# US 12,003,412 B2 · Method and apparatus for processing link state information > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,412 B2 - Document ID: US12003412B2 - Status: Granted - Kind: B2 - Application number: 17/650,688 - Filed: 2022-02-11 - Published: 2022-05-26 - Granted: 2024-06-04 - Earliest claimed: 2019-08-14 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Yongzhe Su - Web page: https://patentgrep.com/patent/US12003412B2 ## CPC - H04L 45/02: Topology update or discovery - H04L 45/28: using route fault recovery - H04L 45/03: by updating link state protocols - H04L 45/122: by minimising distances, e.g. by selecting a route with minimum of number of hops - H04L 45/22: {Alternate routing} - H04L 45/74: Address processing for routing - H04L 47/28: in relation to timing considerations - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method and an apparatus for processing link state information is provided. A first network device receives first link state information sent by a second network device, where the first link state information is link state information of a third network device; in response to receiving the first link state information, the first network device deletes second link state information that is received by the first network device from the second network device, where the second link state information carries a segment identifier of the third network device; and the first network device deletes, based on the first link state information, third link state information received from the second network device, where the third link state information carries information for computing a route to the third network device. ## Claims ### Claim 1 A method, comprising: receiving, by a first network device, second link state information from a second network device, wherein the second link state information carries a segment identifier of a third network device; in response to receiving the second link state information, recording, by the first network device, a forwarding entry associated with the third network device in a forwarding table; receiving, by the first network device, third link state information from the second network device, wherein the third link state information carries information for computing a route to the third network device; in response to receiving the third link state information, recording, by the first network device, the route to the third network device in a routing table; receiving, by the first network device, first link state information sent by the second network device, wherein the first link state information is link state information of the third network device; in response to receiving the first link state information, deleting, by the first network device, the second link state information, wherein the forwarding entry associated with the third network device is deleted from the forwarding table when the second link state information is deleted; and deleting, by the first network device based on the first link state information, the third link state information, wherein the route to the third network device is deleted from the routing table when the first link state information is deleted. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first link state information carries an indication identifier, and the indication identifier indicates to a network device that receives the first link state information to delete the third link state information. ### Claim 3 (depends on 2) The method according to claim 2, wherein deleting, by the first network device based on the first link state information, the third link state information received from the second network device comprises: deleting the third link state information in response to the first network device determining that the first link state information carries the indication identifier. ### Claim 4 (depends on 2) The method according to claim 2, wherein the first link state information is carried in a link-state advertisement (LSA) defined according to an open shortest path first (OSPF) protocol, and the indication identifier is carried in an options field in a packet header of the LSA. ### Claim 5 (depends on 1) The method according to claim 1, wherein the first network device is a cell site gateway (CSG) and the second network device is an aggregation site gateway (ASG). ### Claim 6 A first network device, comprising at least one processor; and one or more memories coupled to the at least one processor and storing instructions for execution by the at least one processor, the instructions comprising instructions that instruct the at least one processor to cause the first network device to: receive second link state information from a second network device, wherein the second link state information carries a segment identifier of a third network device; in response to receiving the second link state information, record a forwarding entry associated with the third network device in a forwarding table; receive third link state information from the second network device, wherein the third link state information carries information for computing a route to the third network device; in response to receiving the third link state information, record the route to the third network device in a routing table; receive first link state information sent by the second network device, wherein the first link state information is link state information of the third network device; in response to receiving the first link state information, delete the second link state information, wherein the forwarding entry associated with the third network device is deleted from the forwarding table when the second link state information is deleted; and delete, based on the first link state information, the third link state information, wherein the route to the third network device is deleted from the routing table when the first link state information is deleted. ### Claim 7 (depends on 6) The first network device according to claim 6, wherein the first link state information carries an indication identifier, and the indication identifier indicates to a network device that receives the first link state information to delete the third link state information. ### Claim 8 (depends on 7) The first network device according to claim 7, wherein the instructions further comprise instructions that instruct the at least one processor to cause the first network device to: delete the third link state information in response to determining that the first link state information carries the indication identifier. ### Claim 9 (depends on 7) The first network device according to claim 7, wherein the first link state information is carried in a link-state advertisement (LSA) defined according to an open shortest path first (OSPF) protocol, and the indication identifier is carried in an options field in a packet header of the LSA. ### Claim 10 (depends on 6) The first network device according to claim 6, wherein the first network device is a cell site gateway (CSG) and the second network device is an aggregation site gateway (ASG). ### Claim 11 A non-transitory computer readable storage medium storing instructions by at least one processor, the instructions including instructions for: receiving second link state information from a second network device, wherein the second link state information carries a segment identifier of a third network device; in response to receiving the second link state information, recording a forwarding entry associated with the third network device in a forwarding table; receiving third link state information from the second network device, wherein the third link state information carries information for computing a route to the third network device; in response to receiving the third link state information, recording the route to the third network device in a routing table; receiving first link state information sent by the second network device, wherein the first link state information is link state information of the third network device; in response to receiving the first link state information, deleting the second link state information, wherein the forwarding entry associated with the third network device is deleted from the forwarding table when the second link state information is deleted; and deleting, based on the first link state information, the third link state information, wherein the route to the third network device is deleted from the routing table when the first link state information is deleted. ### Claim 12 (depends on 11) The non-transitory computer readable storage medium according to claim 11, wherein the first link state information carries an indication identifier, and the indication identifier indicates to a network device that receives the first link state information to delete the third link state information. ### Claim 13 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein deleting, based on the first link state information, the third link state information received from the second network device comprises: deleting the third link state information in response to determining that the first link state information carries the indication identifier. ### Claim 14 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein the first link state information is carried in a link-state advertisement (LSA) defined according to an open shortest path first (OSPF) protocol, and the indication identifier is carried in an options field in a packet header of the LSA. ### Claim 15 A system, comprising: a first network device; and a second network device; and wherein the first network device is configured to: receive second link state information sent by a second network device, wherein the second link state information carries a segment identifier of a third network device; in response to receiving the second link state information, record a forwarding entry associated with the third network device in a forwarding table; receive third link state information sent by the second network device, wherein the third link state information carries information for computing a route to the third network device; in response to receiving the third link state information, record the route to the third network device in a routing table; receive first link state information sent by the second network device, wherein the first link state information is link state information of the third network device; in response to receiving the first link state information, delete the second link state information, wherein the forwarding entry associated with the third network device is deleted from the forwarding table when the second link state information is deleted; and delete, based on the first link state information, the third link state information, wherein the route to the third network device is deleted from the routing table when the first link state information is deleted. ### Claim 16 (depends on 15) The system according to claim 15, wherein the first link state information carries an indication identifier, and the indication identifier indicates to a network device that receives the first link state information to delete the third link state information. ### Claim 17 (depends on 16) The system according to claim 16, wherein deleting, based on the first link state information, the third link state information received from the second network device comprises: deleting the third link state information in response to determining that the first link state information carries the indication identifier. ### Claim 18 (depends on 16) The system according to claim 16, wherein the first link state information is carried in a link-state advertisement (LSA) defined according to an open shortest path first (OSPF) protocol, and the indication identifier is carried in an options field in a packet header of the LSA. ### Claim 19 (depends on 15) The system according to claim 15, wherein the first network device is a cell site gateway (CSG) and the second network device is an aggregation site gateway (ASG).