NAME

nmreplay — playback a pcap file through a netmap interface

SYNOPSIS

nmreplay

[-f pcap-file] [-i netmap-interface] [-B bandwidth] [-D delay] [-L loss] [-b batch size] [-w wait-link] [-v] [-C cpu-placement]

DESCRIPTION

nmreplay works like tcpreplay to replay a pcap file through a netmap interface, with programmable rates and possibly delays, losses and packet alterations. nmreplay is designed to run at high speed, so the transmit schedule is computed ahead of time, and the thread in charge of transmission only has to pump data through the interface. nmreplay can connect to any type of netmap port.

Command line options are as follows

-f pcap-file

Name of the pcap file to replay.

-i interface

Name of the netmap interface to use as output. See netmap(4) for interface name format.

-v

Enable verbose mode

-b batch-size

Maximum batch size to use during transmissions. nmreplay normally transmits packets one at a time, but it may use larger batches, up to the value specified with this option, when running at high rates.

-B bps | constant,bps | ether,bps | real[,speedup]

Bandwidth to be used for transmission. bps is a floating point number optionally follow by a character (k, K, m, M, g, G) that multiplies the value by 10^3, 10^6 and 10^9 respectively. constant (can be omitted) means that the bandwidth will be computed with reference to the actual packet size (excluding CRC and framing). ether indicates that the ethernet framing (160 bits) and CRC (32 bits) will be included in the computation of the packet size. real means transmission will occur according to the timestamps recorded in the trace. The optional speedup multiplier (defaults to 1) indicates how much faster or slower than real time the trace should be replayed.

-D dt | constant,dt | uniform,dmin,dmax | exp, dmin,davg

Adds additional delay to the packet transmission, whose distribution can be constant, uniform or exponential. dt, dmin, dmax, avt are times expressed as floating point numbers optionally followed by a character (s, m, u, n) to indicate seconds, milliseconds, microseconds, nanoseconds. The delay is added to the transmit time and adjusted so that there is never packet reordering.

-L x | plr,x | ber,x

Simulates packet or bit errors, causing offending packets to be dropped. x is a floating point number indicating the packet or bit error rate.

-w wait-link

indicates the number of seconds to wait before transmitting. It defaults to 2, and may be useful when talking to physical ports to let link negotiation complete before starting transmission.

OPERATION

nmreplay creates an in-memory schedule with all packets to be transmitted, and then launches a separate thread to take care of transmissions while the main thread reports statistics every second.

SEE ALSO

netmap(4)

AUTHORS

nmreplay has been written by Luigi Rizzo, Andrea Beconcini, Francesco Mola and Lorenzo Biagini at the Universita` di Pisa, Italy.