The question describes a scenario where a network event is causing all communication to stop, and the network administrator can only access the switch using the serial console port, not SSH.
This suggests that the problem is related to the network layer or below, as SSH operates at the application layer and requires network connectivity to function.
The port statistics show a huge discrepancy between the total receive and transmit rates, as well as the unicast and broadcast/multicast packets per second. This indicates that there is a lot of traffic being generated and forwarded within the network, but not reaching the intended destinations.
The most likely cause of this excessive traffic is a switch loop, which occurs when there are multiple paths between switches that create a circular flow of data. Switch loops can cause broadcast storms, MAC address table instability, and network congestion, leading to network outages.
To verify this, the network administrator should use a tool such as Spanning Tree Protocol (STP), which is designed to prevent and detect switch loops by blocking redundant links and electing a root bridge. STP can also provide information about the topology and status of the network, such as the root port, designated port, and blocked port for each switch. Reference:
CompTIA Network+ N10-008 Study Guide, Chapter 2, Section 2.3, Switching Technologies, page 741 Professor Messer's CompTIA N10-008 Network+ Course Notes, Section 2.3, Switching Technologies, page 132 Professor Messer's CompTIA N10-008 Network+ Training Course, Video 2.3 - Switching Technologies, 12:00 - 14:003