IP route table

The IP route table contains paths to IP destinations.

The IP route table can receive the paths from the following sources:

• A directly-connected destination, which means there are no router hops to the destination
• A static IP route, which is a user-configured route
• A route learned through RIP
• A route learned through OSPF
• A route learned through BGP4

The IP route table contains the best path to a destination:

• When the software receives paths from more than one of the sources listed above, the software compares the administrative distance of each path and selects the path with the lowest administrative distance. The administrative distance is a protocol-independent value from 1 through 255.
• When the software receives two or more best paths to a destination and the paths have the same metric (cost), the software can load share traffic among the paths based on destination host or network address (based on the configuration and the Layer 3 device model).

Here is an example of an entry in the IP route table.

Destination       NetMask           Gateway           Port   Cost   Type
10.1.0.0          255.255.0.0       10.1.1.2          1/1/1    2      R

Each IP route table entry contains the destination IP address and subnet mask and the IP address of the next-hop router interface to the destination. Each entry also indicates the port attached to the destination or the next-hop to the destination, the route IP metric (cost), and the type. The type indicates how the IP route table received the route.