PFLDNet Workshop February 2003 R. Hughes-Jones Manchester TCP: Extensions or A New Protocol ? A User View Point Richard Hughes-Jones The University of Manchester Workshop on Protocols for Fast Long-Distance Networks Panel 2

PFLDNet Workshop February 2003 R. Hughes-Jones Manchester uEuropean VLBI Network includes Europe + China + Ukraine + South Africa uThe amount of detail seen depends on the size of the telescope – hence VLBI uSensitivity of the network depends on the rate at which the data recorded uProof of Concept: 5 telescopes connected at 1 Gbit/s of user data this year. (10Gb) uData Unusual: Does not matter is lose a small part so long as it is know it is lost uOther VLBI systems looking gat 30 Gbit/s per telescope (dark fiber / private SDH) Radio Astronomy: Very Long Base Line Interferometry

PFLDNet Workshop February 2003 R. Hughes-Jones Manchester uHEP experiments will need to move bulk data at high rate 24/24. uPlanning on 2.5 Gbit/s going to 10 Gbit/s from Tier 0 to all large Tier 1 sites. uOne LHC experiment will start trying to move 1 TByte/day of Monte Carlo data to CERN starting this November uOK its only 100 Mbit/s but there are 4 experiments and real data will be going in the other direction. uOther grid users of bulk data include: remote molecular visualisation, high definition TV for remote use of microscopes, tele medicine … Particle Physics

PFLDNet Workshop February 2003 R. Hughes-Jones Manchester Some “User” Requirements uHigh Throughput uReliable bulk data transport: bit-wise correct for many users Minimum known loss for others uHigh throughput should start quickly – eg for http – TCP QuickStart ? uIt should be fair: To other users Long RTT should not be penalised Nor should MSS limit one* uShould be responsive to changes in Available bandwidth (both increase and decrease in rate) So should be able to make efficient use of eg LBE QoS uDeployment – evolution or revolution or both? uGeneral acceptance – IETF involvement u* Maybe think HW changes too

PFLDNet Workshop February 2003 R. Hughes-Jones Manchester Some Points for Discussion uWhat’s the current work on new protocols? uWhat’s the investment likely to be ? – Remember OSI TP4 ?? uCan experience gained from NS and live tests of new stacks help choose the best way forward – I hope so ! uAlternatives to TCP end-to-end UDP-based solutions eg Tsunami Depot staging (cf BITNET) iSCSI – this would be real disk-disk … uHardware Assists What is the progress at the moment? Can flexibility be included RDMA uCan a protocol design make for very efficient HW assist? uGiven a Lambda lightpath circuit and BERs, why run TCP on this? FEC OK? uOver to you …