# US 2008/0186978 A1 · Method and Independent Communications Subnet for Determining Label-Switched Routes a Communications Subnet of this Type > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186978 A1 - Document ID: US20080186978A1 - Status: Published application - Kind: A1 - Application number: 11/917,860 - Filed: 2006-05-18 - Published: 2008-08-07 - Earliest claimed: 2005-06-16 - Assignees: Deutsche Telekom AG - Inventors: Ruediger Geib - Web page: https://patentgrep.com/patent/US20080186978A1 ## CPC - H04L 45/00: Routing or path finding of packets in data switching networks (routing or path finding in wireless networks H04W40/00) - H04L 45/302: Route determination based on requested QoS - H04L 45/507: {Label distribution} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The invention relates to a method for determining label-switched routes between a source router and a target router (11, 14; 21, 24) of an independent communications subnet (10; 20), over which information packets having a predetermined IP target address are to be transmitted. The present invention furthermore relates to an independent communications subnet suitable for implementing the method as well as to routers used therein. The basic idea of the present invention is to couple the label-distributing multi-protocol, hitherto only used in IP backbone networks, with an internal subnet route protocol that is used in independent communications subnets so as to be able to design the routing of information packets over different route topologies in an independent communications subnet to be more efficient and faster. ## Claims ### Claim at position 1 1-7. (canceled) ### Claim 8 A method for determining label-switched routes between a source router and a target router of an independent communications subnet, over which information packets having a predetermined target address are to be transmitted, comprising: as a function of at least one parameter, calculating different route topologies within the communications subnet using an IP-based internal subnet routing protocol, a topology routing table for each route topology to which a router belongs being stored in this router; determining the route topologies and the associated routers, over which the information packets having the predetermined target address are to be transmitted from the source router to the target router; using the conventional label distribution protocol, assigning a label to each path that belongs to a determined route topology. ### Claim 9 (depends on 8) The method as recited in claim 8, wherein the label distribution protocol is used in a multi-protocol label switching (MPLS) architecture, the internal subnet routing protocol being a link-state protocol. ### Claim 10 (depends on 9) The method as recited in claim 9, further comprising transmitting MPLS information packets that contain a label field and an EXP field over the independent communications subnet. ### Claim 11 (depends on 8) The method as recited in claim 8, further comprising determining by the routers that belong to multiple route topologies different labels for outgoing paths. ### Claim 12 (depends on 10) The method as recited in claim 10, further comprising analyzing by the routers the label field and the EXP field of the received MPLS packets. ### Claim 13 A router for use in an independent communications subnet, including a device that executes an IP-based internal subnet routing protocol in order to determine different route topologies within an independent communications subnet as a function of at least one parameter, in particular of the quality of service (QoS) of the information to be transmitted; a device that executes the label distribution protocol in order to determine with every neighboring router belonging to the same route topology a label for the path lying between neighboring routers; and a memory device for storing at least one topology routing table and at least one label-based routing table. ### Claim 14 An independent communications subnet for implementing a method for determining label-switched routes between a source router and a target router of an independent communications subnet, over which information packets having a predetermined target address are to be transmitted, comprising: as a function of at least one parameter, different route topologies within the communications subnet are calculated using an IP-based internal subnet routing protocol, a topology routing table for each route topology to which at least one of the source router and target router belongs being stored in the respective associated router; the route topologies and the associated routers are determined, over which the information packets having the predetermined target address are to be transmitted from the source router to the target router; using a label distribution protocol, a label is assigned to each path that belongs to a determined route topology. ### Claim 15 (depends on 8) The method as recited in claim 8, wherein the at least one parameter is a quality of service (QoS) of the information to be transmitted. ### Claim 16 (depends on 9) The method as recited in claim 9, wherein the internal subnet routing protocol is at least one of an intermediate system to intermediate system routing protocol and an open shortest path first routing protocol.