Abstract: Techniques are described that increase the reliability and quality of data transmissions of computer networks. The techniques provide for the generation of at least two duplicate data flows for carrying data in a computer network. The duplicate data flows are transmitted to a receiving device along paths within one or more intermediate networks. In addition, network devices, such as routers or switches within the network, for example, may cooperate to select paths for the data flows that have reduced or minimal common network elements. The network devices may share “fate-sharing” information that relates groups of network elements according to common characteristics, attributes or shared resources, e.g., a shared power supply, close proximity, common physical interface, for the purposes of facilitating selection of independent paths.

Abstract: An ATM multiplexing apparatus for selectively performing cell discard processing in the case of congestion, on the basis of a use state of the same connection formed by cells from the side of an ATM switching unit and subscribers without installing UPC units. The ATM multiplexing apparatus, which is connected to the ATM switching unit and plural subscribers though ATM communication lines, performs multiplex processing to ATM cells sent from the plural subscribers. The ATM multiplexing apparatus has a detection means for detecting a level of a congestion state corresponding to the ATM cells received from the subscribers and discard means for selectively discarding the ATM cells received from the subscribers on the basis of a communication state determined by the ATM cells received from the ATM switching unit, ATM cells received from the subscribers and a level value of a warning signal indicating the detected congestion state.

Abstract: A network device is configured to receive a registration message from a private user device including a private internet protocol (IP) address associated with the private user device. A public IP address and discrete port number are assigned to the private user device and private IP address and stored in an incoming call table. The registration message is translated to include the public IP address and discrete port number. The registration message is forwarded to a proxy server for registration. An incoming call invitation message is received from a public user device, where the call invitation message is directed to the public IP address and discrete port number associated with the private user device. The call invitation message is translated to include the private IP address associated with the private user device based on the received public IP address and discrete port number and the incoming call table. The call invitation message is forwarded to the private user device.

Abstract: The invention provides a device for reducing ingress noise in a digital signal, comprising a noise predictor for predicting an amount of ingress noise in the digital signal based on past samples of the ingress noise, and a subtractor for subtracting the predicted amount of ingress noise from the digital signal. Channel distortion is compensated for by a noise-independent equalizer, such as a ZF equalizer, placed upstream of the noise predictor. The device may be incorporated, for example, in a cable modem termination system (CMTS) of an hybrid fiber/coax (HFC) network.

Abstract: In general, the invention is directed to techniques for improving memory utilization in a priority queuing system of a network device. More specifically, a priority queue memory management system is described in which memory pages are assigned to the various priority queues in order to implement an efficient first in, first out (FIFO) functionality. The dynamic memory techniques described herein allow the multiple priority queues to share a common memory space. As a result, each priority queue does not require a pre-allocated amount of memory that matches the aggregate size of the packets that must be buffered by the queue.

Abstract: A device may receive a fragment of a fragmented data unit, determine a flow identifier that identifies a data flow with which the fragment is associated, and create a flow entry, based on the flow identifier, to store information associated with the data flow. The device may also determine a fragment key associated with the fragment, store a pointer to the flow entry based on the fragment key, correlate the fragment and another fragment, associated with the data flow, based on the fragment key and the pointer to the flow entry, and accumulate statistics associated with the fragment and the other fragment after correlating the fragment and the other fragment.

Abstract: A method for secure communications between a client and one of a plurality of servers performed on an intermediate device coupled to the client and the plurality of servers.

Abstract: A router receives a control plane message for constructing a first LSP to a destination within a network that conforms to a first type of LSP. The control plane message includes a label for the first LSP and an identifier that identifies a first type of data traffic. The router receives a second control plane message for constructing a second LSP that conforms to the first type of LSP. The second control plane message includes a label for the second LSP and an identifier that identifies a second type of data traffic. The router installs forwarding state in accordance with policies that associate the first and second types of data traffic with different LSPs of a second type that each traverse different paths through the network, and forwards packets via the interface in accordance with the installed forwarding state.

Abstract: An improved firewall for providing network security is described. The improved firewall provides for dynamic rule generation, as well using conventional fixed rules. This improvement is provided without significant increase in the processing time required for most packets. Additionally, the improved firewall provides for translation of IP addresses between the firewall and the internal network.

Abstract: Techniques are described for reliable restoration of archived configuration. For example, a device, such as a router, comprises a first memory to store operational configuration data and a second memory to store candidate configuration data. The candidate configuration data represents a working copy of the operational configuration data. The device further includes a control unit to lock the candidate configuration data, load archived configuration data to replace the locked candidate configuration data and commit the candidate configuration data to restore the archived configuration data as the operational configuration data of the device. In locking the candidate configuration, the device ensures reliable restoration of the candidate configuration by helping prevent the device from becoming both unreachable and inoperable.

Abstract: The present invention is directed to obtain a statistic multiplexing effect in an image transmission system using terminals stipulated by H.310 of an ITU-T recommendation. In a network including a first local area ATM network, a second local area ATM network and a public ATM network connected to the first and second ATM local area networks, multiplex gateway devices are interposed between the local area ATM networks and the public ATM network, respectively. The multiplex gateway apparatus includes ATM transmission line units 21 to 23 for calculating statistic information represented by a mean rate and a peak cell rate of ATM cells in the transmission ATM signal. A statistic multiplexing control unit 24 conducts rate addition after statistic multiplexing according to the statistic information and determines the rate addition result.

Abstract: A network layer device controls provision of data link layer functionality by a data link layer device to provide a requested multimedia service to a subscriber. For example, the network layer device may control the performance of multicast elaboration by the data link layer device, or the queuing and forwarding of packets by the data link layer device to facilitate transmission of packets according to a Quality of Service class. The network layer device may send control messages to the data link layer device to dynamically configure a control object stored by the data link layer device, such as multicast filter information or a Quality of Service profile. The network layer device may be a service edge router, and the data link layer device may be a customer premises equipment device, e.g., a modem or wireless access point, or a switch, e.g., a digital subscriber line access multiplier.

Abstract: The invention provides an arbitration method and an arbiter circuit by which equal arbitration of output cells can be achieved with a comparatively simple configuration even where a very great number of queues are involved. The arbiter circuit includes a plurality of queues for storing output cells, and a plurality of round robins for successively providing the right of outputting output cells to the queues. The round robins are arranged in a multi-stage tree link configuration, and the queues are distributed under those of the round robins which are in the lowest order stage. Each of the round robins in the lowest order stage has a rate information holding function of holding rate information representative of a rate of cells inputted thereto.

Abstract: A router includes multiple routing engines. If the active routing engine fails, a backup one of the routing engines detects the failure and assumes the role of active routing engine. A redundancy controller circuit, connected to the multiple routing engines, facilitates the selection and switching of the routing engines. Portions of the packet forwarding engine, in addition to the routing engine, may be redundantly implemented. The active routing engine controls the selection of the redundant portion of the packet forwarding engine.

Abstract: A system provides congestion control and includes multiple queues that temporarily store data and a drop engine. The system associates a value with each of the queues, where each of the values relates to an amount of memory associated with the queue. The drop engine compares the value associated with a particular one of the queues to one or more programmable thresholds and selectively performs explicit congestion notification or packet dropping on data in the particular queue based on a result of the comparison.

Abstract: A router receives a packet at an ingress interface. The router classifies the received packet based on at least a first field value contained in the header of the packet. According to the classification of the received packet, the router associates one of the plurality of forwarding tables to the packet. The router then performs a lookup operation in the associated forwarding table according to at least a second field value contained in the header of the packet. Based on the lookup operation, the router determines an egress interface and transmits the received packet from the determined egress interface.

Abstract: A cross-bar switch includes a set of input ports to accept data packets and a set of sink ports in communication with the input ports to forward the data packets. Each sink port includes a communications link interface with a Retry input. When a signal is asserted on the Retry input, the sink port aborts transmission of a data packet and waits a predetermined period of time to retransmit the data packet.

Abstract: A network access device is described that uses a modified lower layer two (L2) software interface that is enhanced to operate as a proxy for a dynamic upper L2 software interface when the upper L2 software interface has been torn down, i.e., terminated unbeknownst to a subscriber device. The lower L2 software interface may, for example, be extended to incorporate certain features of the upper L2 software interface to detect such a condition. In the absence of the upper L2 software interface, the lower L2 interface may output a simulated termination request on behalf of the upper L2 interface and in accordance with the upper L2 protocol.

Abstract: A first-in-first-out (FIFO) queue optimized to reduce latency in dequeuing data items from the FIFO. In one implementation, a FIFO queue additionally includes buffers connected to the output of the FIFO queue and bypass logic. The buffers act as the final stages of the FIFO queue. The bypass logic causes input data items to bypass the FIFO and to go straight to the buffers when the buffers are able to receive data items and the FIFO queue is empty. In a second implementation, arbitration logic is coupled to the queue. The arbitration logic controls a multiplexer to output a predetermined number of data items from a number of final stages of the queue. In this second implementation, the arbitration logic gives higher priority to data items in later stages of the queue.

Abstract: A method includes receiving one or more of user information, role information, or authorization information associated with a user accessing a network, selecting a traffic flow to monitor that is associated with the one or more of user information, role information, or authorization information, monitoring the traffic flow, determining whether an anomaly exists with respect to the traffic flow based on a traffic behavior pattern associated with the one or more of user information, role information, or authorization information, and performing a security response when it is determined that the anomaly exists.