Use distribute-list to filter OSPF route information

In a large network, when a router publishes and receives route information, it may need to implement some policies to filter route information. For example, it only receives or releases route information that meets certain conditions. In this case, we need to use distribute-list to filter route information. Distribute-list also implements the routing control function by calling access-list (access Control list. However, unlike access-list on interfaces, distribute-list only filters route information and does not limit the data actually forwarded on the network. The following is an example of how to use distribute-list to filter OSPF route information.

 
 
 
 
I. networking structure and requirements
One company has one branch in Beijing, Shanghai and Guangzhou, And the routers of the three companies all run the OSPF routing protocol. The network extension diagram is as follows:
Beijing company CIDR Block: 10.10.10.0/24;
Shanghai company CIDR Block: 10.10.20.0/24 (Finance Office), 172.16.10.0/24 (office)
The CIDR Block of the Guangzhou Company is 10.10.30.0/24 (Finance Office) and 172.16.20.0/24 (office)
The requirements are as follows:
1. Beijing company receives all routing information in the OSPF network.
2. Shanghai only receives route information from Beijing (10.10.10.0/24) and Guangzhou Office (172.16.20.0/24.
3. Guangzhou only receives route information from Beijing (10.10.10.0/24) and Shanghai Office (172.16.10.0/24.

Author "rice field circle"