Performance on the vBNS

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This report was written in December 1999. By the time you read it, it is probably out of date. Scroll to the bottom of the page for links to the up-to-date statistics.

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Performance between SLAC and sites connected to the vBNS network is important because many of the physicists collaborating on SLAC experiments are at universities connected to this network.

The vBNS network is typically uncongested ( present load can be seen on the vBNS weather map ) and hence we would not expect significant loss or delay in the delivery of packets.

The graph to the left shows the monthly packet loss between SLAC and 14 nodes at 11 sites. Not suprisingly the packet loss is low, typically less than 1%, and on only one occassion, in February 1999 did the packet loss exceed 2%, but given the other node at this site didn't experience similar loss it is reasonable to assume this was a problem with the LAN or the machine itself, not a problem with the WAN.

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The graph to the left shows the daily packet loss in November and the first two weeks of December. The packet loss is low with the occassional glitch.

These occassional glitches do not seem to coincide, hence the loss is not due to congestion in the vBNS backbone. hence the backbone network is not loaded, at least not for long.

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Only on 3 occassions was there packet loss at the same time to several sites (by eye). Packet loss was observed between other ESnet sites and vBNS that evening.

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We have previously noted observations regarding performance between SLAC and the University of Colorado at Boulder ( when discussing routing.


Other than the occassional glitch, performance between SLAC and sites connected to the vBNS is good. We would expect all network applications to perform well and certainly well enough for the usual day-to-day requirements of the physicists.

Further Information

Monthly packet loss for Sites in VBNS seen from SLAC

Monthly average RTT for Sites in VBNS seen from SLAC

Revised December 15 1999
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