TTCP(1) 						      General Commands Manual							   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 offset] [-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 rang-
       ing from tens of bytes to several ``pages'' can illuminate bottlenecks.

       Ttcp can also be used as a ``network pipe'' for moving directory hierarchies 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 receiving, 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 daemon.

       -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)

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