How do you calculate the max achievable throughput of a platform?

[nedk12345]

Hi I am trying to find out how would one go about calculating the maximum achievable throughput on a platform based on the PPS numbers that are in the various performance docs. I have searched through the forum and am unable to find a post that I had found a while back which listed all the calculation details and the detailed description on how the numbers are achieved. Can someone share this valuable information as I know it was discussed before or point me to link that explains all the math and theory.

For eg. How can one tell what the max achievable performance would be on a 3845 or a 7200 w/ NPE-G2?

Is there a calculation to figure out if these devices can do line rate 1Gb or not and what is that math?

If it cannot do 1Gb what can it do on varied packet size in network like mixture of 1500 and 64 byte packet size

Is there a way to verify the forwarding performance that cisco posts on its performance sheets based on theoritical calculations and what is those calcs?

Is calculation performed on Packets Per Sec or Mbps or both?

If enabling features is there a way to determine how much impact it will have on the performance so if NAT is enabled or QOS etc

Thx

[Robert Taylor]

The numbers given are determined by many different things.

The PPS (best case) is determined through a test at different packet sizes.  Thus, some packet sizes would have a different max PPS than other packet sizes.  iPerf is a useful tool for doing actual measurements yourself, based on whatever features you need on the router itself.  However, since its an actual real traffic generation tool, you must already have purchased the device in order to get realistic results for your specific scenario.

Features such as nat/ipsec/qos ALL have an impact on the throughput performance, which is why its hard to rely on these specs for your own deployment, but rather it is more useful for comparing between platforms.

Sales teams and partners would probably have more details for this type of data, but, in general, YMMV depending on your specific feature combinations and configurations.