syncloop(1M)						  System Administration Commands					      syncloop(1M)

NAME

       syncloop - synchronous serial loopback test program

SYNOPSIS

       /usr/sbin/syncloop [-cdlstv] device

DESCRIPTION

       The syncloop command performs several loopback tests that are useful in exercising the various components of a serial communications link.

       Before  running a test, syncloop opens the designated port and configures it according to command line options and the specified test type.
       It announces the names of the devices being used to control the hardware channel, the channel number  (ppa)  corresponding  to  the  device
       argument, and the parameters  it has set for that channel. It then runs the loopback test in three phases.

       The first phase is to listen on the port for any activity.  If no activity is seen for at least four seconds, syncloop proceeds to the next
       phase. Otherwise, the user is informed that the line is active and that the test cannot proceed, and the program exits.

       In the second phase, called the "first-packet" phase, syncloop attempts to send and receive one packet. The program will  wait  for  up	to
       four  seconds  for the returned packet. If no packets are seen after five attempts, the test fails with an excoriating message. If a packet
       is returned, the result is compared with the original. If the length and content do not match exactly, the test fails.

       The final phase, known as the "multiple-packet" phase, attempts to send many packets through the loop. Because the program has verified the
       integrity  of  the  link  in  the first-packet phase, the test will not fail after a particular number of timeouts. If a packet is not seen
       after four seconds, a message is displayed. Otherwise, a count of the number of packets received is updated on the display once per second.
       If  it becomes obvious that the test is not receiving packets during this phase, the user may wish to stop the program manually. The number
       and size of the packets sent during this phase is determined by default values, or by command line options. Each returned  packet  is  com-
       pared  with its original for length and content. If a mismatch is detected, the test fails.  The test completes when the required number of
       packets have been sent, regardless of errors.

       After the multiple-packet phase has completed, the program displays a summary of the hardware event statistics for  the	channel  that  was
       tested. The display takes the following form:

	 CRC errors   Aborts   Overruns   Underruns   In<-Drops-> Out
		 0	   0	      0 	  0   0 	    0

       This  is  followed by an estimated line speed, which is an approximation of the bit rate of the line, based on the number of bytes sent and
       the actual time that it took to send them.

OPTIONS

       The options for syncloop are described in the following table:

       Option	   Parameter	 Default	     Description
       -c	 packet_count	 100	    Specifies the number of pack-
					    ets  to be sent in the multi-
					    ple-packet phase.
       -d	 hex_data_byte	 random     Specifies  that  each  packet
					    will  be  filled  with  bytes
					    with     the     value     of
					    hex_data_byte.

       -l	 packet_length	 100	    Specifies  the length of each
					    packet in bytes.
       -s	 line_speed	 9600	    Bit rate in bits per second.
       -v				    Sets verbose mode.	 If  data
					    errors  occur,  the  expected
					    and  received  data  is  dis-
					    played.
       -t	 test_type	 none	    A  number,	from 1 to 4, that
					    specifies which test to  per-
					    form.     The    values   for
					    test_type are as follows:  1:
					    Internal loopback test.  Port
					    loopback is on.  Transmit and
					    receive   clock  sources  are
					    internal (baud  rate  genera-
					    tor).  2:  External  loopback
					    test.  Port loopback is  off.
					    Transmit  and  receive  clock
					    sources	are	internal.
					    Requires   a   loopback  plug
					    suitable to  the  port  under
					    test.  3:  External  loopback
					    test.  Port loopback is  off.
					    Transmit  and  receive  clock
					    sources are external (modem).
					    Requires   that  one  of  the
					    local   modem,   the   remote
					    modem,  or	the remote system
					    be set in a loopback configu-
					    ration.  4: Test using prede-
					    fined    parameters.     User
					    defines  hardware  configura-
					    tion  and  may  select   port
					    parameters	    using     the
					    syncinit(1M) command.

       All numeric options except -d are entered as decimal numbers (for example, -s 19200). If you do not provide the -t test_type  option,  syn-
       cloop prompts for it.

EXAMPLES

       Example 1 A sample display of using the syncloop command.

       In the following command syncloop uses a packet length of 512 bytes over the first CPU port:

	 example# syncloop -l 512 zsh0

       In response to the above command, syncloop prompts you for the test option you want.

       The following command performs an internal loopback test on the first CPU port, using 5000 packets and a bit rate of 56Kbps:

	 example# syncloop -t 1 -s 56000 -c 5000 zsh0

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       syncinit(1M), syncstat(1M), attributes(5), zsh(7D)

DIAGNOSTICS

       device missing minor device number

	   The name device does not end in a decimal number that can be used as a minor device number.

       invalid packet length: nnn

	   The packet length was specified to be less than zero or greater than 4096.

       poll: nothing to read

       poll: nothing to read or write.

	   The poll(2) system call indicates that there is no input pending and/or that output would be blocked if attempted.

       len xxx should be yyy

	   The packet that was sent had a length of yyy, but was received with a length of xxx.

       nnn packets lost in outbound queueing

       nnn packets lost in inbound queueing

	   A  discrepancy  has been found between the number of packets sent by syncloop and the number of packets the driver counted as transmit-
	   ted, or between the number counted as received and the number read by the program.

WARNINGS

       To allow its tests to run properly, as well as prevent disturbance of normal operations, syncloop should only be run on a port that is  not
       being used for any other purpose at that time.

SunOS 5.11							    9 Mar 1993							      syncloop(1M)