The IEEE 802.11 Wireless LAN standards allow multiple non-overlapping frequency channels to be used simultaneously to increase the aggregate bandwidth available to end-users. Such bandwidth aggregation capability is routinely used in infrastructure mode operation, where the traffic to and from wireless nodes is distributed among multiple interfaces of an access point or among multiple access points to balance the traffic load. However, bandwidth aggregation is rarely used in the context of multi-hop 802.11-based LANs that operate in the ad hoc mode. Most past research efforts that attempt to exploit multiple radio channels require modifications to the MAC protocol and therefore do not work with commodity 802.11 interface hardware. In this paper, we propose and evaluate one of the first multi-channel multi-hop wireless ad-hoc network architectures that can be built using standard 802.11 hardware by equipping each node with multiple network interface cards (NICs) operating on different channels. We focus our attention on wireless mesh networks that serve as the backbone for relaying end-user traffic from wireless access points to the wired network. The idea of exploiting multiple channels is particularly appealing in wireless mesh networks because of their high capacity requirements to support backbone traffic. To reap the full performance potential of this architecture, we develop a set of centralized channel assignment, bandwidth allocation, and routing algorithms for multi-channel wireless mesh networks. A detailed performance evaluation shows that with intelligent channel and bandwidth assignment, equipping every wireless mesh network node with just 2 NICs operating on different channels can increase the total network goodput by a factor of up to 8 compared with the conventional single-channel ad hoc network architecture.

Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks

Applications, systems and methods for permitting simultaneous use of a file by two or more computers over a network may include storing the file locally in a local storage device associated with a local computer; providing access to the file by at least one remote computer which is connectable to the local computer via the network, and wherein at least one of the computers is connectable to the network through a firewall element. The file may be stored in at least one remote storage device associated with the at least one remote computer, respectively, and versions of the file contained on the one or more remote storage devices are synchronized with that on the local device by transmitting over the network connecting the one or more remote storage devices with the local device, at least one of Delta files and Inverse Delta files between the remote storage devices and the local storage device. A method of remotely observing computer activity on a second computer remote with respect to a first computer is also provided. Further, file sharing systems and methods are provided for sharing files among computers.

Managed peer-to-peer applications, systems and methods for distributed data access and storage

The disclosed embodiments include system and method for routing communications over a communications network. In one embodiment, a determination is made as to whether to establish a communication along a communication path based on network performance information. The disclosed embodiments provide several alternatives for establishing the communication and improving communications along the communication path in response to a determination that at least one network node along the communication path is impaired or congested.

System and method for routing data on a packet network

A method for data broadcast over a network includes receiving at a virtual bridge a data packet to be flooded over the network, and passing the data packet from the virtual bridge to a multicast-capable router, along with a broadcast indication. Responsive to the broadcast indication, the router determines a group of destination addresses to which the packet should be multicast, and creates copies of the packet for transmission over the network to the destination addresses in the group.

Virtual private LAN service using a multicast protocol

Systems and methods for remote access of network-enabled devices that provide seamless, firewall-compliant connectivity between multiple users and multiple devices, that allow collaborative operations by multiple users of remote devices, that allow point to multipoint control of multiple devices and which allow rapid, secure transmission of data between remote users and devices. In general terms, the system includes at least one connection server, and at least two computers operatively coupled to the connection server via a public or global network. In an example where at least one client computer is operatively connected to at least one network-enabled device through a connection server via the public or global network, the connection server is configured to route control instructions from the client to the network-enabled device, and route data from the network-enabled device to the client.

Access and control system for network-enabled devices

An admission control and load balancing system controls admission of packet streams or calls to a network and balances the packet traffic across the network, improving quality of service. The system includes a central database which stores information including cost data associated with individual paths and links across the network. A processor, in communication with the database, coordinates the admission control and load balancing decisions, and updates of the database cost data to reflect the dynamic network conditions, based on input from appropriate data sources. In one embodiment, referred to as the exact algorithm, the database is consulted by the admission control points or gatekeepers prior to admitting each arriving packet stream, and the database contents are updated call-by-call to reflect the allocation of resources to each admitted stream. In another embodiment, referred to as the inexact algorithm, control decision as well as database updates occur on a periodic rather than on a call-by-call basis to promote better scalability. In this embodiment, the processor periodically calculates admission decisions based on cost data in the central database. These admission decisions are then periodically forwarded to a satellite database associated with each gatekeeper, for storage and use in admission decisions until the next update epoch.

Method and apparatus to provide centralized call admission control and load balancing for a voice-over-IP network

A method and apparatus to control call admission to a packet-based network and achieve load balancing over a packet-based network includes at selected times generating and sending a path status message along a defined path, such as an MPLS path, through the network. As the message travels along the path, a cost metric field within the message is updated. The cost metric may reflect available bandwidth, or percentage utilization of the aggregate bandwidth, on the most congested (bottleneck) link in the path that it tracks. The cost metric is determined for each link at a data measuring point, such as individual routers, along the path. The optimum path between two gateways is determined, and further packet streams are routed onto the optimum path. In the event that no paths between a source and destination gateway meet predetermined utilization criteria, a packet stream block indicator is set which shows a requesting edge router that no paths are currently available for a packet stream requesting routing between particular source and destination gateway. The path utilization status message may be generated alternately in routers or in a master gateway. In either case, the messages are sent and the status of the network is determined in a distributed fashion at selected times, such as a regular timed interval.

Distributed call admission and load balancing method and apparatus for packet networks

A system and method are described for assigning downstream and upstream communication pathways in broadband access networks, such as networks based on the hybrid fiber-coax architecture. In the upstream direction, frequency channel and time slot assignments use a packing opposite methodology, which is dependent on the type of service request. The system assigns the lowest time slot in the lowest frequency available for a DSO service request and the highest time slot in the highest frequency which has the next four contiguous time slots available for an H0 service request. To optimize upstream bandwidth efficiency, a H0 channel occupying the space of four contiguous time slots is used to carry up to six simultaneous voice conversations. A method is described that governs such use of H0 channels by NIUs according to their offered loads. In the downstream direction, network interface units are automatically assigned frequencies in response to the expected load across the available frequency channels and are made to spread evenly the load across all downstream frequency channels. In one embodiment, assignments are based upon each individual network interface unit load, each network interface unit group load, the capacity of each network interface unit group and the blocked load. An assignment will be made to the group having the maximum idle capacity, i.e., the group which has the greatest blocked load differential. That is, assignments are made if moving an individual NIU from a first NIU group to a second NIU group results in a blocked load differential greater than the cost ratio R, where R represents the cost of moving an NIU divided by the cost.

Frequency channel and time slot assignments in broadband access networks

Critical national infrastructures for power, finance, transportation, and other basic resources rely on information and telecommunications networks (voice, data, Internet) to provide services and conduct business. While these networks tend to be highly reliable, disasters may lead to extended outages requiring days/weeks to repair. These outages can cause loss of emergency services, financial transaction failures, power distribution and transportation inefficiencies, and other malfunctions, resulting in inconvenience, financial ruin for individuals or businesses, or even loss of life. In this paper, we describe the life cycle of a disaster first and then present an approach for modeling information network disasters and their impact on other national infrastructures. Central to the approach is a simulation engine that Bell Labs has developed. The engine uses publicly available data (e.g., demographics, census, infrastructures) and, coupled with Bell Labs' network design and operational expertise, it effectively models network performance. This is particularly useful in the analysis of failure scenarios during and after a network disaster, providing insight for improving networks, procedures, and policies.

A network survivability model for critical national infrastructures

A method and apparatus for analyzing current voice call quality in an IP network before allowing a new voice call to enter therein. Circuitry in each gateway between a PSTN and the IP network obtains information from the IP network regarding the quality of voice call traffic being transmitted from one gateway to another gateway. A parameter is calculated by the circuitry based on this information. This parameter is compared to predetermined thresholds to guarantee acceptable quality for a new voice call that is attempting to enter the IP network. The circuitry includes three circuits. A first circuit passes voice call data to the IP network. A second circuit polls the IP network about traffic information transmitted therein. A third circuit processes the polled information to determine whether the voice call data is to be accepted by the IP network.

David J. Houck

Papers

Method and apparatus to provide centralized call admission control and load balancing for a voice-over-IP network

Distributed call admission and load balancing method and apparatus for packet networks

Frequency channel and time slot assignments in broadband access networks

A network survivability model for critical national infrastructures

Method and apparatus for management of voice-over IP communications