Reference Documentation

IntelĀ® PAC
Napatech SmartNIC
Reference Information
Napatech Software Suite: replay


The replay tool replays a data file created by the capture tool. The packets are transmitted according to the TxPort field in the packet descriptors of the packets. The TxPort field in the packet descriptors of the packets in the file is relative to port zero on the adapter used for replaying, and it is therefore required to specify an offset to port zero via the -p option. The replay rate is identical to the rate at which the packets were received (captured).


replay -f <file> -p <port offset> [--nocache] [-g <timestamp>] [-d <delay>] [-m <modfac>] [-s <starttime>] [-t] [--help]

Command Description
--help, -h Displays the help
--nocache By default, the replay tool caches data before replaying begins in order to support replaying at line-rate and not be limited by the hard drive. When specifying the --nocache parameter, the tool does not cache the data but reads it directly from the file.
-f <file> Specifies the file to replay. This file contains the data to be replayed.
-p <port offset> Port offset to port zero on the adapter on which the data should be replayed. The tool will replay data as received. However, the port offset from port 0 on the adapter on which data should be replayed must be provided.
-i <port number> Port on which a pcap file should be replayed (pcap and 4GA only, excludes -p option)
-g <timestamp>
--globalsync <timestamp>
Enable global synchronization mode.
The first 10 ns ticks time stamp to synchronize with.
-d <delay>
--delay <delay>
Transmission delay in milliseconds (default delay is zero)
-m <modfac>
--modfac <modfac>
Transmission begin time stamp modulus factor in seconds (default factor is 15 secs.)
-s <starttime>
--starttime <starttime>
Absolute transmission begin time stamp.
Find and print the first time stamp (in 10 ns ticks) in the capture file.
In order to replay to several ports exactly as captured, the adapter tx timing must be set to absolute in the ini-file and the globalsync option -g must be used with the value -g 0.


  • Replay on an NT4 adapter #2 in a system where 2 NT4 adapters exist.
    replay -f file.cap -p 4
  • Replay on an NT4 adapter #1.
    replay -f file.cap -p 0