British Telecommunications Public Limited Company

British Telecommunications Corporation

Gabriele Corliano

Ben Strulo

Robert J Briscoe

Marc Wennink

Philip L Eardley

Peter Hovell

Hui Min J Tay

Marc Wennick

Mark Wennink

Robert John Briscoe

Philip Laurence Eardley

In embodiments of the invention when a session request is received the value assigned to that session is compared to present congestion costs in the network at the present time. If the value of the session exceeds the cost then the session is accepted; otherwise it is rejected. It is possible to show mathematically that, provided this strategy is used for all session requests, then, when demand exceeds supply for a given resource, the congestion measurement for that resource rises to become equal to its shadow price. Here, in a model of a capacity constrained network, the shadow price of a capacity constraint is the cost to other users of using one unit of capacity. Congestion measurements can therefore be used to provide a 'cost' (to other users) of admitting the flow to the network, which can then be compared against the 'value' (to the network operator) of admitting the flow during the admission control evaluation. Additionally, this &#x201c;cost&#x201d; vs. &#x201c;value&#x201d; comparison can be used for path selection, as well as any other resource management decision. For example, in particularly preferred embodiments a session is not only admitted based upon the cost value comparison, but is also assigned to a particular path which maximizes value minus cost.

Admission control in a packet network

A method and system is described that adjusts the allocated capacity of a network between services, or service or traffic classes, in dependence on a congestion-influenced shadow price indication in respect of each service or class. In this respect, instead of viewing the congestion price as a cost of using already allocated unit of capacity, such a shadow price indication can be viewed as an indicator of the value obtainable from allocating an extra unit of capacity to a service or class. By so doing the shadow price indication becomes a factor to be taken into account in deciding on capacity allocation between services or classes, with a high shadow price indication for a service or class indicating that additional value would likely be obtained by allocating an additional unit of capacity to the service or class.

Capacity adaptation between services or classes in a packet network

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

Methods and systems for providing information relating to congestion at a network element caused by data units intended to be forwarded across a telecommunications network by the network element, the apparatus comprising: load-data receiving means for receiving load data relating to data units intended to be forwarded by the network element; rate-data obtaining means for obtaining data indicative of a configurable rate; first and second registers for storing first and second metrics; first and second updating means operable to update the metrics in said first and second registers in dependence on said load data and on the configurable rate; and a congestion indication provider operable to provide indications of congestion in dependence on the metrics stored in the registers; said apparatus being configured in such that it may provide behavior equivalent to a virtual queue marking scheme by virtue of a minor modification to hardware provided for Single Rate Three Color Marking.

Methods and apparatus for providing congestion information

The invention provides a coordination layer of coordinating entities provided intermediate the admission control interfaces of the transport network domains, and any QoS signaller which signals QoS requests on behalf of the application layer. The coordination layer acts to distribute an admission control request across the multiple transport network domains by the use of coordination request messages containing the admission control request being forwarded through the coordination layer of coordinating entities. At each coordinating entity the admission control request is passed on to the admission control interface of the transport network which the coordinating entity serves, and an admission control response obtained. This admission control response is then combined with admission control responses from the other domains which are propagated through the coordination layer via coordination messages. The result is that the coordination layer acts to combine the various admission control responses into a combined response, which can be provided back to the QoS signaller (or other requesting entity). Thus, coordination of admission control across multiple transport network domains is achieved, without a QoS signaller having to contact each individual domain.

Growing community of inventors

Ipswich, United Kingdom

Gabriele Corliano