British Telecommunications Public Limited Company

British Telecommunications Corporation

Philip L Eardley

Trevor Burbridge

Robert J Briscoe

Matthew D Walker

Alan P Smith

Simon P A Ringland

Andrea Soppera

Robert Hancock

Gabriele Corliano

Jochen Eisl

Andrej Mihailovic

Hui Min J Tay

Methods and apparatus are disclosed for obtaining diagnostic test results in respect of network elements in a network, the test results being obtained from a population of probes associated with network elements. The method comprises receiving a first-stage set of probe reports comprising, in respect of probes in an initial subset, a test result and metadata, each test result indicating a state of the network element associated with the probe; identifying a specific subset of probes in the initial subset wherein the test results from the probes in the specific subset satisfy a predefined condition; determining a subsequent subset based on the metadata of the probes in the specific subset; and triggering the probes in the subsequent subset to provide a second-stage set of probe reports comprising test results indicating states of network elements associated with probes in the subsequent subset.

Diagnostic testing in networks

The invention relates to a method of controlling packets in a data packet network, the method comprising the steps of: a source node sending a first set of packets to a receiver node over the data packet network via an intermediate node, wherein the first set of packets are marked as being of a class of service preventing them from being forwarded to the receiver node if a packet queue exists at an intermediate node; the source node receiving an acknowledgement of a received packet of the first set of packets from the receiver node; and the source node sending a second set of packets to the receiver node over the data packet network.

Data packet network

Methods and apparatus are disclosed for processing data items received at a network element in a communications network. In particular, methods and apparatus are disclosed for processing data items such as packets received at a network element such as a router or other such packet-forwarding network element () from a source (') and which are intended to be forwarded towards an intended receiver (&#x2032;) in a communications network such as a network operating according to the Internet Protocol.

Processing data items in a communications network

The invention includes a network node, and a method of controlling the network node in a data packet network, wherein the method comprising the steps of: receiving a first data packet from a first external network node; analysing the first data packet to determine if it is of a class of service deemed to be queuable or unqueuable; and, if it is queuable, sending the first data packet to a second external node via an intermediate node, wherein the first data packet is reclassified to be of the unqueuable class of service such that the intermediate node should not forward the first data packet to the second external network node if a packet queue exists at the intermediate node.

Methods and apparatus are disclosed for analyzing network performance of a network comprising a plurality of network nodes. The method may comprise: obtaining a plurality of probe measurements in respect of a target node, the probe measurements resulting from probe test-messages being sent via different network paths to said target node and relating to a network performance characteristic in respect of the paths taken by the respective probe test-messages and probe response-messages associated therewith and being dependent also on local processing of the respective probe test-messages at said target node; determining respective measures of unexpectedness in respect of the probe measurements; comparing said respective measures of unexpectedness and in dependence on the comparison, assigning a weighting in respect of said target node; and determining a network performance analysis measure in dependence on at least one probe measurement and on the weighting.

Analysis of network performance

Methods and apparatus are disclosed for analyzing network performance of a network comprising network nodes. The method may comprise: obtaining probe measurements by sending probe test-messages via a path from a testing node to a first target node, and also by sending probe test-messages via a path from the testing node via the first target node to a subsequent target node, the probe measurements relating to a network performance characteristic in respect of the paths taken by the probe test-messages and probe response-messages associated therewith and being dependent also on local processing of the probe test-messages at the respective target nodes; comparing the probe measurements; in dependence on the comparison, assigning a weighting in respect of the first target node indicative of whether it is deemed likely to be providing reliable or unreliable results; and determining a network performance analysis measure dependent on the probe measurements and on the weighting.

Methods and apparatus are disclosed for analyzing performance of a network. The method may comprise: obtaining first and second probe measurements resulting respectively from a test-message being sent from a first node and having a second node as the target thereof, and from a test-message being sent from the second node and having the first node as the target thereof, associated probe response-messages triggered by receipt and local processing of the test-messages at the target nodes thereof being sent back to the senders of the test-messages, the measurements relating to a network performance characteristic in respect of the paths taken by the test-messages and response-messages, and being dependent also on the local processing of the test-messages at the respective target nodes; comparing the measurements, assigning a weighting in respect of at least one of the nodes dependent on the comparison; and determining a network performance analysis measure according to a function dependent on at least one of the probe measurements and on the weighting.

Methods and apparatus are disclosed for analyzing network performance in relation to a network portion comprising a group of nodes. The method may comprise: obtaining probe measurements in respect of a plurality of target nodes in the group, respective probe measurements each resulting from a probe test-message being sent via a network path from a testing node to a target node and an associated probe response-message triggered by receipt and local processing at the respective target node of the probe test-message being received via a path from the respective target node by the testing node, the respective probe measurements relating to a network performance characteristic in respect of the paths taken by the respective probe test-messages and the probe response-messages associated therewith and being dependent also on the local processing of the respective probe test-messages at the respective target nodes; comparing probe measurements obtained in respect of different target nodes in the group, and in dependence on the comparison, assigning a weighting in respect of at least one of the nodes; and determining a network performance analysis measure in relation to the network portion according to a predetermined function dependent on the probe measurements and on the weighting.

Congestion in respect to a network element operable to forward data items in a telecommunications networks, and in respect to a processing element operable to process requests for service is signaled. In either, the element is operable to perform its processing function at up to a processing rate which is subject to variation, and has a queue for items awaiting processing having a counter associated therewith which maintains a count from which a queue metric is derivable. A method comprises: updating the count at a rate dependent on the processing rate; further updating the count in response to receipt of items awaiting processing; and signalling a measure of congestion in respect of the element in dependence on the queue metric; then altering the rate at which the count is being updated and adjusting the counter whereby to cause a change in the queue metric if the processing rate has changed.

Signalling congestion

Methods and apparatus for controlling the forwarding of a flow () of data units across a network from a sender node () to a receiver node () via at least one intermediate node (), the data units each having one of a plurality of different types of class indication associated therewith, each type of class indication providing, to an intermediate node currently processing the data unit with which the class indication is associated, an indication denoting a particular class of treatment, selected from a plurality of different classes of treatment, according to which the data unit is to be processed by that intermediate node, such that different proportions of the data units of the flow are forwarded as different sub-flows each comprising data units having class indications of different types thereby providing indications denoting different classes of treatment.

Multi-class data transport

The present invention provides a method and system wherein congestion information is taken from a lower level in the protocol stack and used for congestion marking in a higher layer. In particular, the method and system of the invention from a first aspect provide for congestion information in the lower layer to be generated downstream at a congested node, and to be fed back upstream to a source node. The source node then passes the congestion information, or information derived therefrom, up to the corresponding network element responsible for higher layer functions in the protocol stack, where higher level congestion marking can then be performed in dependence on the received lower level congestion information. Thus, congestion information from the lower layer which can typically be generated earlier before significant congestion occurs can be used in higher layer congestion control functions. Preferably the lower layer is the data link layer, and the higher layer is the network layer.

Method and system for congestion marking

A method of call control in which a first communications network, detecting calls directed to a destination in the first network; redirects at least some of the calls to a destination in a second network (e.g. on no answer from the destination in the first network). The first communications network obtains from a client on a terminal associated with the destination in the second network a value for the time delay before a call to the destination in the second network is redirected in the second network on no answer to an alternative destination and sets a delay period to a value less than the value of the time delay obtained from the client. When one of the plurality of calls redirected to the second network is not answered in the second network within the delay period, the first communications network redirects the call to an alternative destination associated with the first network.

Call control

A method of routing packets in a packet network is disclosed. The packet network includes a chain of packet nodes, the chain comprising a first and second access node for communicating with one or more mobile nodes and one or more intermediate packet nodes providing a path interconnecting the first and second access nodes. Previous methods are inefficient and lead to additional overhead. The method comprises the steps of: installing, in said intermediate packet nodes, first routing data defining a first routing path in one direction along said chain to a mobile node via said first access node and second routing data defining a second routing path in the opposite direction along said chain to said mobile node via said second access node; operating each of said intermediate packet nodes to: determine, on receipt of a packet destined for said mobile node, whether said packet is from another node on said chain or not; and a) if the packet is determined to be from a node not on said chain, copying the packet and routing said copy along one of said routing paths and routing said packet along the other of said routing paths; and b) if the packet is determined to be from another node on said chain, route said packet along said chain only in the direction in which it is currently travelling.

Method of routing packets in a packet network

A method of call control in which a first communications network, detecting calls directed to a destination in the first network; redirects at least some of the calls to a destination in a second network (e.g. on no answer from the destination in the first network). The first network then operates in two phases. In a first phase, for a group of calls redirected to the second network, the time delay before the call is answered in the second network is recorded. When a number of time delays have been recorded, a delay period is set to a value less than the maximum value of the recorded time delays. In a second phase, for a second group of calls redirected to the second network subsequent to the calls of the first group, when a call of the second group is not answered in the second network within the delay period, the call is redirected to a message service associated with the first network.

A telecommunications system includes a mobile network having a plurality of portable communication devices, and a fixed network which includes a signaling agent, a plurality of directory agents, and a plurality of spaced apart attachment points to which the mobile network can attach. In use, each directory agent stores a routing table for routing data to a respective mobile communication device associated with that directory agent. When the point of attachment of the mobile network changes, the mobile network sends a change-of-address message to the signaling agent. In response, the signaling agent is configured to forward the change of address to each directory agent, so that each can update its routing table to take into account the changed point of attachment of the mobile network. Because a signaling agent is provided, each portable device need not itself notify its directory agent when the mobile network moves, and the amount of signaling between the mobile network and the fixed network when the mobile network moves is reduced.

Growing community of inventors

Ipswich, United Kingdom

Philip L Eardley