Precedence of external routes imported by OSPF on S series switches

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When an S series switch runs OSPF, you can run the import-route command in the OSPF process view to import external routes. The routes imported using this method are OSPF ASE routes and default precedence is 150.

Other related questions:
External routes imported using OSPF on a CE series switch cannot be viewed in the routing table
This problem is caused by routing loop detection. By default, routing loop detection is enabled on a CE series switch. When OSPF VPN multi-instance is deployed on a Multi-VPN-Instance CE (MCE) device, and DN Bit is set in Type 3, Type 5, or Type 7 LSAs, corresponding routes cannot be calculated and viewed in the routing table because routing loop detection is performed during OSPF route calculation. To address this problem, run the vpn-instance-capability simple command on the MCE device to disable routing loop detection of the OSPF instance.

Why imported external routes are not displayed in the LSDB on an S series switch
Perform the following operations on the S series switch to solve the problem. Run the display ospf interface command to check whether the interface that imports external routes is in the Up state. Run the display ospf brief command to check whether the device that imports external routes belongs to the stub area. Check whether the neighbor status is Full if external routes are learned from a neighbor. Check whether the lsdb-overflow-limit command is configured, and whether the total number of external routes exceeds the maximum limit. Check whether the asbr-summary command is configured to aggregate external routes.

Set the maximum number of routes imported by OSPF on S series switches
On S series switches, when the number of external LSAs (Type 5 and Type 7 LSAs) imported by OSPF exceeds the limit allowed by overflow, the excessive external LSAs cannot be processed properly and are discarded. To address the problem, run the lsdb-overflow-limit command in the OSPF process view to set the maximum of external LSAs in an LSDB. By default, the maximum number of external LSAs in the LSDB is not set. For example, set the maximum number of external LSAs in an LSDB to 400000 as follows: [HUAWEI] ospf 100 [HUAWEI-ospf-100] lsdb-overflow-limit 400000

USG2000 / 5000 Configure OSPF to import external routes
USG2000 & 5000 Configure OSPF to import external routes as follows: 1. Configure the basic parameters of each interface to implement interworking. 2. Configure OSPF on the USG. 3. Configure the OSPF area on the USG and add the Internet segment on the USG to the OSPF area. 4. Configure OSPF to import direct routes on the egress gateway.

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