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I am tring to Specify tcpreplay speed but I can't do it this is my detail of test:

$tcpreplay -V tcpreplay version: 3.4.4 (build 2450)

1)$ tcpreplay -i %0 -p 100 -L 500 _udp_only.pcap Actual: 500 packets (42247 bytes) sent in 5.05 seconds.Rated: 8365.7 bps, 0.06 Mbps, 99.01 pps s

2)$ tcpreplay -i %0 -p 1000 -L 5000 _udp_only.pcap Actual: 5000 packets (427710 bytes) sent in 5.19 seconds. Rated: 82410.4 bps, 0.63 Mbps, 963.39 pps

//here is problem I stay in 966.00 pps

3)$ tcpreplay -i %0 -p 10000 -L 50000 _udp_only.pcap Actual: 50000 packets (4322559 bytes) sent in 51.76 seconds.Rated: 83511.6 bps, 0.64 Mbps, 966.00 pps

I have same problem when I try to Specify --mbps for 8600 packets 86 byte avg for each packet

-M0.086 -L 860 ----> Rated: 10812.9 bps, 0.08 Mbps, 127.22 pps

-M0.86 -L 860 ----> Rated: 83062.5 bps, 0.63 Mbps, 977.27 pps

-M0.86 -L 8600 ----> Rated: 82554.9 bps, 0.63 Mbps, 965.21 pps

why and how I can to Specify speed?

I use OS windows7

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Can you verify that some resource on your system isn't being saturated such as you processor or network interface? –  Jeff Ferland Jun 4 '12 at 14:09
    
my computer in rest and I try it from some other machine I think problem is parameters. –  herzl shemuelian Jun 4 '12 at 14:12

1 Answer 1

up vote 2 down vote accepted

A few comments:

  1. Windows support in tcpreplay is pretty much of a beta quality. High precision timing turns out to be very OS and hardware specific and Windows has the least amount of testing & development. You'll have better luck under Linux or OS X.

  2. Small packets + using the --mbps option (-M) is pretty much a worst case scenario for accurate packet timing. Using -M requires tcpreplay to dynamically calculate delays (more CPU intensive) and small packets makes even small inaccuracies in sending the packets look a lot worse when compared to larger packets.

  3. Your run of "-M0.086 -L 860 ----> Rated: 10812.9 bps, 0.08 Mbps, 127.22 pps" is pretty damn close. Tcpreplay only prints out two significant figures, so 0.08 for 0.086 is as "close" as you can expect.

share|improve this answer
    
+1, but wouldn't .086 round to .09 instead of .08? Also keep in mind that depending on the actual packets being replayed, they may not round evenly into the time frame/speed you are attempting to achieve. –  Jed Daniels Jun 5 '12 at 4:02
    
@Aron but when I try use pps Specify have also problem -L10000 -P2000 --> 1000.00 pps I can't pass 1000 pps –  herzl shemuelian Jun 5 '12 at 7:19

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