Currently running Software pack 7.1.0-EA .
Noticed a wierd situation when a user transfered a large file form his wireless laptop to a wired PC on the same vlan (Vlan1). A call was also in progress at the same time and the audio quality immediately became poor with words being repeated and sounding choopy and eventually dropping the call altogether. Users who were doing anything data related saw a real slowdown in speed and unable to browse the network or internet at some points.
Took a little while to figure out what was going on, but eventually narrowed it down to the tranfer of a specifi file from a specific user. We were able to replicate this problem easily.
Here are the details:
- When transfering a 577MB ZIP file from a laptop on the Wireless LAN (Vlan1 WPA encryption) to a Wired PC on VLAN 1, the CPU on the UC520 spiked to 100% until the transfer finished. When the CPU spiked, IP phones had up to 5 second lag betweeen picking up handset and getting dial tone, 5 second lag between pressing a button and recieving a response, call quality completly going out the window and sometimes even unregistering the phone. (Terminal Montor showed the phones unregistering abnormally)
- When going wired Laptop to wired PC with the same file, the CPU never spiked at all and every thing remained normal.
- When going Wired PC to Wireless Laptop with the same file, the CPU spiked the same, exactly as in scenario 1.
- When trying the same file transfer scenario (Scenario 1) with a laptop that had a Wirelss B card to a Wired PC, the CPU only spiked to 40% and everything continued to function just fine.
Screen shot below?