A method and apparatus for dynamically shifting between switching and routing packets efficiently to provide high throughput. The present invention provides a method for transmitting packets betwee an upstream node and a downstream node in a network that utilizes flow classification and labelling to redirect flows. The method includes the steps of establishing default virtual channels between the upstream node and the downstream node (1602), receiving packets at the downstream node, performing flow classification at the downstream node on the packet to determine whether the packet belongs to a specified flow that should be redirected in the upstream node (170), selecting a free label at the downstream node (1668) and informing the upstream node that future packets belonging to the specified flow should be sent with the selected free label attached (1676). Other embodiments of the invention include a basic switching unit (1, 3), a switch gateway unit (21), and a switching agent for use in a system for transmitting packets in a network.

Improved method and apparatus for dynamically shifting between routing and switching packets in a transmission network

Methods and apparatus for detecting faults and restoring connections in networks including, e.g., ATM networks are described. The restoration methods of the present invention can be applied on an application by application or user by user basis. In accordance with the present invention virtual connections affected by link or node failures are restored through re-routing as opposed to establishing a completely new connection between a source and a destination device. VPI/VCI values are assigned at the time of re-routing thereby avoiding the potential problem of VPI/VCI exhaustion which may be encountered when backup VPI/VCI values are assigned at the time a communication session is initiated. The connection restoration process of the present invention is initiated by a node on the source side of a connection detecting a failure and initiating a re-routing operation or transmitting a message to the source switch to initiate a re-routing operation. A node on the destination device side of a failed connection is used for initiating the release of network resources reserved at the switches which were used as part of the no longer used path of the re-routed call. The destination device side node (switch) detecting a fault transmits a re-route release message to downstream switches. Restoration methods applicable to pre-planned hop-by-hop, pre-planned source routing and dynamic source routing embodiments are described. In one embodiment, ATM assured mode data transport operation on signaling channels is used to detect node and/or link failures.

Methods and apparatus for restoring connections in an ATM network

A system and method are disclosed for using segment routing (SR) in native IP networks. The method involves receiving a packet. The packet is an IP packet and includes an IP header. The method also involves updating the packet. Updating the packet involves writing information, including a segment routing segment identifier, to the destination address of the packet.

Segment routing extension headers

An apparatus and method is disclosed for segment routing (SR). In one embodiment, the method includes a node creating a segment stack that identifies one segment calculated using a first algorithm and a second segment calculated using a second, different algorithm. The node then attaches this header to a packet and sends it to another node.

Segment Routing Techniques

A technique for updating a routing table in a routing device operating over a logical connection in a communication network utilizes a mechanism at a first protocol layer to determine a logical connection status and trigger a routing table update at a second protocol layer based upon the logical connection status. Specifically, the first protocol layer logic monitors the status of the logical channels, and, based on the status of the logical channels, determines the status of the logical connections. When the first protocol layer logic detects a logical channel failure that results in a logical connection failure, the first protocol layer logic triggers a routing table update by sending a signal to the second protocol layer logic indicating that the logical connection failed. Likewise, when the first protocol layer logic determines that communication over the failed logical connection is restored, the first protocol layer logic triggers a routing table update by sending a signal to the second protocol layer logic indicating that the logical connection is restored.

Expediting reconvergence in a routing device

An ATM switching system at each node of a network performs route changing or rerouting promptly when a failure occurs. In each of ATM switching systems at nodes N1 to N6: a route table 21 of a line interface 102 is set with conversion header information of a normal route, and an alternate routing table 25 is set with header information of one or more alternate routes. Subsequently, each line interface tests, when a packet arrives, whether or not a failure has occurred in an output line involved in the normal route, by referring to a bitmap 264 storing failure lines and a VP failures. The line interface executes header conversion by applying the normal header information stored in the routing table 21 in the case of no failure set for the normal route and by applying the header information stored in the alternate routing table 25 in case a failure has occurred on the normal route, and then outputs the packet to an ATM switch 101. Since the alternate route is promptly selected at the time of a failure of a net line and not in response to decoding a header of a received packet, the number of packets discarded due to the failure is reduced, and the rerouting operation is promptly executed even in the case of multiple failures.

Aim switching system and path changing method

PURPOSE: To quickly execute alternative operation at the occurrence of a fault. CONSTITUTION: At the time of setting up a connection, each ATM exchange sets up converting header information for a normal path in a line interface routing table 21 and sets up header information for a by-pass in an alternative routing table 25. Each line interface inspects the existence of a fault in an output line while referring to a bit map memory for storing a fault line and a fault VPI at the arrival of a cell, applies the header information stored in the table 21 when there is no fault or applies the header information stored in the table 25 when a fault exists in the output line to execute header conversion, and then outputs the cell to an ATM switch. Since an alternative route can be quickly selected when a fault exists in a network, the number of canceled cells due to the occurrence of a fault can be reduced, and even at the occurrence of a multiple fault, the alternative operation can be executed. COPYRIGHT: (C)1996,JPO

Noboru Endo

Papers

Aim switching system and path changing method

Atm exchange and method for switching path