Troubleshooting

Once you have learned the fundamentals of routing and bridging and begin to implement them in your network, it is almost inevitable that you will encounter a situation where you need to employ your troubleshooting skills. In this section, we will consider how to troubleshoot both routing and bridging.

The pfSense routing table, which can be found by navigating to Diagnostics | Routes, is a good starting point for learning about which routes exist, how they are configured, and the number of times a route has been used. The table is divided into two sections, one for IPv4 routes and the other for IPv6 routes. Each entry in the table has several columns: Destination is the route's destination, Gateway is the gateway through which the route travels, Use is the number of times the route has been used, Mtu is the maximum transmission unit, Netif is the gateway's interface, and Expire tells us if the route has expired (which may be the case for a temporary route such as an ICMP redirect...