Abstract: A network device, such as a router, utilizes a virtual interface to hide the presence of redundant backup physical interfaces from a router control unit. If traffic needs to be redirected from a primary physical interface, the router remaps the virtual interface to the backup physical interface without needing to update routes and select one or more alternative routes due to the need to redirect traffic. Instead, the router control unit redirects network traffic associated with the primary physical interface to the associated backup physical interface. In this manner, delays associated with route updating can be avoided, and a relatively seamless switchover can be achieved from the primary to the backup physical interface.

Abstract: This disclosure describes techniques of determining whether a symbol stream includes a pattern defined by a regular expression. As described herein, the regular expression may be represented using a non-deterministic finite automaton (NFA). A plurality of states in the NFA may be evaluated in parallel. These states may be associated with a plurality of symbol positions in a symbol stream. Evaluating a plurality of states and symbols in parallel may allow for faster determinations of whether the symbol stream includes the pattern defined by the regular expression.

Abstract: A method and apparatus for provisioning virtual upstream channels within one physical upstream channel. Each virtual upstream channel is assigned to a group of cable modems that share certain operational parameters. New virtual upstream channels can be provisioned as needed and existing virtual upstream channels can be deleted, as needed.

Abstract: This disclosure describes techniques for determining whether network traffic contains one or more computer security threats. In order to determine whether a symbol stream conforms to the symbol pattern, a security device stores a full deterministic finite automaton (fDFA) that accepts streams of symbols that conform to the symbol pattern. The security device also creates a partial deterministic finite automaton (pDFA) that includes nodes that correspond to the nodes in the fDFA that have the highest visitation levels. The security device processes each symbol in the symbol stream using the pDFA until a symbol causes the pDFA to transition to a failure node or to an accepting node. If the symbol causes the pDFA to transition to the failure node, the security device processes the symbol and subsequent symbols in the symbol stream using the fDFA.

Abstract: A network device displays applied and non-applied configurations in different formats to facilitate distinguishing between active and inactive configurations. In this way, a user can readily distinguish, for example, between applied configurations for active interfaces from loaded configurations for inactive interfaces and non-applied configurations for active interfaces. Configuration information may be encoded using an extensible markup language to identify the type of configuration. The network device uses this type identification to determine whether a particular part of the configuration should be displayed in as normal text or as altered text. The part of the configuration that is displayed in the altered form may represent the non-applied configurations.

Abstract: A network includes a media server and a service activation device. The media server may receive a request for content from a subscriber device and transmit a message. The message may identify the subscriber device and include information relating to the content. The service activation device may receive the message from the media server, identify, in response to receiving the message, bandwidth and quality of service requirements for the content, determine whether resources needed to provide the identified bandwidth and quality of service requirements exist, reserve the resources when the resources needed to provide the identified bandwidth and quality of service requirements exist, and transmit a second message to the media server in response to reserving the resources. The second message may cause the media server to provide the content to the subscriber device.

Abstract: In an ATM exchange, a cell transmission control section transmits an ATM cell to a transmission path of an ATM network. A traffic monitor monitors traffic of the cell transmissions. A statistical process section performs a temporal statistical process on the result of the traffic monitoring using a clock and a memory. A CAC produces an instruction for traffic control over a transmission terminal based on the result of the statistical process. A UPC controls traffic of a transmission path from the transmission terminal in accordance with the instruction.

Abstract: A data compression system and method for that is capable of detecting and eliminating repeated phrases of variable length within a window of virtually unlimited size.

Abstract: A network router makes use of embedded memory and external memory to handle packet buffering requirements for inbound and outbound packets. In particular, the router incorporates an embedded memory device to buffer first packets. This embedded memory device is used instead of a conventional external memory device, making pins that would otherwise be used to communicate with such an external memory device available for other purposes, such as for communicating with an external memory device that buffers second data packets. As a result, using additional pins allows the router to communicate with the external memory device with increased bandwidth, thereby improving the bandwidth of the router.

Abstract: A network analyzer includes a hardware-based accounting engine that generates accurate statistics for traffic within a computer network. As the network analyzer receives packets, the accounting engine associates the network packets with respective routing prefixes, and updates flow statistics for the routing prefixes. In this manner, the accounting engine maintains accurate flow statistics for all packets received by network analyzer. The network analyzer includes a control unit that generates prefix data to control the granularity of the traffic analysis. The control unit analyzes the flow statistics maintained by the accounting engine, and adaptively updates the set of prefixes to control the granularity of the statistics. The control unit may generate the prefix data as a forwarding tree having resolution nodes. Each node may associate a network prefix with forwarding next hop data, as well as respective analysis control data to enable or disable flow analysis for the prefix.

Abstract: A routing protocol, such as the Border Gateway Protocol (BGP), is extended in a manner that allows the protocol to opaquely carry routing attributes associated with an origin of a routing advertisement, e.g., a customer network of associated with a virtual private network (VPN). These attributes are carried within routing communications using a separate attribute set, and are automatically utilized when delivering the routing advertisement to other customer networks associated with the VPN. As a result, the customer networks are isolated from the routing attributes used within an intermediate network coupling the customer networks.

Abstract: An arbiter performs arbitration over a plurality of queues and provides data to a plurality of mutually exclusive destinations using combination logic that logically combines a plurality of mutually exclusive vectors into a combination vector. Each of the mutually exclusive vectors corresponds to one of the plurality of mutually exclusive destinations. A number of vector arbiters perform arbitration on each mutually exclusive vector to select a position within the mutually exclusive vector. A combination arbiter performs arbitration on the combination vector to determine a position within the combination vector, which corresponds to the next queue to be serviced. A comparison element compares the position within a mutually exclusive vector and the position within the combination vector to determine the destination of the data within the next queue to be serviced.

Abstract: Techniques for distributing airflow for cooling an electronic device are described. Vanes positioned immediately after a set of cooling fans direct airflow over a plurality of components within the device. For example, the vanes may be designed to segment the net fan blade travel area into equal sections—one section per component—to accomplish balanced airflow distribution. Components requiring cooling include cards, e.g., printed circuit boards and the like. A plurality of cards may form slots between the cards and the vanes may divide the airflow equally among the slots to provide consistent cooling for each of the cards. Embodiments of the invention may be directed to distributing cooling airflows within a computing device, e.g., a network router or a server.

Abstract: A device for insertion and extraction of printed circuit boards or other components from a device or system such as a network router includes a positionable handle. The handle adjusts in a manner similar to a handle on a c-clamp, and may be repositioned relative to the centerline of a driveshaft of the device. Additionally, the handle may include internal detents that define selectable handle positions. Various handle positions may allow an operator to utilize limited available space and increase the mechanical advantage of the handle.

Abstract: Frames are relayed through a packet network by pre-pending a packet header to the frames. The packet may be formed in response to a timing mechanism indicating that the frames have been buffered for more than a threshold time interval. Alternatively, the packet may be formed in response to buffering a threshold number of frames. The packet is relayed through the packet network to an egress device. The egress device removes the header from the packet, and forwards the frames via one or more virtual circuits.

Abstract: An interface permitting users (i) to create a group (also referred to as a “source”) containing configuration statements and (ii) to direct the inheritance of that group's statements in the rest of the configuration information (also referred to as a “target”). The same group can be applied to different sections of the configuration information. Different sections of one group's configuration statements can be inherited in different places in the configuration information. Supporting such configuration groups allows users to create smaller, more logically constructed configuration files, thereby making it easier to configure and maintain data forwarding device software. For example, users can group together statements that are repeated in many places in the configuration, such as when configuring interfaces, and thereby limit updates to just the group.

Abstract: Techniques are described for centralized management of quality of service (QoS) characteristics of network data flows. A service management system maintains a database that associates access information, such as a username and password, with QoS information. A router of other network device associates a data flow with access information, and queries the service management system with the access information to obtain the QoS information. The router forwards data of the data flow in accordance with the QoS information obtained from the service management system. As the access information may be a username and password, an existing system, such as a Remote Authentication Dial-In User Service (RADIUS) system, may easily be adapted for use as the service management system. As a result, QoS information may easily be centrally managed for numerous routers or other network devices.

Abstract: A centralized memory allocation system utilizes write pointer drift correction. The memory stores data units. The memory controller receives a write request associated with a data unit and stores the data unit in the memory. The memory controller also transmits a reply that includes an address where the data unit is stored. The control logic receives the reply and determines whether the address in the reply differs from an address included in replies associated with other memory controllers by a given address range. When this occurs, the control logic performs a corrective action to bring an address associated with the memory controller back within a defined range.

Abstract: A service/device discovery protocol which allows a customer premise device (CPD) to automatically discover other CPDs sharing common service related characteristics, and techniques for self-configuration of the service are described. For example, when a new customer site or CPD is to be added to an existing shared service, the service discovery protocol allows a CPD at the new customer site to automatically discover the other customer sites and/or CPDs associated with the existing shared service. The self-configuration techniques allow the new CPD to automatically configure itself as a member of the shared service, and also allow the existing CPDs to update their service configuration information to include the new customer site and/or CPD.

Abstract: Techniques are described to replicate multicast packets in accordance with a hierarchical data structure. For example, upon receiving a multicast packet, a packet-forwarding engine may communicate the packet to packet-forwarding engines corresponding to starting nodes of the hierarchical data structure. The packet-forwarding engines corresponding to starting nodes of the hierarchical data structure may replicate the multicast packet for local interface cards, and forward the replicated packets to the network. Furthermore, the packet-forwarding engines may replicate the packet for packet-forwarding engines corresponding to downstream nodes. In this manner, the packet replication process is distributed throughout the router decreasing the complexity of necessary replication hardware. Furthermore, the packet replication process is highly scalable resulting in a latency of one fabric hop when the number of packet-forwarding engines doubles.