Switch: Dell PowerConnect 2848
Wireless AP: Cisco 1140 Series
Laptops: Dell E6510,E6400 running Win7 Enterprise
Symptom: Devices connected via wireless fail to ping machines that are hard wired for generally 5 attempts, and then work perfectly. Doing a ping -t will show near perfect results (0% loss) for hours after the initial failures.
Wired devices fail to EVER ping a wireless device with "destination host unreachable" UNLESS I ping it with the wireless device first. Basically the wired devices are unable to ARP for a wireless device.
If I ping with the wireless device, it gets added to the arp table on the wired device, and then the wired can ping the wireless. If I delete the arp table entry from the wired device, it goes back to "destination host unreachable".
I have replicated this on W2K8 and Ubuntu Linux wired servers, and multiple Win7 laptops connected wirelessly. If I disable the wireless NIC, and hard wire the laptops, everything is fine.
Client ARP caching is set to disabled on the Cisco AP's.