Degradation of Long Term WAN Performance

Les Cottrell, Last Update: January 24, 1997

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Performance between University node and ESnet nodes degraded badly in 1995-1996. Two metrics which can be used to illustrate this are the round trip response time for a ping packet, and the packet loss for ping pacekst. Examples of these metrics measured between SLAC and UC Davis are shown below.

In these plots the X axis has one point per day for the 180 days from 11/12/95 thru 5/15/96.

You can observe over a factor of 3 degradtion in the performance for the response time and packet loss metrics for this 6 month period. You can also observe that the weekend responses times and ping losses were lower than the corresponsing weekday measurements. Also the differences in the weekend and weekday response times and packet losses increased during this 180 day timeframe. The differences in the weekend and weekday measurements may indicate that the some of the cause of the problem is saturation of the links during the weekdays.

To provide more information in a single plot we include both the response times and the packet loss in a single plot and use a logarithmic y axis. Examples of such plots are shown below.

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Owner: Les Cottrell