# US 7,613,135 B2 · System and method for routing packet traffic > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,613,135 B2 - Document ID: US7613135B2 - Status: Granted - Kind: B2 - Application number: 11/549,329 - Filed: 2006-10-13 - Published: 2008-04-17 - Granted: 2009-11-03 - Earliest claimed: 2006-10-13 - Assignees: AT&T Intellectual Property I, L.P. - Inventors: Guangzhi Li; Robert Duncan Doverspike; Dongmei Wang - Web page: https://patentgrep.com/patent/US7613135B2 ## CPC - H04L 45/00: Routing or path finding of packets in data switching networks (routing or path finding in wireless networks H04W40/00) - H04L 12/18: for broadcast or conference {, e.g. multicast} - H04L 41/00: Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks - H04L 41/12: Discovery or management of network topologies - H04L 45/12: Shortest path evaluation - H04L 45/16: Multipoint routing - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system and method for routing packet traffic is disclosed. A system that incorporates teachings of the present disclosure may include, for example, a router having a routing element that routes packet traffic according to Internal Gateway Protocol (IGP) weights that prevent multicast packet traffic and unicast packet traffic from occupying a common unidirectional link. Other embodiments are disclosed. ## Claims ### Claim 1 A computer-readable storage medium in a Network Management System (NMS), comprising computer instructions for assigning Internal Gateway Protocol (IGP) weights to a topology of communication links coupled to routing nodes in a Packet-Switched Network (PSN) to prevent multicast packet traffic and unicast packet traffic from occupying a common unidirectional communication link, wherein different weights are iteratively assigned to the routing nodes in a PSN ring depending on their relation to a source node being either in a clockwise direction or a counter-clockwise direction until all nodes on the PSN are an integral part of a graph. ### Claim 2 (depends on 1) The storage medium of claim 1, comprising computer instructions for: assigning a first IGP weight to communication links carrying multicast packet traffic; and assigning a second IGP weight to communication links carrying unicast packet traffic. ### Claim 3 (depends on 2) The storage medium of claim 2, wherein one of the first and second IGP weight exceeds the other. ### Claim 4 (depends on 1) The storage medium of claim 1, wherein IGP conforms to one among Open Shortest Path First (OSPF), Intermediate System-Intermediate System (IS-IS) protocol, and Distance Vector (DV) routing protocol standards. ### Claim 5 (depends on 1) The storage medium of claim 1, comprising computer instructions for: identifying from the topology of the PSN a ring of routing nodes and corresponding communication links; assigning a first IGP weight to communications links of the ring in a clockwise direction; assigning a second IGP weight to communications links of the ring in a counterclockwise direction, thereby forming the graph; identifying one or more routing nodes and one or more corresponding communication links from the topology of the PSN, excluding those already part of the graph, that form a chain between two routing nodes of the graph; assigning the first IGP weight to communication links of the chain in the clockwise direction; assigning the second IGP weight to communications links of the chain in the counterclockwise direction, thereby expanding the graph; and repeating the foregoing steps after the first instantiation of the graph until all routing nodes and corresponding communication links in the PSN become an integral part of the graph. ### Claim 6 (depends on 5) The storage medium of claim 5, wherein one of the routing nodes of the ring comprises a source routing node. ### Claim 7 (depends on 5) The storage medium of claim 5, comprising computer instructions for selecting the ring with a minimum ring size. ### Claim 8 (depends on 5) The storage medium of claim 5, comprising computer instructions for selecting each chain with a minimum chain size. ### Claim 9 (depends on 6) The storage medium of claim 6, wherein the source routing node comprises a unicast server, and wherein the storage medium comprises computer instructions for selecting one or more chains that increase diversification of unicast traffic supplied by the unicast server. ### Claim 10 (depends on 6) The storage medium of claim 6, comprising computer instructions for selecting each chain according to a breadth first search method. ### Claim 11 (depends on 1) The storage medium of claim 1, comprising computer instructions for presenting a Graphical User Interface (GUI) representing at least one among a resultant topology of communication links coupled to routing nodes of the PSN with unicast and multicast packet traffic routing indications, a multicast topology from the resultant topology, and a unicast topology from the resultant topology. ### Claim 12 A router, comprising a routing element that routes packet traffic according to Internal Gateway Protocol (IGP) weights that prevent multicast packet traffic and unicast packet traffic from occupying a common unidirectional link, wherein the routing element receives from a Network Management System (NMS) the IGP weights corresponding to a topology of communication links coupled to routers in a Packet-Switched Network (PSN) from which the router operates and the NMS assigns a first IGP weight to communication links carrying multicast packet traffic, and assigns a second IGP weight to communication links carrying unicast packet traffic; and wherein the NMS identifies from the topology of the PSN a ring of routers and corresponding communication links, assigns a first IGP weight to communications links of the ring in one direction, assigns a second IGP weight to communications links of the ring in an opposite direction, thereby forming a graph, identifies one or more routing nodes and one or more corresponding communication links from the topology of the PSN, excluding those already part of the graph, that form a chain between two routing nodes of the graph, assigns the first IGP weight to communication links of the chain in the one direction, assigns the second IGP weight to communications links of the chain in the opposite direction, thereby expanding the graph, and repeats the foregoing steps after the first instantiation of the graph until all routing nodes and corresponding communication links in the PSN become an integral part of the graph. ### Claim 13 (depends on 12) The router of claim 12, wherein one of the routers of the ring comprises a source routing node for transporting one among unicast and multicast packet traffic. ### Claim 14 (depends on 12) The router of claim 12, wherein the NMS selects the ring with a minimum ring size. ### Claim 15 (depends on 12) The router of claim 12, wherein the NMS selects each chain with a minimum chain size. ### Claim 16 (depends on 12) The router of claim 12, wherein the NMS selects one or more chains that increase diversification of unicast traffic supplied by a unicast server. ### Claim 17 A method, comprising preventing multicast and unicast packet traffic in a Packet-Switched Network (PSN) from occupying a common unidirectional communication link by manipulating routing weights, wherein the routing weights conform to an Internal Gateway Protocol (IGP), and wherein the method comprises: identifying from the topology in the PSN a ring of routing nodes and corresponding communication links; assigning a first and second IGP weights to communications links of the ring in clockwise and counterclockwise directions; identifying one or more routing nodes and one or more corresponding communication links from the topology of the PSN, excluding those already part of a graph, that form a chain between two routing nodes of the graph; assigning the first and second IGP weights to communication links of the chain in clockwise and counterclockwise directions; and repeating the foregoing steps after the first instantiation of the graph until all routing nodes and corresponding communication links in the PSN become an integral part of the graph.