Nortel Networks Corporation

Marconi UK Intellectual Property Limited

Martin Sabry

Graeme A Gibbs

Rade Gvozdanovic

Cho Y Tang

Paul Anthony Kirkby

Dave Lewis

John E Midwinter

A method and apparatus for managing a length of optical fiber by housing the length of optical fiber in a duct, the length of optical fiber being so coiled as to extend along the duct and the length of optical fiber being connected to a plurality of fiber-joining devices positioned along the duct. The fiber-joining devices are contained in modules which are removably attached to the outer periphery of the duct.

Method of and apparatus for managing a length of optical fibre

Connection admission control to an ATM network from a plurality of sources sharing a common virtual channel connection in which information packets are carried in cells is effected by determining whether that connection requires the transmission of a single packet per cell, partially filled cells containing more than one packet or fully filled cells. Where a single packet is to be transmitted per cell, the bandwidth requirement is calculated via a first algorithm. Where fully filled cells are to be transmitted, the bandwidth requirement is calculated via a second algorithm. Where partially filled cells containing more than one packet are to be transmitted the bandwidth requirement is calculated via an interpolation between the two algorithms. This provides a more accurate measure of equivalent bandwidth and thus facilitates efficient use of network resources.

Providing connection admission control in a communications network

In order to provide price information to customers quickly a fast reflector switch is used. This helps to ensure that price information provided to customers is as up-to-date as possible. To determine a price for use of a particular route in a communications network, the available resources at each node in that route are assessed. The most congested node in that route is selected and a price determined on the basis of the available capacity at that node. This price is then delivered to the customer via the fast reflector switch. In another example, the average amount of available resources at each node in the route is determined over a specified time period. The standard deviation of the resource level values at each node over the specified time period is also determined. A price is then set on the basis of the sum of the average amounts and the sum of the standard deviations. In this way a price which takes into account recent variation in traffic levels as well as average traffic levels is provided.

Pricing mechanism for resource control in a communications network

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

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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Cambridge, United Kingdom

Martin Sabry