ttcp



TTCP(1)                                                                TTCP(1)




NAME

       ttcp - test TCP and UDP performance


SYNOPSIS

       ttcp   -t   [-u]  [-s]  [-p port]  [-l buflen]  [-b size]  [-n numbufs]
       [-A align] [-O offset] [-f format] [-D] [-v] host [<in]
       ttcp -r [-u] [-s] [-p port] [-l buflen] [-b size]  [-A align]  [-O off-
       set] [-f format] [-B] [-T] [-v] [>out]


DESCRIPTION

       Ttcp  times  the transmission and reception of data between two systems
       using the UDP or TCP  protocols.   It  differs  from  common  ‘‘blast’’
       tests,  which  tend  to measure the remote inetd as much as the network
       performance, and which usually do not allow measurements at the  remote
       end of a UDP transmission.

       For testing, the transmitter should be started with -t and -s after the
       receiver has been started with -r and -s.  Tests lasting at least  tens
       of  seconds  should be used to obtain accurate measurements.  Graphical
       presentations of throughput versus buffer size for buffers ranging from
       tens of bytes to several ‘‘pages’’ can illuminate bottlenecks.

       Ttcp  can also be used as a ‘‘network pipe’’ for moving directory hier-
       archies between systems when routing problems exist or when the use  of
       other  mechanisms  is  undesirable.  For  example,  on  the destination
       machine, use: ttcp -r -B | tar xvpf -

       and on the source machine: tar cf - directory | ttcp -t dest_machine

       Additional intermediate machines can be included by: ttcp -r | ttcp  -t
       next_machine


OPTIONS

       -t        Transmit mode.

       -r        Receive mode.

       -u        Use UDP instead of TCP.

       -s        If transmitting, source a data pattern to network; if receiv-
                 ing, sink (discard) the data.  Without  the  -s  option,  the
                 default  is to transmit data from stdin or print the received
                 data to stdout.

       -l length Length of buffers in bytes (default  8192).   For  UDP,  this
                 value is the number of data bytes in each packet.  The system
                 limits the maximum UDP  packet  length.  This  limit  can  be
                 changed with the -b option.

       -b size   Set size of socket buffer.  The default varies from system to
                 system.   This  parameter  affects  the  maximum  UDP  packet
                 length.  It may not be possible to set this parameter on some
                 systems (for example, 4.2BSD).

       -n numbufs
                 Number of source buffers transmitted (default 2048).

       -p port   Port number to send to or listen on (default 2000).  On  some
                 systems,  this  port may be allocated to another network dae-
                 mon.

       -D        If transmitting using TCP, do not buffer  data  when  sending
                 (sets the TCP_NODELAY socket option).  It may not be possible
                 to set this parameter on some systems (for example,  4.2BSD).

       -B        When receiving data, output only full blocks, using the block
                 size specified by -l.  This option is  useful  for  programs,
                 such as tar(1), that require complete blocks.

       -A align  Align the start of buffers to this modulus (default 16384).

       -O offset Align  the  start of buffers to this offset (default 0).  For
                 example, ‘‘-A8192 -O1’’ causes buffers to start at the second
                 byte of an 8192-byte page.

       -f format Specify, using one of the following characters, the format of
                 the throughput rates  as  kilobits/sec  (’k’),  kilobytes/sec
                 (’K’),  megabits/sec (’m’), megabytes/sec (’M’), gigabits/sec
                 (’g’), or gigabytes/sec (’G’).  The default is ’K’.

       -T        ‘‘Touch’’ the data as they are read in order to measure cache
                 effects.

       -v        Verbose: print more statistics.

       -d        Debug: set the SO_DEBUG socket option.


SEE ALSO

       ping(1M), traceroute(1M), netsnoop(1M)



                                     local                             TTCP(1)

Man(1) output converted with man2html