Os campos são
registro de data e hora, endereço de origem, endereço de origem, endereço de destino, porto de destino, intervalo, bytes transferidos, bits_per_segundo
Deduzi isso olhando para
$ iperf -c localhost -r
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 648 KByte (default)
------------------------------------------------------------
[ 5] local 127.0.0.1 port 54401 connected with 127.0.0.1 port 5001
[ 4] local 127.0.0.1 port 5001 connected with 127.0.0.1 port 54401
[ ID] Interval Transfer Bandwidth
[ 5] 0.0-10.0 sec 50.3 GBytes 43.2 Gbits/sec
[ 4] 0.0-10.0 sec 50.3 GBytes 43.2 Gbits/sec
$ iperf -c localhost -r -y C
20140114124826,127.0.0.1,54402,127.0.0.1,5001,5,0.0-10.0,52551090176,42041052917
20140114124826,127.0.0.1,5001,127.0.0.1,54402,4,0.0-10.0,52551090200,41999020136
EDIT: Você pode encontrar o código fonte relevante aqui :
// TCP Reporting
printf( reportCSV_bw_format,
timestamp,
(stats->reserved_delay == NULL ? ",,," : stats->reserved_delay),
stats->transferID,
stats->startTime,
stats->endTime,
stats->TotalLen,
speed);
} else {
// UDP Reporting
printf( reportCSV_bw_jitter_loss_format,
timestamp,
(stats->reserved_delay == NULL ? ",,," : stats->reserved_delay),
stats->transferID,
stats->startTime,
stats->endTime,
stats->TotalLen,
speed,
stats->jitter*1000.0,
stats->cntError,
stats->cntDatagrams,
(100.0 * stats->cntError) / stats->cntDatagrams, stats->cntOutofOrder );
}