Directly connected routes and Local routes

Directly connected and local routes are the routes the router automatically adds to the routing table. Routers derive these routes from the IP configuration you make on their interfaces.

Suppose you configure the IP address 20.0.0.1 on GigabitEthernet 0/1 of a router. The router will add two routes from this IP configuration. LAN segments use the router's interface as the default gateway. Because of this, the router automatically assumes that the IP address you configure on an interface will serve as the default gateway IP for the LAN segment connected to that interface. The IP address 20.0.0.1 belongs to the network 20.0.0.0/8. Hence, the router assumes that the GigabitEthernet0/1 interface is connected to the network 20.0.0.0/8 and adds a directly connected route for it in the routing table.

Routers support remote connections. A remote connection needs an IP configuration on both the remote and the client devices. You can use the interfaces' IP configurations to open remote connections with routers. For example, you assigned the IP address 20.0.0.1 to GigabitEthernet0/1. You can use it to access the router remotely. When a router receives a data packet for the IP address configured on one of its interfaces, instead of forwarding it, it processes it for internal functions, such as a ping request or a remote connection.

Key points:-

• Routers automatically learn the directly connected and local routes from the IP configuration you assign to their interfaces.
• Routers use directly connected routes to reach networks connected to their interfaces.
• Routers use the local routes to reach their interfaces.
• Local routes are also known as host routes.
• Routers add the directly connected and local routes from the IP configuration assigned only on the up interfaces.
• If an interface is down, the router does not add the directly connected and local routes for the IP configuration assigned to it.
• Routers automatically manage directly connected and local routes based on interface state.
• If you shut down an interface, the router automatically removes the directly connected and local routes related to it.
• The directly connected and local routes have the AD value 0.
• An AD value is the trustworthiness of the route.
• If multiple routes for the same destination exist, the router selects the route with the lowest AD value.
• Routers use the letter C to indicate a directly connected route in the routing table. To indicate a local route, they use the letter L.

Conclusion

A router adds two routes from its interfaces' IP configuration. These routes are local routes and directly connected routes. A local route represents the interface. A directly connected route indicates the network to which the interface is connected. The router uses the local route to accept a remote connection and a directly connected route to forward the incoming packets to the local network connected to the interface.