Passport 8000 Online Help 310b1

Implementation of rate limiting in the Passport 8000 Series switch

In the Passport 8000 Series switch, QoS rate metering is accomplished in increments of 64 bytes every 2.5 milliseconds. Table 156, Table 157, and Table 158 present the measured line rates, in multiples of 64, for the three Ethernet speeds tested, with the expected results. The rates were obtained using a source/destination filter.

The three tables illustrate the effective throughput in megabits per second (Mb/s) for various traffic flows using different rate-limiting values. All traffic loads are at 100% of interface speed, using fixed-sized packets of the size indicated (in bytes). Using these tables, you can determine the appropriate Average Rate Value that will give you the metering rate you want.

The Target Average Rate for each interface type is shown, in increments of 10% of total interface speed, to help you determine the appropriate Average Rate Value to use for that interface. The actual throughput rate typically differs slightly from the target rate as illustrated.

For example, to configure a traffic profile with an average rate limit of 50% of a 100 Mb/s interface (or 50 Mb/s), enter 250 in the AverageRate field in Device Manager. Traffic is then limited to 51.23 Mb/s to 53.47 Mb/s, depending on the size of the packets.

• Networking Concepts for the Passport 8000 Series Switch Release 3.1 for more information about rate metering