Abstract: A technique is provided for facilitating information management in a storage area network. The storage area network may utilize a fibre channel fabric which includes a plurality of ports. The storage area network may also comprise a first volume which includes a first mirror copy and a second mirror copy. The storage area network may further comprise a mirror consistency data structure adapted to store mirror consistency information. A mirror consistency check procedure is performed to determine whether data of the first mirror copy is consistent with data of the second mirror copy. According to one implementation, the mirror consistency check procedure may be implemented using the consistency information stored at the mirror consistency data structure.

Abstract: A technique is provided for implementing online restriping of a volume in a storage area network. A first instance of the volume is instantiated at a first port of the fibre channel fabric for enabling I/O operations to be performed at the volume. While restriping operations are being performed at the volume, the first port is able to concurrently perform I/O operations at the volume.

Abstract: A network device is configured in a manner to prevent connectivity loops such as one way connectivity loops. A user configures a port of the network device to have an associated state. The state indicates that the port is for communication up the spanning tree towards a root network device, or down the spanning tree away from the root network device. The spanning tree protocol is then executed and determines a role for the port. The role determined by the spanning tree protocol is compared to the user selected state, and if there is an inconsistency, for example one that would indicate a one way connectivity loop, the port is blocked.

Abstract: Methods and apparatus are provided for improving fibre channel packet delivery. Techniques are provided for the in-order delivery of packets by blocking incoming packets associated with a port channel change at a fibre channel switch and sending flush messages onto links associated with a port channel change. Upon receiving acknowledgments for the flush messages, incoming packets are unblocked.

Abstract: Ports of a switch are assigned by a person, for example a network manager, to be for communication up the spanning tree toward the root switch (“up ports”), or down the spanning tree away from the root switch (“down ports”). This assignment is made by enabling “Uplinkguard” status for a desired up port, and by connecting the desired port to a switch which it is desired to place in the higher layer of the spanning tree. A port having Uplinkguard enabled is prevented, for example by software or firmware in its switch, from transitioning to a designated role. Uplinkguard-enabling a port, by preventing the port from transitioning to the designated role, has at least two consequences: preventing the port from being selected by the STP to transmit to lower switches in the spanning tree; and, preventing the port from transmitting when a one way connectivity fault develops on that port. A port with Uplinkguard enabled may transition to root port role.

Abstract: A method and apparatus allows for continued operation of one or more applications running at a network device with reduced delay despite crashes or failures at that device. The network device includes two or more supervisor cards for running the applications and a plurality of line cards. According to the invention, one supervisor card is designated the active supervisor card and one supervisor card is designated the standby supervisor card. As changes in state and other operating conditions take place on the active supervisor events are generating for passing at least some of this information to the standby supervisor where it is stored. Following a crash or failure of the active supervisor card, the standby becomes the newly active supervisor card. The standby supervisor performs a consistency check with the line cards and resets those that fail the check.

Abstract: A method of managing a computer network switch is disclosed. The method has the steps of: setting a port of the switch to root guard protected status (RG status); selecting by a spanning tree protocol (STP) the port as a designated port; and setting said port into blocked status, in response to said port being both in root guard protected status and selected by STP as a root port. By setting a port to root guard protected, the port is prevented from becoming a designated port, and so then forcing the root port to remain in a desired core network.

Abstract: The Spanning Tree Protocol (STP) chooses a root switch. Each of the other switches has a “root” port and one or more “designated ports(s)” chosen by STP. Packets are transmitted upstream toward the root switch through the root port, and packets designated for downstream switches from the root switch are received by the root port and transmitted through the designated ports. In the invention, an administrator of the core network identifies which switch ports in the core network are boundary ports to customer networks. The administrator designates the boundary ports as “root guard protected” ports (RG ports). The STP then executes as required by the ordinary STP protocol, and if a RG port is selected by the STP to be a root portm then the status of the port is set to “blocked,” and no packets are transmitted through the port.

Abstract: A multiple instance spanning tree protocol (MI-STP) creates a plurality of active topologies (i.e., loop-free paths) within a computer network. These active topologies may be established through the exchange and processing of multiple instance spanning tree bridge protocol data unit messages (MI-STP BPDUs) by the intermediate network devices within the network. The active topologies are preferably created independently of any virtual local area network (VLAN) designations defined within the network. Once the active topologies are defined, each VLAN designation is then mapped to a single active topology, although multiple VLAN designations are preferably mapped to the same active topology to provide load balancing.

Abstract: A scalable NAS file system and protocols for implementing CIFS thereon are disclosed. In certain embodiments, the protocols implement the CIFS protocol on a scalable file server architecture having one or more protocol termination nodes, one or more file server nodes, and one or more disk controller nodes. Among the features that may be specifically implemented are tree access, file access, user authentication, locking, state maintenance, and failover of protocol termination nodes and file server nodes.

Abstract: A multiple instance spanning tree protocol (MI-STP) creates a plurality of active topologies (i.e., loop-free paths) within a computer network. These active topologies may be established through the exchange and processing of multiple instance spanning tree bridge protocol data unit messages (MI-STP BPDUs) by the intermediate network devices within the network. The active topologies are preferably created independently of any virtual local area network (VLAN) designations defined within the network. Once the active topologies are defined, each VLAN designation is then mapped to a single active topology, although multiple VLAN designations are preferably mapped to the same active topology to provide load balancing.

Abstract: A method and apparatus for continuing the operation of a spanning tree protocol at a network device despite crashes or failures at that device. A supervisor card contained in the network device is designated an active supervisor, while all other supervisor cards are designated standby supervisors. The active supervisor runs the spanning tree protocol, and informs the standby supervisors of the states of ports, but not of the identity of the root or designated bridges. When a crash or failure occurs at the active supervisor, one of the standby supervisors is immediately designated to be the new active supervisor. The newly active supervisor reviews the port state, and queries the line cards to determine whether that port state information is still valid. The newly active supervisor adopts the valid port state information, leaving those ports in their current spanning tree port state.

Abstract: Ports of a switch are assigned by a person, for example a network manager, to be for communication up the spanning tree toward the root switch (“up ports”), or down the spanning tree away from the root switch (“down ports”). This assignment is made by enabling “Uplinkguard” status for a desired up port, and by connecting the desired port to a switch which it is desired to place in the higher layer of the spanning tree. A port having Uplinkguard enabled is prevented, for example by software or firmware in its switch, from transitioning to a designated role. Uplinkguard enabling a port, by preventing the port from transitioning to the designated role, has at least two consequences: preventing the port from being selected by the STP to transmit to lower switches in the spanning tree; and, preventing the port from transmitting when a one way connectivity fault develops on that port. A port with Uplinkguard enabled may transition to root port role.

Abstract: Efficient switched network multicasting techniques are provided. Incoming multicast packets are processed by a central forwarding engine (CFE) in a network switch to generate forwarding indices used to make forwarding decisions for the packets based upon whether the packets are special multicast control packets or data packets. Forwarding of the special multicast control packets is determined by the switch's network management processor (NMP), while data packets are forwarded based upon conventional bridge forwarding techniques.

Abstract: Efficient switched network multicasting techniques are provided. Incoming multicast packets are processed by a central forwarding engine (CFE) in a network switch to generate forwarding indices used to make forwarding decisions for the packets based upon whether the packets are special multicast control packets or data packets. Forwarding of the special multicast control packets is determined by the switch's network management processor (NMP), while data packets are forwarded based upon conventional bridge forwarding techniques.

Abstract: Efficient switched network multicasting techniques are provided. Incoming multicast packets are processed by a central forwarding engine (CFE) in a network switch to generate forwarding indices used to make forwarding decisions for the packets based upon whether the packets are special multicast control packets or data packets. Forwarding of the special multicast control packets is determined by the switch's network management processor (NMP), while data packets are forwarded based upon conventional bridge forwarding techniques.

Abstract: A method and apparatus facilitates and enhances the operation of the spanning tree protocol in bridged computer networks. An intermediate network device in accordance with the present invention includes an enhanced spanning tree engine that is configured to perform certain novel functions. First, the enhanced spanning tree engine is configured to identify and block ports at which messages are looped-back to the transmitting port, thereby avoiding the creation of network loops. In second aspect, the enhanced spanning tree engine rapidly transitions certain ports to a forwarding state to prevent associated applications from timing out and shutting down. Rather than moving the ports through blocking, listening and learning states before reaching the forwarding state, selected ports may be transitioned directly to the forwarding state.

Abstract: High availability for a fibre channel switch in a storage area network can be implemented using redundant supervisors. An active supervisor can identify high availability characteristics associated with a message and determine whether the message should be mirrored onto a redundant supervisor, logged, and/or made persistent. Messages can be logged in a pending transaction buffer and stored using persistent storage services. Mirroring can be performed using synchronization queues that allow messages to be passed asynchronously to a redundant supervisor while maintaining full synchronization between supervisors and causing little delay to operation of the active supervisor.

Abstract: Efficient switched network multicasting techniques are provided. Incoming multicast packets are processed by a central forwarding engine (CFE) in a network switch to generate forwarding indices used to make forwarding decisions for the packets based upon whether the packets are special multicast control packets or data packets. Forwarding of the special multicast control packets is determined by the switch's network management processor (NMP), while data packets are forwarded based upon conventional bridge forwarding techniques.

Abstract: Apparatus, methods and articles of manufacture for n-tier transaction execution and processing are shown. The first layer comprises a presentation layer in the form of a user interface for entering instrument orders, modifying orders, and monitoring orders, instruments and markets. The second layer comprises an intermediate component layer for information transfer, and the third layer comprises an information source layer for feeding information to and accepting information from the first two layers.