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     syncloop - synchronous serial loopback test program

     /usr/sbin/syncloop [-cdlstv] device

     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,  syn-
     cloop  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 particu-
     lar 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 pack-
     ets sent during this phase is determined by default  values,
     or by command line options. Each returned packet is compared
     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

     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

     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.

     The options for syncloop  are  described  in  the  following

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

     -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 confi-
                                          guration.   4:   Test   using
                                          predefined  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, syncloop prompts for it.

     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

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

     See attributes(5) for descriptions of the  following  attri-

    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Availability                | SUNWcsu                     |

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

     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

     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 pack-
         ets  sent  by  syncloop  and  the  number of packets the
         driver counted as transmitted,  or  between  the  number
         counted as received and the number read by the program.

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

Man pages from Solaris 10 Update 8. See docs.sun.com and www.oracle.com for further documentation and Solaris information.