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AssigneeDigital Equipment Corporation
InventorsStuart R. Soloway, Anthony G. Lauck, George Varghese
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A method of providing loop free and shortest path routing of data packets in a network having a plurality of switches, routing messages for communicating network topology information between the switches, a plurality of links connecting the switches and a plurality of channels connecting the switches to the links. The loop free routing of data packets is achieved through modifications to known link state packet (LSP) routing protocols and permits each switch to inform adjacent switches in the network of the information in the switch's database used to compute forwarding tables. A switch uses a received LSP to compute a forwarding table and informs neighboring switches on attached links of the routing change. The switch discards any subsequent data packets whose path would be affected by the changed routing information. The discarding of data packets continues until the switch receives notification from each adjacent switch affected by the changed routing information that all affected routing paths have been recalculated and the forwarding table of each affected switch has been updated. Thus, while adjacent switches temporarily contain inconsistent LSP databases and possibly inconsistent forwarding tables, the looping of data packets is prevented. Shortest path routing for data packets from a source endnode to a destination endnode is achieved by assuring that the first switch to forward the packet is on the shortest path to the packet's destination endnode. A source endnode transmits a data packet with an appropriate destination header and the determination of the actual routing path is performed transparently to endnodes. A data packet reaches its destination endnode by following the shortest path possible based on the network topology as represented in the database of the first switch that forwards it.
A method of providing loop free routing of data packets in a network having a plurality of switches, routing messages for communicating network topology information between said switches, each of said switches having a routing database for storing said network topology information and routing path information used in forwarding packets, a plurality of links connecting said switches and a plurality of channels connecting said switches to said links, comprising the steps of:
A method of providing loop free routing of data packets in a network having a plurality of switches, routing messages for communicating network topology information between said switches, each of said switches having a routing database with a forwarding table including for each destination node in the network a pick-up bit and a hold down bit for each channel attached to the switch for storing said network topology information and routing path information used in forwarding packets, a plurality of links connecting said switches and a plurality of channels connecting said switches to said links, comprising the steps of:
A method of providing shortest path routing of data packets in a network having a plurality of switches routing messages for communicating network topology information between said switches, each of said switches having a routing database with a forwarding table for storing said network topology information and routing path information used in forwarding packets, a plurality of links connecting said switches and a plurality of channels connecting said switches to said links, comprising the steps of:
Dependencies are inferred from the claim text.