Why is tcpreplay not sending all the packets?
Every now and then, someone emails the tcpreplay-users list, asking if there is a bug in tcpreplay which causes it not to send all the packets. This usually happens when the user uses the -t flag or is replaying a high-speed pcap file (> 50Mbps, although this number is dependant on the hardware in use). The short version of the answer is: no, we are not aware of any bugs which might cause a few packets to not be sent. The longer version goes something like this: If you are running tcpreplay multiple times and are using tcpdump or other packet sniffer to count the number packets sent and are getting different numbers, it’s not tcpreplay’s fault. The problem lies in one of two places: • It is well known that tcpdump and other sniffers have a problem keeping up with high-speed traffic. Furthermore, the OS in many cases lies about how many packets were dropped. Tcpdump will repeat this lie to you. In other words, tcpdump isn’t seeing all the packets. Usually this is a problem with the netw
