The BEST way is to use a network tester like a Fluke Linkrunner AT-2000 or a DSP-5000 or a Cable certifier with BERT testing capability or network sniffing capability. If you don't have or can't obtain these testing devices, then using your laptop, follow this very simple tutorial
Click Here and pay special attention to packet loss and jitter. When the ESI-Link fails or has delay problems is can be narrowed down to packet loss and/or jitter. If you get packet loss or jitter, then you need to address the source which may be the switches. Just because the Cisco switch is a gigabit switch, don't rule it out. I fought with one for a week that had weird packet distortion. To test it, go to an office supply store or Best Buy and purcahse a gigabit Netgear, Linksys or similar cheap router and see if that resolves the problem.
Rcaman
