# US 10,320,653 B2 · Route topology discovery in data networks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,320,653 B2 - Document ID: US10320653B2 - Status: Granted - Kind: B2 - Application number: 15/612,645 - Filed: 2017-06-02 - Published: 2017-09-21 - Granted: 2019-06-11 - Earliest claimed: 2011-09-23 - Assignees: Nectar Holdings, Inc. - Applicants: Nectar Holdings, Inc. - Inventors: Lance Arnold Visser - Web page: https://patentgrep.com/patent/US10320653B2 ## CPC - H04L 45/02: Topology update or discovery - H04L 41/12: Discovery or management of network topologies - H04L 45/028: Dynamic adaptation of the update intervals, e.g. event-triggered updates - H04L 45/123: {Evaluation of link metrics (techniques for monitoring network metrics H04L43/08)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system and method for performing topology discovery in a data network is provided. Network elements utilizing a distance-vector protocol, such as EIGRP, advertises routes and metric information. A resource control point or other element analyzes the advertised routes and metrics and determines the nexthop, thereby providing a topology map of the network. ## Claims ### Claim 1 A method of performing topology discovery, the method comprising: utilizing, by a first resource control point, a first routing protocol to communicate with at least one of a plurality of first network elements comprising a first network domain to obtain respective routing information for each of the plurality of first network elements, wherein the routing information comprises metric information for each of a plurality of routes; determining if a route in the plurality of routes is an unresolved route having an unresolved next-hop network element; using the metric information to resolve the unresolved next-hop network element by comparing the metric information of the unresolved route to metric information of another route in the plurality of routes and a link metric associated with a network element in the other route; utilizing, by the first resource control point, the routing information to determine first network elements that connect to a second network domain; establishing, by the first resource control point, a connection with a second resource control point in the second network domain; and utilizing, by the first resource control point, the connection to notify the second resource control point of the first network elements that connect to the second network domain. ### Claim 2 (depends on 1) The method of claim 1 further comprising: utilizing, by the first resource control point, the first routing protocol to determine a change in the first network domain; and communicating, by the first resource control point and to the second resource control point, information corresponding to the change in the first network domain. ### Claim 3 (depends on 2) The method of claim 2 wherein the change in the first network domain comprises at least one of failure of at least one of the first network elements, the addition of a connection with the second network domain, and the removal of a connection with the second network domain. ### Claim 4 (depends on 1) The method of claim 1 wherein the first resource control point utilizes the first routing protocol to imitate being another first network element with the at least one of the plurality of first network elements to obtain the respective routing information for each of the plurality of first network elements. ### Claim 5 (depends on 4) The method of claim 4 wherein the first routing protocol is at least one of Open Shortest Path First (OSPF) protocol, Border Gateway Protocol (BGP), Intermediate System-Intermediate System (ISIS) protocol, Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), and Enhanced IGRP (EIGRP). ### Claim 6 (depends on 5) The method of claim 5 wherein the first resource control point obtains the respective routing information only from the first network elements having unique OSPF area routing information. ### Claim 7 (depends on 5) The method of claim 5 wherein the first resource control point uses the BGP protocol to obtain routing information associated with the second network domain. ### Claim 8 (depends on 5) The method of claim 5 wherein the first resource control point establishes Internal BGP peering sessions with each BGP-capable network element in the plurality of first network elements. ### Claim 9 (depends on 5) The method of claim 5 further comprising the first resource control point utilizing at least one of Simplified Network Management Protocol (SNMP), a command line interface (CLI), and an extended markup language (XML) to obtain additional routing information from one or more of the first network elements. ### Claim 10 (depends on 9) The method of claim 9 wherein the additional routing information includes at least one of static routing information, Multi-Label Protocol Label Switching (MPLS) tunnel characteristics, link names, network element names, status information, capacity information, secondary internet protocol (IP) addresses, a routing distance policy, and a route redistribution policy. ### Claim 11 (depends on 1) The method of claim 1 wherein the first resource control point and the second resource control point use the connection to notify each other of first network elements and second network elements that comprise the respective edges of the first network domain and the second network domain. ### Claim 12 (depends on 11) The method of claim 11 wherein the connection utilizes a Common Open Policy Service (COPS) protocol. ### Claim 13 (depends on 1) The method of claim 1 further comprising resolving the unresolved next-hop network element as local if the unresolved route is traced back to a connected or external route of a first router in the unresolved route. ### Claim 14 (depends on 1) The method of claim 1 further comprising the first resource control point: saving the routes in a routing table at the first resource control point; receiving information regarding removal of a first route of the routes; determining if the first route matches a resolved route in the routing table and, if the first route matches a resolved route in the routing table, removing the first route from the routing table; and resolving next-hops of the routes after the removing the first route. ### Claim 15 (depends on 13) The method of claim 13 further comprising: determining a neighboring router of the first router; determining if a matching route recorded in the first router is resolved; and using the metric information to resolve the unresolved next-hop network element by determining if the metric information of the unresolved route equals a sum of a link metric of the matching route and a link metric of an interface associated with the neighboring router. ### Claim 16 A non-transitory computer-readable media comprising instructions configured to cause a computer to perform steps comprising: utilizing, by a first resource control point, a first routing protocol to communicate with at least one of a plurality of first network elements comprising a first network domain to obtain respective routing information for each of the plurality of first network elements, wherein the routing information comprises metric information for each of a plurality of routes; determining if a route in the plurality of routes is an unresolved route having an unresolved next-hop network element; using the metric information to resolve the unresolved next-hop network element by comparing the metric information of the unresolved route to metric information of another route in the plurality of routes and a link metric associated with a network element in the other route; utilizing, by the first resource control point, by routing information to determine first network elements that connect to a second network domain; establishing, by the first resource control point, a connection with a second resource control point in the second network domain; and utilizing, by the first resource control point, the connection to notify the second resource control point of the first elements that connect to the second network domain. ### Claim 17 (depends on 16) The non-transitory computer-readable media of claim 16 further comprising instructions configured to cause the computer to perform steps comprising: resolving the unresolved next-hop network element as local if the unresolved route is traced back to a connected or external route of a first router in the unresolved route; determining a neighboring router of the first router; determining if a matching route recorded in the first router is resolved; and using the metric information to resolve the unresolved next-hop network element by determining if the metric information of the unresolved route equals to sum of a link metric of the matching route and a link metric of an interface associated with the neighboring router.