# US 8,542,578 B1 · System and method for providing a link-state path to a node in a network environment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,578 B1 - Document ID: US8542578B1 - Status: Granted - Kind: B1 - Application number: 12/850,307 - Filed: 2010-08-04 - Granted: 2013-09-24 - Earliest claimed: 2010-08-04 - Assignees: Cisco Technology, Inc. - Applicants: Clarence Filsfils; Ian Michael Charles Shand - Inventors: Clarence Filsfils; Ian Michael Charles Shand - Web page: https://patentgrep.com/patent/US8542578B1 ## CPC - H04L 45/68: {Pseudowire emulation, e.g. IETF WG PWE3} - G06F 11/00: Error detection; Error correction; Monitoring (error detection, correction or monitoring in information storage based on relative movement between record carrier and transducer G11B20/18; monitoring, i.e. supervising the progress of recording or reproducing G11B27/36; in static stores G11C29/00) - H04L 41/0659: by isolating or reconfiguring faulty entities - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An example method is provided and includes advertising information to network elements in a network environment. The information advertises a reachability characteristic of a first Internet protocol (IP) address associated with a first network element, and a second IP address associated with a second network element to which packets are to be sent instead of the first network element. The method also includes receiving the packets at the first network element, the packets being delivered from the second network element based on the information. In specific implementations, a preferred adjacency characteristic is identified in the information by a sub-TLV for routing the packets from the second network element to the first network element. If a failure occurs and a loop free alternate (LFA) protection mechanism is provisioned, the packets are sent via a label distribution protocol (LDP) label switched path (LSP) toward a designated interface of a network element. ## Claims ### Claim 1 A method, comprising: advertising information to network elements in a network environment, wherein the information advertises a reachability characteristic of a first Internet protocol (IP) address associated with a first network element, and a second IP address associated with a second network element to which packets are to be sent instead of the first network element; and receiving the packets at the first network element, wherein the packets are delivered from the second network element based on the information, wherein the information includes a preferred adjacency characteristic provided by a sub Type Length Value (sub-TLV) for routing the packets from the second network element to a preferred adjacent neighbor before reaching the first network element. ### Claim 2 (depends on 1) The method of claim 1, wherein the first network element is associated with a digital subscriber line access multiplexer (DSLAM). ### Claim 3 (depends on 1) The method of claim 1, wherein the first IP address is associated with a router having multiple loopback IP addresses that can be used for internal re-routing of incoming packets for the router. ### Claim 4 (depends on 1) The method of claim 1, wherein the first IP address is associated with a router that includes multiple line cards coupled to multiple interfaces, and wherein the information includes a sub-TLV that designates at least one of the interfaces over which packets are to be received. ### Claim 5 (depends on 1) The method of claim 1, wherein the information includes a sub-TLV that includes a weight attribute associated with a backup pathway for routing packets. ### Claim 6 (depends on 1) The method of claim 1, wherein if a failure occurs and a loop free alternate (LFA) protection mechanism is provisioned, the packets are sent via a label distribution protocol (LDP) label switched path (LSP) toward a designated interface of a network element. ### Claim 7 (depends on 1) The method of claim 1, wherein the information includes a sub Type Length Value (sub-TLV) to be provided in a link state packet TLV, and wherein the sub-TLV identifies the second IP address associated with the second network element, and wherein the sub-TLV is encapsulated in a TLV field of one or more link state protocol packets. ### Claim 8 Non-transitory media that includes code for execution and when executed by a processor operable to perform operations comprising: advertising information to network elements in a network environment, wherein the information advertises a reachability characteristic of a first Internet protocol (IP) address associated with a first network element, and a second IP address associated with a second network element to which packets are to be sent instead of the first network element; and receiving the packets at the first network element, wherein the packets are delivered from the second network element based on the information, wherein the information includes a preferred adjacency characteristic provided by a sub Type Length Value (sub-TLV) for routing the packets from the second network element to a preferred adjacent neighbor before reaching the first network element. ### Claim 9 (depends on 8) The media of claim 8, wherein the first network element is associated with a digital subscriber line access multiplexer (DSLAM). ### Claim 10 (depends on 8) The media of claim 8, wherein the first IP address is associated with a router having multiple loopback IP addresses that can be used for internal re-routing of incoming packets for the router. ### Claim 11 (depends on 8) The media of claim 8, wherein the first IP address is associated with a router that includes multiple line cards coupled to multiple interfaces, and wherein the information includes a sub-TLV that designates at least one of the interfaces over which packets are to be received. ### Claim 12 (depends on 8) The media of claim 8, wherein the information includes a sub-TLV that includes a weight attribute associated with a backup pathway for routing packets. ### Claim 13 (depends on 8) The media of claim 8, wherein if a failure occurs and a loop free alternate (LFA) protection mechanism is provisioned, the packets are sent via a label distribution protocol (LDP) label switched path (LSP) toward a designated interface of a network element. ### Claim 14 (depends on 8) The media of claim 8, wherein the information includes a sub Type Length Value (sub-TLV) to be provided in a link state packet TLV, and wherein the sub-TLV identifies the second IP address associated with the second network element, and wherein the sub-TLV is encapsulated in a TLV field of one or more link state protocol packets. ### Claim 15 An apparatus, comprising: a memory element configured to store electronic code, a processor operable to execute instructions associated with the electronic code, and an engineering-preferred path module configured to interface with the processor and the memory element such that the apparatus is configured for: advertising information to network elements in a network environment, wherein the information advertises a reachability characteristic of a first Internet protocol (IP) address associated with a first network element, and a second IP address associated with a second network element to which packets are to be sent instead of the first network element; and receiving the packets at the first network element, wherein the packets are delivered from the second network element based on the information, wherein the information includes a preferred adjacency characteristic provided by a sub Type Length Value (sub-TLV) for routing the packets from the second network element to a preferred adjacent neighbor before reaching the first network element. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the first network element is associated with a digital subscriber line access multiplexer (DSLAM). ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the first IP address is associated with a router having multiple loopback IP addresses that can be used for internal re-routing of incoming packets for the router. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the first IP address is associated with a router that includes multiple line cards coupled to multiple interfaces, and wherein the information includes a sub-TLV that designates at least one of the interfaces over which packets are to be received. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the information includes a sub-TLV that includes a weight attribute associated with a backup pathway for routing packets. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein the information includes a sub Type Length Value (sub-TLV) to be provided in a link state packet TLV, and wherein the sub-TLV identifies the second IP address associated with the second network element, and wherein the sub-TLV is encapsulated in a TLV field of one or more link state protocol packets.