Routers are the devices responsible for ensuring that traffic goes to the right network segment. Unlike switches that operate at Layer 2, routers work at Layer 3, directing traffic based on TCP/IP address and protocol (port number). Routers are responsible for particular Layer 3 address spaces and manage traffic using information in routing tables and configured policies. Routers exchange information and update their forwarding tables using dynamic routing protocols.
Network engineers use router logs and statistics to monitor traffic flow and ensure that traffic is being correctly forwarded between network segments. Data from routing protocol updates can show whether your routers are appropriately exchanging route tables with other locations, that external traffic can reach you, and that internal traffic is correctly forwarded to external routers. Router data can also be used to detect configuration changes and error or failure alerts correlating with security indicators.