Begin by looking at the power and LED lights on your network switch. Make sure all cables are plugged in tight. Turn your switch off and then on to fix errors. This helps you find what is. If i connect any Pc or device to core witch port i cannot ping it, I have first enable the ICMP stream in the device firewall or windows firewall. After lots of troubleshooting, I'm unable to get the port Gi1/0/1 up, it's always in the state down/down (notconnect). Site B also has the exact same setup and LAN equipment. A network switch failure can disrupt business operations by causing connectivity issues, packet loss, and downtime for connected devices. 1D standard, this made the network unavailable for extended periods—tens of seconds—during configuration.