Why is an OSPF route on an S series switch in the Invalid Adv state

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Question: Why is an OSPF route in the Invalid Adv state?

Answer: After you run the display ip routing-table x.x.x.x verbose command on an S series switch supporting OSPF to check information about a specified route, you may find that Invalid Adv is displayed in the State field. Possible causes are as follows:
A route with a smaller preference value, for example, a directly connected route, exists.
The route is filtered out based on a filter policy.
A sham link is configured on the outbound interface.

Other related questions:
Why are routes in the OSPF routing table on an S series switch in the inactive state
A policy that filters all OSPF routes may be configured in an OSPF process. As a result, all routes in the OSPF routing table are in the inactive state.

Routes imported into IS-IS are invalid on S series switches
Q: Why are routes imported into IS-IS invalid? A: For S series switches supporting IS-IS, if the IS-IS level is not set when routes are imported into IS-IS, level-2 IS-IS is used by default. That is, routes are imported into level-2 IS-IS. To import routes to areas of other levels, specify the area level.

Why is an OSPF-enabled interface on an S series switch in different states
Question: Why is an OSPF-enabled interface in different states? Answer: If a tunnel interface is created using the IP address of an OSPF-enabled loopback interface and the tunnel interface is Down, the interface is in different states. You can run the display ospf interface all command to check details about an OSPF interface. [HUAWEI]display ospf interface all OSPF Process 1 with Router ID 1.1.1.1 Interfaces Area: 0.0.0.0 (MPLS TE not enabled) Interface: 1.1.1.1 (LoopBack0) Cost: 1 State: DR Type: Broadcast MTU: 1500 Priority: 1 Designated Router: 1.1.1.1 Backup Designated Router: 0.0.0.0 Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1 Interface: 1.1.1.1 (Tunnel0/0/1) Cost: 1562 State: Down Type: P2P MTU: 1500 Unnumbered Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1

Why configure OSPF route tag on S series switches
For S series switches supporting OSPF, the OSPF router tag is applied to VPNs and prevents loops of Type 5 LSAs in CE dual-homing networking. If the tag of a received Type 5 LSA is the same as the router tag of OSPF on a PE, the PE neglects this LSA when calculating routes. When a CE is connected to two PEs, PE1 generates a Type 5 LSA based on the imported BGP route and sends the LSA to the CE, and the CE forwards the LSA to PE2. The OSPF route takes precedence over the BGP route, so PE2 replaces the BGP route with the OSPF route. As a result, a loop occurs. If the route tag is configured on a PE, when the PE receives an LSA with the same route tag as its own route tag, it neglects this LSA, avoiding loops. By default, the route tag is calculated using the BGP AS number. If BGP is not configured, the route tag is 0. In OSPF public network instances, router tags cannot be used to prevent loops but can be used as a filtering condition in a policy. When setting the router tag of ASE-LSAs and NSSA-LSAs, not the following: The route-tag command is used in the OSPF multi-instance scenario. The default tag command is used in the OSPF public network instance scenario. The import-route tag command can be used in either of the preceding scenarios.

Under what conditions is the status of OSPF set to invalid adv
display ip routing-table 10.11.11.11 verbose Routing Table : Public Summary Count : 2 Destination: 10.11.11.11/32 Protocol: OSPF Process ID: 588 Preference: 10 Cost: 22 NextHop: 10.1.200.2 Interface: Vlanif10 RelayNextHop: 0.0.0.0 Neighbour: 0.0.0.0 Label: NULL Tunnel ID: 0x0 SecTunnel ID: 0x0 BkNextHop: 0.0.0.0 BkInterface: BkLabel: 0 Tunnel ID: 0x0 SecTunnel ID: 0x0 State: Invalid Adv Age: 00h57m42s Tag: 0 Destination: 10.11.11.11/32 Protocol: ISIS Process ID: 46435 Preference: 15 Cost: 10 NextHop: 172.16.234.18 Interface: Vlanif20 RelayNextHop: 0.0.0.0 Neighbour: 0.0.0.0 Label: NULL Tunnel ID: 0x83810BD5 SecTunnel ID: 0x0 BkNextHop: 0.0.0.0 BkInterface: BkLabel: 0 Tunnel ID: 0x0 SecTunnel ID: 0x0 State: Active Adv Age: 15h13m42s Tag: 0 In the preceding command output information, the state field is set to Invalid Adv because: A route, such as a direct route, with a smaller preference, exists. The route is filtered out by the filter policy. The output interface is on a sham link.

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