The vcstat Command

This command has been included as it is familiar to users of SunNet X.25 7.0. In general, use x25stat, see "Checking the Datalink Layer".

The vcstat command allows you to monitor link and virtual circuit statistics, on a cumulative or periodic basis. The command has the following syntax

% /opt/SUNWconn/bin/vcstat [-L] [-n] [-l interface] [-i interval ] [-p period] 

The vcstat options are explained as follows:

-L

Display link-related statistics instead of virtual circuit statistics. By default, vcstat displays virtual circuit statistics. Examples of displays for each type of statistics are shown below.

-n

Display only cumulative (since reboot) statistics, instead of periodically updated display. By default, vcstat displays current statistics at 30-second intervals.

-l interface

Display statistics for the link specified by interface. This interface corresponds to the number specified for the interface parameter in your link configuration file.

-i interval

Sampling interval for display of cumulative statistics. If you omit this and the -n options, vcstat displays cumulative statistics at 30-second intervals.

-p period

Specifies the length of time, in minutes, vcstat will run when it is displaying current statistics. By default, vcstat displays statistics for 1440 minutes (24 hours).

-v virtual circuit

Specify a virtual circuit or range of virtual circuits.

-S symbolic address

Specify a symbolic address.

Virtual Circuit Statistics

Without the -L option (that is, by default), vcstat displays statistics for all currently active virtual circuits, rather than for links. For example:

hostname% /opt/SUNWconn/bin/vcstat -i10
Tue Sep 18 16:24:23 1990
   If LCN    State Substate Sent Recv Remote address MAC address
O 1 0x200 Data 0/0/0/0 130 130 129.144.133.2
O 1 0x201 Data 0/0/0/0 679 5180 10002244
I 2 0x202 Data 0/0/0/0 501 641 20009988       08:00:20:07:11:a1,0e 

The fields and headings in the above example display are explained as follows:

Column 1 (no heading)

In the first column you see either O, for an outgoing call; I, for an incoming call; or P, for a permanent virtual circuit.

If

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

State

Displays Data when the call is in the data transfer phase of the connection.

Substate

Displays four toggles (1 is true, 0 false). From left to right these are:

• Sent Receive Not Ready

• Sent Interrupt

• Received Interrupt

• Received Receive Not Ready

Sent and Recv

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

Remote Address

This field displays the following types of addresses:

• IP addresses for virtual circuits used for IP connections

• AEFs. This type of address is accompanied by a string, osi, partial-osi, or non-osi, indicating the type of AEF.

• X.121 addresses

To display a name or partial name from the xhosts table, use the --s option.

MAC Address

An LSAP address is present for virtual circuits running over LLC2.

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.

---

Note -

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

---

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.