ATM Testbed

General Description

Most of the equipment on the ATM testbed was funded from an HEFC Special Equipment Grant, with generous support from ECI Telematics.

The resources available on the testbed network are shown in the figure below. Six ATM switches are available, with enough 155Mbps interfaces to fully connect them. Traffic enters the network at one of the eight 155Mbps fibre optic ports. A variety of test equipment can be connected to these ports, including network analysers, PCs with ATM NICs, Ethernet traffic sources and a selection of video equipment. Remote access is possible to the switch nodes (for configuration and for gathering statistics), to the two network testers/analysers and to the attached PCs. These remote facilities are used to perform experiments within the Virtual Laboratory provided by the Trilogy project.

Although shown here in its fully interconnected form, the network topology can be altered to suit particular activities. Since the network is entirely dedicated to research and carries no user traffic, it can be reconfigured at will. 

Remote Experiments

The two ATM analysers have traffic generation and capture facilities. Deterministic ATM cell sequences can be generated, transmitted into the network and then captured as they emerge from the network. Analysis of the captured cell data gives statistics on cell delays, delay variation and inter-cell arrival times.

Remote access to the switch nodes allows VCs to be created or destroyed and for the buffering, scheduling and policing strategies at each switch to be modified. This allows studies of different network resource allocation techniques and their effects on quality of service.