7372. We are running into connectivity issues for the handhelds (Intermec CK31) devices.
The handhelds run a telnet based application.
If we ping -t from the server to the access points we get excellent response times. When we do the same out to the handhelds we mostly get excellent response times in the 2 - 5 ms range. However we also get a few spurious times in the 20, 50 or couple hundred ms range. We also get an occasional set of 2 or 3 pings that time out.
The ZD is handling all the channel assignments. We do have 2 other 'rogue' access points in the environment but they are not in channel conflict.
Is there a best practices guide for configuring a warehouse?
Is ping -t a valid test of continuity? If not, what to use?
Ultimately, the end user's session freezes on the CK31. Sometimes after a wait the session recovers. Sometimes that wait causes the handheld to lock up. We can mess with the keep-alive timer but that just seems like a work around for inconsistent connectivity.
I've worked a number of Intermec scanner cases. Like VoIP, telnet based apps
are very time sensitive, have problems with dropped/lost packets, etc. You may
find that WPA2-PSK (use AES, not auto) works best if you do roam between APs
with L2 cached credentials. You might also disable background scanning after
your APs are on assumed best channels, as channel changes also disrupt telnet
applications. Run the latest ZD firmware 22.214.171.124.15, and open a ticket with support
if you need deeper troubleshooting. Latest firmware/drivers on Intmec are equally
as important, as I don't think you should have occasional ping timeouts.
Thanks Michael. I did open a case today and we started by upgrading to 126.96.36.199.9 to get past a known issue in the original version. The issue was described as a "Loop detected" error that results in a wireless client being disconnected from the network for 10 second.
I will keep your suggestions in mind as we move forward. Once issue that may be problematic is that the CK31 device can only use WEP for encryption. No WPA or WPA2.
Until the upgrade, there was little activity in the logs suggestion that the ZD was changing channels on the APs. Having restarted because of the upgrade, I do see things bouncing around a bit. Hopefully that quiets down as thing get organized.
I am not convinced we are out of the woods just yet as I have seen a couple spurious "Not Available" messages coming from my continuous pings out to a few handhelds.
We will let the upgrade settle in over night and review the user experience in the morning. So far after about an hour of run time on the new release we have not heard any user complaints so that is good. Especial;ly in light of what I have seen with the PING utility.