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TTCP(1)			    General Commands Manual		       TTCP(1)

       ttcp - test TCP and UDP performance

       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]

       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 ma-
       chine, 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

       -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 de-
		 fault	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-

       -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

       -v	 Verbose: print	more statistics.

       -d	 Debug:	set the	SO_DEBUG socket	option.

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

				     local			       TTCP(1)


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