Simulations and Prototyping of the LHCb L1 and HLT Triggers

The Level 1 (L1) and High Level Triggers (HLT) for the LHCb experiment are software triggers which will be implemented on a farm of approximately 1800 computers, connected via a Gigabit LAN with a bandwidth capacity of 7.1 GB/s and containing some 500 Ethernet links. The architecture of the readout network must be optimised to maximise data throughput, control data flow and minimise errors. We report on the development and results of two independent software simulations which allow us to evaluate the performance of various network configurations. We also describe the construction of two hardware testbeds of the LHCb L1 and HLT trigger system, which allow microscopic and macroscopic study of network and switch behaviour.