Ports randomly drop on 3348 and 3324 that are connected to 5324
I have an issue that started several months ago. First I will say that for the last 3 years the switches have had no issues and worked fine.
I have an upstairs and downstairs in our office. All servers are down stairs with serveral users, the rest are upstairs.
Downstairs I have a 5324 with a LAG on 4 ports going to the 5324 Upstairs. Also on the 5324 upstairs I have two more Lags both with 2 ports. Lag 2 goes from the 5324 upstairs to a 3348 and Lag 3 goes from the 5324 upstairs to a 3324.
Randomly throughout the day users would complain they were kicked out of exchange, or kicked off the internet. They simply logged back in and everything was fine. I went thru the Ram log files and could see on the Upstairs 5324 that my Lags 2 and 3 which went to the 3348 and 3324 would drop and then instantly reconnect. However the Lag 1 that went downstairs to the other 5324 never had an issue. Some days no issues, other days it would drop 3-5 times.
I believe it to be a bad switch upstairs (5324) so I switched it out with the same model downstairs. I also removed Lag 2 and Lag 3 and simple have one cable from the Upstairs 5324 to the 3348 and one cable from the 5324 to the 3324.
Guess what, its is still happening. So I know its not the 5324 switch. And now instead of the Lag 2 and 3 going down, I see the ports that connect the 3324 and 3348 go down and come back up.
What is more confusing is why do both 3348 and 3324 go down together. I seriously need help in determining what to do next.