Link Statistics

With the -L option, vcstat displays link-related, rather than virtual-circuit-related, statistics. It displays statistics for all currently active links. For example, to see link-related statistics, updated every 10 seconds, you enter:

hostname% /opt/SUNWconn/bin/vcstat -L -i10
 Wed Sep 19 08:56:52 1990
 If Type State SABM   Recv   Sent   Abort Crc Over Under
  0 hdlc UP     3      1112   1141   8     20   13 21
  1 hdlc UP     3      239    268    17    45   4   4
  2 llc UP      1      601    589    4     12   0   0

The fields in the vcstat output are explained as follows:

If

Identifies the link number over which the call was made. Corresponds to the value of the Link Number parameter in Link Editor window in x25tool.

Type

Can be lapb or llc, identifying the type of connection. The designator lapb indicates a serial-link connection, while llc indicates an LLC2 connection over a LAN.

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Note -

For LLC2, vcstat collects statistics on a per-physical-link basis, not per dynamic LLC2 link.

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State

Displays UP when the call is in the data transfer phase of the connection and DOWN when the call is being set up or taken down. Further, displays DOWN-SABM when the link is down and a SABM has been sent; DOWN-FRMR, when a link is down and a Frame Reject has been sent; and DOWN-DISC, when a link is down and a Disconnect has been sent.

SABM

Indicates the number of Set Asynchronous Balanced Mode frames that have been sent. This type of frame is used to establish a frame-layer connection.

Recv and Sent

Displays the number of frames sent and received since the last reboot. (These counts are not reset if you stop and restart your link.)

Abort

Displays the number of aborted received frames. Occurs when the local serial port received a sequence of eight consecutive ones, in violation of LAPB framing rules. Abort errors result from an interruption in the service provided by the link or from clocking problems. Such errors might also be caused by the software running over Solstice X.25. A small number of abort errors probably indicates a software problem rather than a broken link or a persistent clocking problem.

Crc

Reports the number of received frames with CRC (Cyclical Redundancy Check, an error detection method) errors. A CRC error is recorded when the checksum on a received frame is incorrect. CRC errors occur when there is a clocking problem (different rates on each side) or a noisy line.

Over

Reports the number of receiver overrun errors. Such errors occur when the local system is unable to accept data fast enough and the port hardware buffers overflow. A frame that is not completely received is aborted, triggering error recovery. Underrun errors can occur when the signaling rate in use on a link is too fast for the local system.

Under

Reports the number of transmitter underrun errors. Such errors occur when the local system is too busy to service the serial port hardware. A frame that is not completely sent is aborted, triggering error recovery. Underrun errors can occur when the signaling rate in use on a link is too fast for the local system.