The route priority is also referred to as the "managed distance" of the route in some documents, and is a positive integer, range 0~255, which is used to specify the priority of the routing protocol. Multiple routing protocols can be run on a single router at the same time. Different routing protocols have their own standards to measure the quality of the routes, and each routing protocol sends its best route to the routing table. This reaches a similar destination address, which may be different routes that are learned by multiple routes by different routing protocols. Although each routing protocol has its own metrics, the metric values between the different protocols have different meanings and are not comparable. The router must choose the best path computed by one of the routing protocols to join the routing table as a forwarding path. In the actual application, the router chooses the routing protocol based on the route priority. Assigning different routing priorities to different routing protocols is a high priority for small values. When there are multiple routes to the same destination address, you can select one of the priority values as the optimal route based on the priority size, and write the route into the routing table.
| Route type |
Route Priority |
| Direct |
0 |
| STATIC EIGRP |
1 90 |
| OSPF ISIS |
110 115 |
| RIPV1, V2 |
120 |
| IBGP |
200 |
| Special |
255 |
The route priority assignment principle is that direct-attached routes have the highest priority. Manually set route entries take precedence over dynamically learned routing entries. The complex routing protocol of the measure algorithm takes precedence over the simple routing protocol of the measure algorithm. For example, both the OSPF routing protocol and the RIP routing protocol find a route to the same destination, because OSPF has a priority of 110 higher than RIP's priority 120, and the router will prioritize the routes discovered by the OSPF protocol and put it in the routing table. It is important to note that the definitions between different vendors may not be the same, but the priority of the various routing protocols can be modified manually by the user through specific commands (the priority of the direct-attached route cannot be modified in general).
