Richard HJ's Web Site

This is Work in Progress - comments welcome ! The aim is to understand and compare data transfer rates and packet loss and packet re-ordering between CERN and RAL using a direct UKLight path. Details of the end hosts and Networks used are:

oplapro71 oplapro72 CERN	dual 1.5 GHz IA-64 Itanium 2 Broadcom Corporation NetXtreme BCM5701 Gigabit Ethernet
gftp0440 gftp0441 RAL	2.8 GHz Xeon Intel 1000/pro copper (82541E Gigabit Ethernet Controller)

UDPmon was used to measure the network performance:

• Request - response latency.
• Memory-memory transfer rates.
• packet loss
• packet re-ordering
• Inter packet Jitter.
• 1-way delay.
• cpu load & number of interrupts

Summary (so far)

First UDP throughput tests using 1500 byte MTU and 1472 bytes of user data between CERN & RAL

• CERN to RAL showed ~950 Mbit/s. but has a little packet loss (0.02%s). No re-ordering.
• RAL to CERN ~950 Mbit/s only for packets >800 bytes. Showed large losses ~40-50% loss for packets <600 bytes and spacing <5 us.
  Significant loss to 1% for all sizes - would kill TCP. No re-ordering