Abstract: A user authentication service for a communication network authenticates local users before granting them access to personalized sets of network resources. Authentication agents on intelligent edge devices present users of associated end systems with log-in challenges. Information supplied by the users is forwarded to an authentication server for verification. If successfully verified, the authentication server returns to the agents authorized connectivity information and time restrictions for the particular authenticated users. The agents use the information to establish rules for filtering and forwarding network traffic originating from or destined for particular authenticated users during authorized time periods. An enhanced authentication server may be engaged if additional security is desired. The authorized connectivity information preferably includes identifiers of one or more virtual local area networks active in the network.

Abstract: Multi-stage, all-pass optical filters used to make low-loss, multi-channel dispersion compensation modules are disclosed. The all-pass optical filters can be ring resonators in waveguides, Gires-Tournois Interferometers (GTIs) in free space form, and the like. The coupling constants and circulating path lengths may also be distinctively varied in each of the series of GTIs, tuning the net dispersion spectrum of the GTI set, such that the sum of the dispersions from the series of GTI's can provide a system with greater bandwidth than the same number of identical GTIs. The local dispersion slope can also be tuned in this manner. Multi-cavity GTIs can also be formed with similar performance enhancing properties.

Abstract: Methods for using a length dispersion of an etalon to approximate target resonant frequencies. Length dispersion usage in the present invention includes, for example, determining the impact of a length dispersion of an etalon on resonant frequencies of the etalon and may involve, for example, selection of one a more of a refractive index step, a number of layers, and a layer thickness of one or both dielectric stacks of the etalon in consideration of length dispersion. A featured method comprises defining target resonant frequencies and selecting an etalon having resonant frequencies which approximate the target resonant frequencies wherein the selection of the etalon is made based at least in part in consideration of a length dispersion of the etalon.

Abstract: Methods for configuring, maintaining connectivity in and utilizing an ATM network. Neighboring switches share topology information and enable links to neighboring switches for tag switching. Point-to-point tagged virtual connections are established between switches on the best and next-best paths learned from topology information. Point-to-multipoint tagged virtual connections are established on the spanning tree path. Multiple tag allocation requests are included in a single message to preserve bandwidth. Next-best paths are established to reduce latency in event of link failure. Forwarding operations may be performed in hardware to reduce latency during message forwarding.

Abstract: A bridge provides distributed multicast forwarding with sub-interface granularity. Forwarding decisions on multicast data packets transmitted on the bridge backplane are made by network interfaces by referencing local multicast databases. Each network interface forwards multicast data packets only on local ports which belong to the multicast group identified in the packet. A management interface transmits forwarding updates to the network interfaces. A particular network interface is made responsible for forwarding multicast packets to management interface for learning.

Abstract: A unified policy management system for an organization including a central policy server and remotely situated policy enforcers. The central policy server includes a central database storing configuration information for the remotely situated policy enforcers. Each policy enforcer includes a policy enforcer database storing a portion of the configuration information associated with the policy enforcer. Changes in the policy settings made at the central policy server are stored in a log for later processing and sending to the appropriate policy enforcers. Upon receipt of the change information, each receiving policy enforcer updates the portion of its policy enforcer database affected by the change.

Abstract: A unified policy management system for an organization including a central policy server and remotely situated policy enforcers. A central database and policy enforcer databases storing policy settings are configured as LDAP databases adhering to a hierarchical object oriented structure. Such structure allows the policy settings to be defined in an intuitive and extensible fashion. Changes in the policy settings made at the central policy server are automatically transferred to the policy enforcers for updating their respective databases. Each policy enforcer collects and transmits health and status information in a predefined log format and transmits it to the policy server for efficient monitoring by the policy server. For further efficiencies, the policy enforcement functionalities of the policy enforcers are effectively partitioned so as to be readily implemented in hardware.

Abstract: A physical network switch partitioned into a plurality of virtual routers (VRs) where each VR has allocated to it a set of resources and routing tables. The system resources are not tied to a particular network interface, allowing them to be flexibly partitioned among the various VRs. Each VR may also be partitioned into multiple virtual private networks (VPNs) for controlling access to certain portions of the VR. Access is controlled by filtering software that filters traffic directed to the VR based on criteria such as source and/or destination addresses.

Abstract: “Per memory” atomic access for a distributed memory multiprocessor architecture is provided by marking bit masks for shared memories to indicate the access privileges of processors to the memories. A processor has access privileges to a shared memory if the bit mask retained for the memory is marked at a bit position reserved for the processor and does not have access privileges if the bit mask is not so marked. A bit mask is permitted to have only one mark at a given time to guarantee that access to each shared memory is atomic.

Abstract: A user authentication service for a communication network authenticates local users before granting them access to personalized sets of network resources. Authentication agents on intelligent edge devices present users of associated end systems with log-in challenges. Information supplied by the users is forwarded to an authentication server for verification. If successfully verified, the authentication server returns to the agents authorized connectivity information and time restrictions for the particular authenticated users. The agents use the information to establish rules for filtering and forwarding network traffic originating from or destined for particular authenticated users during authorized time periods. An enhanced authentication server may be engaged if additional security is desired. The authorized connectivity information preferably includes identifiers of one or more virtual local area networks active in the network.

Abstract: In a switching device such as a network switch having multiple ports and shared buffer memory, method and apparatus for regulating the amount of buffer memory requested by a port. The method includes determining a limit number of buffers that a port may use from the number of available buffers in memory and the number of buffers in memory currently in use by the port. The limit number and number of buffers currently is use are then compared, and the comparison is used to determine whether a buffer request by the port will be generated. In an illustrative embodiment, determining the limit number includes adding the number of available buffers in memory with the number of buffers in memory currently in use by the port to obtain a sum, and multiplying the sum by a port allocation factor. The port allocation factor may be set independently for each port. Apparatus within the switching device practices the method in accordance with the invention.

Abstract: A switching device for forwarding network traffic to a desired destination on a network, such as a telephone or computer network. The switching device includes multiple ports and uses a lookup table to determine which port to forward network traffic over. The lookup table includes network addresses that are maintained in ascending or descending order. The switching device includes multiple binary search engines coupled in series including one or more precursor binary search engines and a final stage binary search engine. Together, the binary search engines perform an N iteration binary search. Additionally, a single search engine can perform multiple concurrent searches so that source and destination addresses can be obtained simultaneously and without wasted memory cycles.

Abstract: A switching fabric for a high-speed, high-performance digital traffic switch guarantees a high degree of resource availability and is resource efficient. Each input port associated with the switching fabric is assigned a time slot in a repetitive time cycle. Data cells received on input ports are staggered so that they are transmitted through the switching fabric in conformance with the assigned time slots. The time slot arrangement allows small data units associated with a particular cell, as they are forwarded through the switching fabric, to be converted into larger parallel data units which respect cell boundaries. The time slot arrangement further allows several of such larger data units to be written into an output queue in a single clock cycle. Thus, cell contention is avoided while making efficient use of queue space.

Abstract: A table lamp suitable for displaying a base-mounted finial has an adapter plate for supporting both a finial assembly and a pipe and wiring assembly using a single hole in the base. The adapter plate enables the pipe to be mounted outside the base perimeter while the hole is used for a finial assembly. The visual benefits of finials may thereby be extended to table lamp bases without defacing or modifying the visible surface of the base.

Abstract: A data transfer system efficiently allocates contiguous address spaces in a destination storage area to packets by maintaining a plurality of lists from which different amounts of contiguous address spaces are allocated. List selection is made based on known or presumed packet characteristics. By arranging different lists to supply contiguous address spaces in different amounts based on packet-specific characteristics, over-allocation of address space may be reduced considerably while contiguous address space is guaranteed on a continuous basis.

Abstract: A method and apparatus for switching/bridging frames between a heterogeneous media is disclosed. Bridges and/or switches normally bit-swap a MAC header of a frame when switching the frame between heterogeneous media. However, this practice introduces errors in address formats in certain situations. Such problems are resolved by investigating whether a frame to be switched includes local address components, and if so, these address components in the frame are manipulated to ensure that the address formats are proper for a media onto which the frame is being switched.

Abstract: An equalization device has a digital equalizer for joint tuning of a data-carrying signal distorted by analog transmission. The digital equalizer includes a closed-loop automatic gain control (AGC) circuit for applying a compensatory frequency-independent gain to the distorted signal followed by a frequency filter for applying a compensatory frequency-dependent gain to the signal. Joint tuning produces an output signal which more closely resembles the originally transmitted signal, facilitating recovery of implicit clock and more reliable data recovery. The digital equalizer may be advantageously stage-implemented as a preliminary digital equalizer which is preceded by an analog equalizer and followed by a final digital equalizer.

Abstract: Methods for configuring, maintaining connectivity in and utilizing an ATM network. Neighboring switches share topology information and enable links to neighboring switches for tag switching. Point-to-point tagged virtual connections are established between switches on the best and next-best paths learned from topology information. Point-to-multipoint tagged virtual connections are established on the spanning tree path. Multiple tag allocation requests are included in a single message to preserve bandwidth. Next-best paths are established to reduce latency in event of link failure. Forwarding operations may be performed in hardware to reduce latency during message forwarding.

Abstract: A CAM integrated circuit has a stage-implemented CAM cell which operationally separates CAM read operations into distinct stages, including look-up, prioritization and encoding, that execute independently. The staged implementation is achieved by placing registers between operational logic blocks in the CAM cell. The integrated circuit prioritizes inputs received simultaneously on dual input buses to avoid contention.

Abstract: A finial-adaptive pull chain has a bead chain disposed between an adaptor and a spring assembly. The adaptor retains the terminal bead of the bead chain, has external threads on the lower portion for receiving a finial and has a gripping surface on the upper portion to facilitate hand-manipulation during attachment. The upper portion has a diameter no greater than the lower portion so that the adaptor is substantially hidden from view when a finial is fully attached and does not unduly interfering with the decorative requirements of any end-user. The spring assembly has a spring for absorbing dynamic tensile forces applied during activation and deactivation to reduce the risk that the end-user will damage the electrical components of the associated device.