TobyRodwell wants to know what is the cause of these single high delay events. My assumption is that it has to do with the end-hosts and not the network inbetween. It could be an issue with timestamping and local buffers (NIC, kernel, user-level) See the discussion on pert-discuss for more info. Ralf Kleineisel suggests adding a second NIC from a different manufacturer to the IPPM boxes which have such anomalies and to compare results to find out if there could be a problem with the NIC/driver. However this will not rule out any problems on the application/kernel level.

-- ChrisWelti - 03 Mar 2005