We've got a strange problem we've been troubleshooting for weeks with Cisco 2960G switches, Cisco 2950 and also Cisco 2940, no matter what release of IOS we are using. Our application runs under the QNX OS, 6.4.1, with Intel Pro 1000 adapters in every systems.
Let's say we start with a small 8 ports Cisco 2940 switch, which has a Gigabit port.
We have 4 systems in the 100 mbps ports, and one "receiver host" in the Gigabit port. The 4 systems are sending a lot of data to the 'Gigabit receiver host', the gigabit port seems to be occupied at around 15%.
With that being said, on the TCP/IP level, we are losing some packets like they were never transferred, and if I do a "show int gi0/1" the only error counters I see increasing steadily are the "no buffer" and the "ignored". They are increasing like a dozen every second while our application is running, and are not increasing when it's not. No other error, no duplex problem or anything. Tests are done in an isolated environment with no other workstations or network noise.
We contacted QNX and they told us the "swich" was the problem. At first we didn't believed them and they demonstrated us with a basic 3COM switch, there were no packet loss at all.
They also told us that Cisco might cause the problem with the PFC (Priority Flow Control). With this information, we tried to disable the "flowcontrol" in and out, on every GigE ports, but still, the problem remains.
Could the 'PFC' really be the problem, where should I look at ? Can I disable the PFC ?
Thanks a lot,