The hardware
Grids must be built "on top of" hardware, which forms the physical infrastructure of a grid - things like computers and networks. This infrastructure is often called the grid "fabric".
Networks are an essential piece of the grid "fabric". Networks link the different computers that form part of a grid, allowing them to be handled as one huge computer.
Networks are characterized by their size (local, national and international) and throughput (the amount of data transferred in a specific time). Throughput is measured in kbps (kilo bits per second; where kilo means a thousand), Mbps (M for mega; a million) or Gbps (G for giga; a billion).
One of the big ideas of grid computing is to take advantage of ultra-fast networks. This idea allows us to access globally distributed resources in an integrated and data-intensive way. Ultra-fast networks also help to minimize latency: the delays that build up as data are transmitted over the Internet.
Grids are built "on top of" high-performance networks, such as the intra-European GEANT network, which has 10Gbps performance on the network "backbone". This backbone links the major "nodes" on the grid (like national computing centres).
One level down from the "backbone" are the network links, which join individual institutions to nodes on the backbone. Performance of these is typically 1Gbps.
A further level down are the 10 to 100Mbps desktop-to-institution network links.
BUT WHAT DOES "HIGH PERFORMANCE" MEAN?
Performance is measured in flops. A flop is a basic computational operation - like adding two numbers together. A Gigaflop is a billion flops, or a billion operations.
Want more? Take a look at Internet Backbone Networks in the Atlas of cyberspaces. Or check out the Top500 high-performance networks and grid nodes.
