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HP ProCurve Switch 4000M / 8000M / 2424M / 1600M Reviewer’s Guide

3. Performance Testing

Switches are normally performance tested under a variety of conditions for three main parameters:

throughput/packet loss rate, congestion control and latency. Definitions for throughput, packet loss

rate and latency are specified in RFC 1242. See

http://www.rfc-editor.org/

. Unfortunately, there is no

clear definition for congestion control. There are numerous tests that test different aspects of

congestion control, none of which is considered the definitive test for congestion.

Keep in mind that most of these tests are performed in an artificial environment intended to measure

the outer limits of switches and rarely, if ever, reflect circumstances a switch would consistently find in

an actual network environment. This is particularly true for congestion type testing. The applicability of

these performance numbers to real world networks has to be interpreted carefully, as most switches in

these tests perform to a level significantly exceeding the needs of real world networks.

Additional comments on each of the parameters follows.

3.1 Throughput/Packet Loss Rate

Hardware is now available to the switch designer to allow designs that can handle media-speed streams

on all ports simultaneously. This does, in most cases, come at an increased price for the switch to

customers. As a result, designs for switches are a tradeoff of total throughput versus cost. This tradeoff

is most apparent for high port density switches, where the cost of providing media-speed throughput

on all ports simultaneously can be high, while the actual need for this level of throughput is doubtful.

3.1.1 HP ProCurve Switch 4000M / 8000M

This tradeoff can be seen in Appendix A in the throughput numbers for the HP ProCurve Switch 4000M

or 8000M, both high port density switches. With 40 port pairs active (i.e. all 80 ports connected and

passing half duplex traffic), the Switch 4000M or 8000M reported a 94.1% traffic throughput with 1518

byte packets and 78.5% with 64 byte packets. Forty full-duplex port pairs active at 100Mbps is the

equivalent of sending 4 Gbps through the switch. With the Switch 4000M and 8000M backplanes rated

at 3.8 Gbps (based on backplane clock speed) there are some packet drops to be expected at this traffic

level and this is seen with 1024 byte packets and larger. Backplane throughput, calculated from these

figures, is shown to be approximately 3.73 Gbps for actual throughput. The increase in drops (as shown

by the lower percentage) below the 1024 byte packet length is due to the switch engine overhead of

having to make many more forwarding decisions (as shown in the total packets column). This is

particularly evident in the 64 byte packet test.

This test shows the maximum packet per second rate for the HP ProCurve Switch 4000M and 8000M is

4.67 million 64 byte packets. This performance is excellent, particularly given the HP ProCurve

Switch 4000M and 8000M’s low cost.

3.1.2 HP ProCurve Switch 2424M

The HP ProCurve Switch 2424M has a backplane rated at 3.2 Gbps. When maximum full duplex traffic

is sent through the 24 fixed 10/100 ports and 2 Gigabit ports on an installed Stacking Module, the data

rate is theoretically 4.4 Gbps, so packet drops at this traffic level are expected. As seen in Appendix A,

the HP ProCurve Switch 2424M with 512 byte packets and above show a throughput rate of about

72.5%. This is equivalent to a backplane speed of 3.19 Gbps, which lines up nicely with the actual

backplane speed. With packets smaller than 512 bytes the throughput rate is affected the ability of the

switch to handle the higher number of packets seen with smaller packet sizes. The maximum packet

handling rate is with 64 byte packets where the HP ProCurve Switch 2424M handled 3.92 million

packets per second. This packet handling ability is more than sufficient for the typical desktop switch

environment and better than the other major vendors’ stackable solutions. Compare these numbers to

those posted in a test conducted by the Tolly Group on several stackable switches. The report,

No. 8286, is available at

http://www.tolly.com/

under Custom Tests in the Test Results area of the site.