#251 - Schneider How to Troubleshoot a Network Issue

- Export the following files from the Managed Switch:

> audittrail.htm: it summarizes the statys and major events in the switch, such as power cycle, firmware versions, configuration updates.

> running-config.cli: it is a dump of the running configuration file. Check the ports that are set-up for vlan tagging (main-ring) and (spanning-tree (sub-ring) along with their redundant-coupling port configuration.

> systemlog.htm: it logs system events that are useful for troubleshooting such as: Severity threshold for high priority buffer
Frequent new Route Bridge changes Frequent STP issues such as port state changing from forwarding to discarding

The cause of the problems may be electrical or software. For further analysis it is helpful to connect to the switch on a port which duplicates the suspected ports and run a Wireshark scan.
Filter example: !(udp.port == 2222) and not arp and not ip.addr == 192.168.x.240

In wireshark, add a delta time column: Edit > Preferences > Appearance > Columns > Add column and select Delta Time

Example of Spanning -Tree issues related to a misconfiguration of the Managed Switch:

Example of connection resets (e.g., crash or watchdog reset): tcp.flags.reset == 1

Example of retransmissions (e.g., signal network congestion or device unresponsiveness): tcp.analysis.retransmission

Example of device overload (e.g., PLC overload): tcp.analysis.zero_window