Abstract: A system for rapidly switching at least one virtual local area network (VLAN) from a first loop-free topology to a second loop-free topology in response to a failure within the first loop-free topology. Each VLAN has one “logical” VLAN which represents the network entities organized into the VLAN and a set of “physical” VLANs each having its own VLAN designation. For each physical VLAN, a different loop-free topology is defined, although only one physical VLAN is “active” at any given time. Messages associated with the logical VLAN are tagged with the designation of the currently active physical VLAN, and forwarded along its loop-free topology. Upon detecting a failure in the loop-free topology, the logical VLAN is rapidly switched to the loop-free topology defined by a second, back-up physical VLAN. Following the switch messages associated with the logical VLAN are tagged with the designation of this back-up VLAN and are forwarded along its loop-free topology.

Abstract: A system automatically discovers and maintains geographic location information for entities and devices making up a computer network. The system preferably includes a computing unit and a geographic location generator, such as a Global Positioning System (GPS) receiver. The computing unit includes a location discovery entity and a message generator. The GPS receiver, which is mounted to and in communication with the computing unit, may be augmented with an inertial navigation unit to facilitate the generation of location information inside of buildings where GPS signals can be difficult to receive. The computing unit further includes a network communications facility so that it can communicate with one or more network devices, such as a network switch. The switch includes a location recording/reporting entity and a location database.

Abstract: A system for efficiently organizing data or information into an associative memory device, such as a ternary content addressable memory (TCAM), for subsequent searching divides the TCAM is divided into a plurality of individual stages that are interconnected in a cascading fashion. The data or information that is to be stored into the TCAM for subsequent searching is initially translated into a first Boolean representation, such as a binary decision diagram (BDD), that is partitioned into a plurality of segments. Each segment defines one or more outputs, and the outputs from one segment define the inputs to the next segment. After partitioning the BDD and identifying the resulting outputs, each BDD segment along with its corresponding outputs is mapped into a particular stage of the TCAM.

Abstract: A system within a computer network identifies specific traffic flows originating from a given network entity and requests and applies appropriate policy rules or service treatments to the traffic flows. A network entity includes a flow declaration component that communicates with one or more application programs executing on the entity. The flow declaration component includes a message generator and an associated memory for storing one or more traffic flow data structures. For a given traffic flow, the application program issues one or more calls to the flow declaration component providing it with information identifying the traffic flows. The flow declaration component then opens a flow management session with a local policy enforcer that obtains policy rules or service treatments for the identified flow from a policy server and applies those rules or treatments to the specific traffic flows from the network entity.

Abstract: The invention relates to a method and apparatus for efficiently organizing, storing and evaluating access control lists (ACLs) for use by an intermediate network device of a computer network. The intermediate network device includes an ACL converter which, in turn, includes a boolean transformation engine that is operatively coupled to a boolean manipulation engine. The boolean transformation engine is configured to access the ACLs in first format and to translate them into a first boolean representation, such as binary decision diagram (BDD) format. The boolean manipulation engine is configured to perform one or more operations on the ACLs specified for a given interface, including a merge operation, so as to generate a single, unified ACL for the given interface. In order to resolve possibly conflicting actions output by the multiple ACLs, the ACL converter may utilize one or more predefined conflict resolution tables during the merging process.

Abstract: Methods and apparatus for implementing storage virtualization on a network device of a storage area network are disclosed. A frame or packet is received at a port of the network device. It is then determined that the frame or packet pertains to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network. A virtual-physical mapping between the one or more physical storage locations and the virtual storage location is then obtained. A new or modified frame or packet is then sent to an initiator or a target specified by the virtual-physical mapping.

Abstract: Methods and apparatus for encapsulating a packet or frame for transmission in a storage area network are disclosed. A packet or frame compatible with a standard protocol employed in the storage area network is received or generated. The packet or frame is then encapsulated with a virtual storage area network identifier. The packet or frame may further be encapsulated with at least one of a TTL value, MPLS information, and a type of traffic to be carried by the packet or frame. For instance, the type of traffic to be carried by the packet or frame may include Ethernet, Fibre Channel, and Infiniband. Once encapsulated, the encapsulated packet or frame is sent over the storage area network. For instance, the encapsulated packet or frame may be generated as well as transmitted by a switch over an inter-switch link in the storage area network.

Abstract: A method that rapidly reconfigures a computer network having a plurality of devices executing the spanning tree algorithm. First, one or more devices are configured and arranged so that one port, providing connectivity to the root, is in the forwarding state and the remaining ports, providing connectivity to the root, are in the blocked state. Next, one or more of the blocked ports are designated as back-up ports. Upon detection of a failure at the active forwarding port, one of the back-up ports immediately transitions from blocked to forwarding, thereby becoming the new active port for the device. Following the transition to a new active port, dummy multicast messages are transmitted, each containing the source address of an entity directly coupled to the affected device or downstream thereof. By examining the dummy multicast messages, other devices in the network learn to use to the new forwarding port of the affected device.

Abstract: A method that rapidly reconfigures a computer network having a plurality of devices executing the spanning tree algorithm. First, one or more devices are configured and arranged so that one port, providing connectivity to the root, is in the forwarding state and the remaining ports, providing connectivity to the root, are in the blocked state. Next, one or more of the blocked ports are designated as back-up ports. Upon detection of a failure at the active forwarding port, one of the back-up ports immediately transitions from blocked to forwarding, thereby becoming the new active port for the device. Following the transition to a new active port, dummy multicast messages are transmitted, each containing the source address of an entity directly coupled to the affected device or downstream thereof. By examining the dummy multicast messages, other devices in the network learn to use to the new forwarding port of the affected device.

Abstract: A system within a computer network identifies specific traffic flows originating from a given network entity and requests and applies appropriate policy rules or service treatments to the traffic flows. A network entity includes a flow declaration component that communicates with one or more application programs executing on the entity. The flow declaration component includes a message generator and an associated memory for storing one or more traffic flow data structures. For a given traffic flow, the application program issues one or more calls to the flow declaration component providing it with information identifying the traffic flows. The flow declaration component then opens a flow management session with a local policy enforcer that obtains policy rules or service treatments for the identified flow from a policy server and applies those rules or treatments to the specific traffic flows from the network entity.

Abstract: A method that rapidly reconfigures a computer network having a plurality of devices executing the spanning tree algorithm. First, one or more devices are configured and arranged so that one port, providing connectivity to the root, is in the forwarding state and the remaining ports, providing connectivity to the root, are in the blocked state. Next, one or more of the blocked ports are designated as back-up ports. Upon detection of a failure at the active forwarding port, one of the back-up ports immediately transitions from blocked to forwarding, thereby becoming the new active port for the device. Following the transition to a new active port, dummy multicast messages are transmitted, each containing the source address of an entity directly coupled to the affected device or downstream thereof. By examining the dummy multicast messages, other devices in the network learn to use to the new forwarding port of the affected device.

Abstract: A method that rapidly reconfigures a computer network having a plurality of devices executing the spanning tree algorithm. First, one or more devices are configured and arranged so that one port, providing connectivity to the root, is in the forwarding state and the remaining ports, providing connectivity to the root, are in the blocked state. Next, one or more of the blocked ports are designated as back-up ports. Upon detection of a failure at the active forwarding port, one of the back-up ports immediately transitions from blocked to forwarding, thereby becoming the new active port for the device. Following the transition to a new active port, dummy multicast messages are transmitted, each containing the source address of an entity directly coupled to the affected device or downstream thereof. By examining the dummy multicast messages, other devices in the network learn to use to the new forwarding port of the affected device.

Abstract: A system within a computer network identifies specific traffic flows originating from a given network entity and requests and applies appropriate policy rules or service treatments to the traffic flows. A network entity includes a flow declaration component that communicates with one or more application programs executing on the entity. The flow declaration component includes a message generator and an associated memory for storing one or more traffic flow data structures. For a given traffic flow, the application program issues one or more calls to the flow declaration component providing it with information identifying the traffic flows. The flow declaration component then opens a flow management session with a local policy enforcer that obtains policy rules or service treatments for the identified flow from a policy server and applies those rules or treatments to the specific traffic flows from the network entity.

Abstract: The Spanning Tree Protocol converges to a new configuration after the loss of a link. A new frame, known as a root link query request BPDU is transmitted to the root bridge in the spanning tree when a bridge detects an indirect link failure through the reception of an inferior BPDU on a blocked port. Each bridge forwards this root link query until the root link query reaches the last reachable upstream bridge or a bridge which has a different Tx_Root_Id than the one identified in the RLQ-REQ-BPDU. If the last reachable bridge is the root bridge identified in the RLQ-REQ-BPDU, then a second new frame known as an RLQ-ACK-BPDU is sent, and the bridge port receiving this acknowledgment BPDU is changed from a blocked port to a designated port. If the RLQ-REQ-BPDU reaches a bridge with a different Tx_Root_Id than the one in RLQ-REQ-BPDU, a third new frame known as RLQ-NAK-BPDU is sent.

Abstract: The Spanning Tree Protocol converges to a new configuration after the loss of a link. A new frame, known as a root link query request BPDU is transmitted to the root bridge in the spanning tree when a bridge detects an indirect link failure through the reception of an inferior BPDU on a blocked port. Each bridge forwards this root link query until the root link query reaches the last reachable upstream bridge or a bridge which has a different Tx_Root_Id than the one identified in the RLQ-REQ-BPDU. If the last reachable bridge is the root bridge identified in the RLQ-REQ-BPDU, then a second new frame known as an RLQ-ACK-BPDU is sent, and the bridge port receiving this acknowledgment BPDU is changed from a blocked port to a designated port. If the RLQ-REQ-BPDU reaches a bridge with a different Tx_Root_Id than the one in RLQ-REQ-BPDU, a third new frame known as RLQ-NAK-BPDU is sent.

Abstract: A shared spanning tree protocol (SSTP) creates a plurality of spanning trees (i.e., loop-free paths) which are shared among one or more virtual local area network (VLAN) designations for data transmission within a computer network. Each shared spanning tree includes and is defined by a primary VLAN and may be associated with one or more secondary VLANs. In order to associate VLAN designation(s) with a single shared spanning tree, network devices exchange novel shared spanning tree protocol data units (SST-PDUs). Each SST-PDU corresponds to a given primary VLAN and preferably includes one or more fields which list the secondary VLAN designations associated with the given primary VLAN. The association of VLAN designations to shared spanning trees, moreover, preferably depends on which path traffic is to follow as well as the anticipated load characteristics of the various VLANs. The association of VLAN designations to shared spanning trees thus provides a degree of load balancing within the network.

Abstract: A computer network having multiple, dissimilar network devices includes a system for implementing high-level, network policies. The high-level policies, which are generally device-independent, are translated by one or more policy servers into a set of rules that can be put into effect by specific network devices. Preferably, a network administrator selects an overall traffic template for a given domain and may assign various applications and/or users to the corresponding traffic types of the template. Location-specific policies may also be established by the network administrator. The policy server translates the high-level policies inherent in the selected traffic template and location-specific policies into a set of rules, which may include one or more access control lists, and may combine several related rules into a single transaction.

Abstract: A method that rapidly reconfigures a computer network having a plurality of devices executing the spanning tree algorithm. First, one or more devices are configured and arranged so that one port, providing connectivity to the root, is in the forwarding state and the remaining ports, providing connectivity to the root, are in the blocked state. Next, one or more of the blocked ports are designated as back-up ports. Upon detection of a failure at the active forwarding port, one of the back-up ports immediately transitions from blocked to forwarding, thereby becoming the new active port for the device. Following the transition to a new active port, dummy multicast messages are transmitted, each containing the source address of an entity directly coupled to the affected device or downstream thereof. By examining the dummy multicast messages, other devices in the network learn to use to the new forwarding port of the affected device.