Directly connected and local routes are the routes the router automatically adds to the routing table. Routers derive these routes from the IP configuration we make on interfaces.
Let us take an example.
Suppose you configure the IP address 20.0.0.1 on GigbitEthernet 0/1. The router will add two routes from this IP configuration. We use the router's interface as the default gateway. Because of this, the router automatically assumes that the IP we configure on an interface will work as the default gateway IP for the network connected to the interface. The IP address 20.0.0.1 belongs to the network 20.0.0.0/8. Hence, the router assumes the network 20.0.0.0/8 is connected to the GigabitEthernet and adds a directly connected route for the network 20.0.0.0/8 in the routing table.
Routers support remote connections. A remote connection needs an IP configuration on both the remote and the client devices. We can use interfaces' IP configurations to open remote connections with routers.
For example, we assigned the IP address 20.0.0.1 on GigabitEthernet0/1. We 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, the router processes it for internal functions such as a ping request, remote connection, etc.
This tutorial is part of the tutorial series "Understanding route types in the routing table.". Other parts of this series are the following.
Chapter 1 The show IP route command on Routers
Chapter 2 Routing table updating methods
Chapter 3 Directly connected routes and Local routes
Chapter 4 Static and Floating Static Routes Explained
Chapter 5 Static and Dynamic routes in the routing table
Chapter 6 Default Route in the Routing Table
Chapter 7 Network Routes and Host Routes Explained
Key points:-
- Routers automatically learn the directly connected and local routes from the IP configuration we assign to the interfaces.
- Routers use the directly connected routes to reach the network connected to the interfaces.
- Routers use the local routes to reach the 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 the directly connected and local routes from the state of interfaces.
- If we 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 having 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.
