Abstract: Data is transferred between mobile or fixed end devices connected to respective base stations. A first session identifier (session ID) is selected from a first array for sessions originating from an initiating end device. Data is transferred as a plurality of packets each of which contains the first session ID to a remote end device connected to a remote base station, the remote base station being configured to: allocate a second session ID from a second array, map to one another the said first and second session IDs, and, a forward the said second session ID to the remote end device. In this way, the mapping between session IDs need not be stored in the end devices, allowing for a session to be handed over from one end device to another end device where both end devices are connected to the same base station.

Abstract: Nodes in a datagram network are arranged to route datagrams in dependence on a batch start time parameter contained in the header of datagrams belonging to a batch. A network operator is thus able to offer a service that is connection-oriented at the batch level, without necessarily being connection-oriented at the message level. This is advantageous to the network operator since it allows the packet flow generated by the user to be re-routed during the transmission of the message. The user can arrange those datagrams which are required to be delivered from the network in the same order as they are supplied to the network into batches. In that way, the user is not adversely affected by route changes made by the network operator in order to improve the performance of the datagram network.

Abstract: A method is provided for more efficiently transmitting data from a server computer to a client computer over a communications network, the nodes of which are capable of providing two classes of transmission quality. Data is transmitted using the high priority class until a local cache at the client computer is filled to a certain upper threshold, at which point the data is transmitted using the low priority class. If the local cache at the client computer subsequently reaches a lower threshold then the transmitted reverts to the use of the high priority class. The communications network may be connection-based (e.g. ATM) or connection-less (e.g. the Internet).

Abstract: A datagram network is disclosed. Nodes in the datagram network are arranged to route datagrams in dependence on a batch start time parameter contained in the header of datagrams belonging to a batch. A network operator is thus able to offer a service that is connection-oriented at the batch level, without necessarily being connection-oriented at the message level. This is advantageous to the network operator since it allows the packet flow generated by the user to be re-routed during the transmission of the message. The user can arrange those datagrams which are required to be delivered from the network in the same order as they are supplied to the network into batches. In that way, the user is not adversely affected by route changes made by the network operator in order to improve the performance of the datagram network.

Abstract: A new approach to providing both bounded-delay and best-effort operation in a packet network node is described. The bounded-delay mode is capable of providing a firm end-to-end delay bound, but in contrast to the combination of RSVP and Guaranteed service proposed within the IETF, it does this with minimal complexity. Network nodes are provided with dual packet buffers associated with bounded delay and best effort classes of service respectively. Appropriate dimensioning, if necessary enforced through CAC methods, ensure that packets admitted to the bounded delay buffer are provided the firm delay bound. CAC methods are described which are applicable for packet flows as small as a single packet. A means is also offered for removing the traditional network signalling phase. A related architecture for use with hosts is also described.

Abstract: A method of transmitting across an ATM network a connectionless datagram in a cell structure having the form of a plurality of ATM cells the first cell of which carries in its payload the routing information of the connectionless datagram, and wherein at an intermediate node of the network a connectionless routing function is carried out on said first cell with the remaining cells remaining in the ATM layer.

Abstract: An ATM network includes a set of interconnected switches and gateways. The ATM network is capable of providing both a conventional connection-oriented service or a connectionless service. Where a connectionless service is required, at the input interface, source and destination addresses are inserted into the header and fields in the header are set to values which indicate that a connectionless service is required and whether or not additional processing is also required. At each node between the input interface and the output interface, where a connectionless service is required, each ATM cell is routed in accordance with its source address and destination address and/or a routing table which is set up by routing protocol or network management.

Abstract: A method of reserving resources in an internet is disclosed. The method provides an improved process for use in relation to large scale shared-tree multicast environments since its use results in a reduction in path state in the routers (A-E, R1-R6) in the internet. The method involves the sending of path characteristics upstream from receivers (H1-H7) to senders (H1-H7), the routers in between combining path characteristics from different sources downstream of them. Reservations are subsequently made on the basis of the combined path characteristic data, the nature of the sender's traffic and the end-to-end quality of service required by the sender.

Abstract: Apparatus for generating of a comb having a large number optical teeth and comprises an optical loop (3) including an optical amplifier (5) a frequency shifter (4) and an optical filter (6). A signal from a laser (9) is partially coupled into the loop by a coupler (7) such that a part of it is output at output port (10). The signal in the loop (the feedback signal) is amplified by the amplifier (5) and frequency shifted by the frequency shifter (4) and is then partially coupled out of the loop by coupler (7). The part coupled out of the loop (the output signal) exits via output port (10). This process is repeated to produce the desired number of output signals exiting via output port (10). The signal from the laser (9) may be continuous or pulsed.

Abstract: A method and apparatus for transmitting information comprises a signal generator (1) for continuously generating a pair of optical signals (f1, f2). These signals are similarly modulated in a modulator (5) with information to be transmitted and are combined with their polarizations substantially orthogonal. The combined signals are transmitted with the portions of each signal modulated with the same information being transmitted together down an optical fiber.