Nortel Networks Corporation

Rade Gvozdanovic

Graeme A Gibbs

Martin Sabry

Cho Y Tang

A flow of packet or cell-based communications traffic is monitored by: setting a first time interval over which measurements are to be made; counting number of packets flowing during that time interval and using the count to derive parameters which are indicative of the traffic meeting a sustained cell rate (SCR) requirement. Use of this cell counting method rather than a per-cell computation of a generic cell rate algorithm (GCRA) reduces computation requirements in monitoring traffic. Preferably the cell count is used to derive a running difference between the counted number of packets and an expected number of packets.

Method of monitoring packet communications traffic

A connection admission controller determines whether to admit the requested connection according to whether admission would cause a bandwidth used to exceed a maximum bandwidth allowed. For determining the bandwidth used, an aggregate equivalent bandwidth of all connections is determined by determining a static approximation and a flow approximation, the flow approximation having a non-linear relationship to the number of connections. Using a non linear relationship enables the equivalent available capacity for a number of connections to be determined more accurately with less computational resources.

Derivation of equivalent bandwidth of an information flow

A traffic source emits packet-based traffic (ATM) carrying a plurality of variable bit rate calls. The traffic is managed by: measuring a parameter of the current traffic output from the source, using the measured parameter in a comparison with a parameter which is indicative of available capacity on the link; and providing a control signal for varying the operational state of the traffic source according to the comparison. The operational state can be varied by choosing a combination of a coding rate, selected from a range of coding rates, and selective use of silence suppression. A cell policing algorithm can be used, such as the GCRA. The system lowers transmission quality of voice traffic before lowering transmission quality of the data traffic, and uses silence suppression for voice traffic before using lower coding rates for the traffic source.

Method and apparatus for managing communications traffic

Admission control for a communications link involves maintaining a record at each end of the link of which channels on the link are free and allocating a free channel so that the probability of both ends allocating the same channel to different information flows is controllable. The record of channel identifiers is searched sequentially in different directions by the respective ends of the link to minimise the probability of simultaneous allocation before the records at each end are synchronised. New requests for admission to the link are allowed a different bandwidth threshold than requests for changes to existing connections already admitted to the link.

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Harlow, United Kingdom

Rade Gvozdanovic