I support many medium to large networks, using primarily Netgear gigabit smart switches and Sonicwall routers. I have a few locations right now that are experiencing intermittent network issues, where pings from a local server to the gateway will be more (sometimes significantly more) than <1ms. Also pings to 8.8.8.8 will jump up to a few hundred ms. On another network, randomly (only between 6am and 12am) will the static IP of the sonicwall completely stop responding for 5-20 seconds at a time, but the gateway (comcast coax modem) is just fine.
Which leads me to believe in both of these instances that there is a single device on the network causing some sort of packet storm which is affecting the whole network. In the past, when I have a network consistently doing something like this, I have a tech start pulling wires out of the switch one by one until we determine which device is causing the issues. But when it's intermittent and only lasts < 20 seconds at a time, this is impossible.
Does anyone have recommendations for what tool or software etc. to use to diagnose such a connection/network issue.
I would greatly appreciate whatever advice I can get.
Thanks