1. A network switch comprising: a plurality of first ports to communicate with a corresponding plurality of computer systems; a second port to communicate with an information network; a computer processor; logic instructions on non-transitory computer readable storage media executable to cause the computer processor to: periodically determine whether there is a connectivity problem with at least one of the first ports and the second port independently of responding to requests from the computer systems; if one of the first ports and the second port is determined to have a connectivity problem, generate information including an error message; receive, from one of the computer systems, a request directed to the port having the connectivity problem; in response to receipt of the request directed to the port having the connectivity problem, intercept the request using an access control list (ACL) to detect requests using a specified communication protocol and transmit the error message to the computer system from which the request is received; and clear the error message when the connectivity problem is no longer detected.