Abstract: A datagram network is operated by placing a group address in the source address field of the datagram. Nodes within the datagram network forward the datagram in dependence on the contents of the source address field. This provides many of the scalability advantages offered by Multiprotocol Label Switched (MPLS) networks without introducing the overheads caused by connection set-up in MPLS networks. The method can also easily provide different quality of service levels to different types of packets and is especially useful in providing Virtual Private Networks across a shared internetwork such as the public Internet.

Abstract: Routing of packets is controlled in a connectionless routing protocol network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by data held in packet switching nodes located along said routing path, may be directed in the infrastructure for a given network address.

Abstract: In a packet switched network, first said network address are allocated to a first mobile node being served via a communications link by a first access node, at least a first routing path in related infrastructure being directed to the first access node for the first network address. Routing in said infrastructure is altered when the first mobile node receives service from a second access node, such that at least a second routing path in the infrastructure is directed to the second access node for the first network address, the second routing path being defined at least in part by one or more host-specific routing entries. During a period of subsequent inactivity, the one or more host-specific routing entries are removed from the infrastructure such that the mobile node has no current routing path.

Abstract: Control messages constructed in accordance with a first communications protocol for use in a communications network each include a first address identifier having a format defined by the first protocol. The control message is processed to derive a second address identifier having a format defined by a second communications protocol. The control message is re-formatted for transmission, in accordance with the second protocol, to a network system associated with the second address identifier.

Abstract: Routing of packets is controlled in a communications network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by data held in packet switching nodes located along the routing path, may be directed in the infrastructure for a given network address.

Abstract: Packets are routed in a communications network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by data held in packet switching nodes located along the routing path, may be directed in the infrastructure for a given network address. Different types of routing updates are used in a single routing domain.

Abstract: Packets in a packet switching network are routed along a routing path defined by data held in packet switching nodes. One or more network addresses are assigned to a first access node as home addresses. A first home address is allocated to a first mobile node with at least one routing path being directed to a first access node for that first home address. Routing in the packet switched infrastructure is altered when the first mobile node receives service from a second access node by transmitting routing update messages to a limited subset of localized packet switching nodes such that at least one routing path in the infrastructure is directed to the second access node for the first home address. Routing in the infrastructure is subsequently altered such that at least one routing path is directed to the first access node for the first home address, and the first home address is allocated to a second mobile node served by the first access node.

Abstract: Routing of packets to a mobile node in a packet switching network is controlled. Routing the packets comprises generating first routing protocol data for a network address used by a mobile node of the network, the first routing protocol data specifying a characteristic of a first route passing through a first access node of the network, the first access node serving the mobile node via a communications link, and in response to the mobile node receiving service from a second access node, generating second routing protocol data for the network address, by a routing defining process involving transmitting directed routing update messages to a limited number of the packet switching nodes. The second routing protocol data specifies a characteristic of a second route passing through the second access node such that the first and second routing protocol data are held in different sets of packet switching nodes.

Abstract: The invention provides a method, data processing system and software for generating address identifiers for use in a communications network. The method comprises the step of processing a first address identifier constructed in accordance with a first communications protocol; and the step of constructing a second address identifier, from said first identifier, in accordance with a second communications protocol. The first communications protocol may be protocol Simple Mail Transfer Protocol (SMTP) and the second communications Session Initiation Protocol (SIP). The invention enables messages to be sent to a SIP URL derived from an SMTP email URL. In the event that the SIP URL is invalid, or unregistered the SIP message is diverted from a SIP defined destination URL address identifier to a corresponding SMTP defined destination URL address identifier for the same user or end system.

Abstract: In a mobile packet network, data is transmitted concurrently from two base stations to a mobile node, for example during handover.

Abstract: The present invention provides a method of, computer programs for and apparatus adapted to operate a communications network to determine membership of a group of access nodes of the communications network with which there is a relatively high probability that a mobile node will be associated after the mobile node has been associated with a first access node, access nodes being linked to other access nodes via data communications links, the method comprising:

Abstract: The present invention provides a method of, computer programs for and apparatus adapted to operate a communications network to generate data defining a forwarding tree for the transmission of messages in said network, said method comprising:

Abstract: A method of controlling routing of packets in a packet switched network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by routing entries held in packet switching nodes located along said routing path, may be directed in said infrastructure for a given network address, said method comprising:

Abstract: A method of controlling routing of packets in a communications network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by data held in packet switching nodes located along said routing path, may be directed in said infrastructure for a given network address, said method comprising:

Abstract: A method of controlling routing of packets in a communications network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by data held in packet switching nodes located along said routing path, may be directed in said infrastructure for a given network address, said method comprising:

Abstract: A method of operating a datagram network is disclosed. The method involves placing a group address in the source address field of the datagram. Nodes within the datagram network forward the datagram in dependence on the contents of the source address field. This provides many of the scalability advantages offered by Multiprotocol Label Switched (MPLS) networks without introducing the overheads caused by connection set-up in MPLS networks. The method can also easily provide different quality of service levels to different types of packets and is especially useful in providing Virtual Private Networks across a shared internetwork such as the public Internet.

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: The invention provides a method, data processing system and software for generating address identifiers for use in a communications network. The method comprises the step of processing a first address identifier constructed in accordance with a first communications protocol; and the step of constructing a second address identifier, from said first identifier, in accordance with a second communications protocol. The first communications protocol may be protocol Simple Mail Transfer Protocol (SMTP) and the second communications Session Initiation Protocol (SIP). The invention enables messages to be sent to a SIP URL derived from an SMTP email URL. In the event that the SIP URL is invalid, or unregistered the SIP message is diverted from a SIP defined destination URL address identifier to a corresponding SMTP defined destination URL address identifier for the same user or end system.

Abstract: The invention provides a method, data processing system and software for processing control messages constructed in accordance with a first communications protocol for use in a communications network. Each control message includes a first address identifier having a format defined by the first protocol. The method comprises the step of processing said control message to derive a second address identifier from said first identifier, said second identifier having a format defined by a second communications protocol; and, the step of re-formatting said control message for transmission, in accordance with said second protocol, to a network system associated with said second address identifier. The first communications protocol may be Session Initiation Protocol (SIP) and the second communication protocol Simple Mail Transfer Protocol (SMTP).

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.