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NS 3000/iX LAN Link Statistics

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The following section describes the data that is output when you issue the LINKCONTROL command to obtain statistics relating to NS 3000/iX LAN Links.

LINKSTATE Parameter Fields

The following is an example of the data that is displayed when you issue the LINKCONTROL linkname;STATUS=LINKSTATE command: 

 Linkname:  SYSLINK   Linktype:  IEEE802.3   Linkstate:  CONNECTED
Linkname — The Linkname field specifies the name of the link.

Linktype — The Linktype field specifies the type of link, such as LAP-B or IEEE 802.3, that is being monitored.

Linkstate — The Linkstate field specifies the current state of the link. The possible link states are as follows:

  • Connected

  • Not connected

NOTE: Some of the parameter descriptions that follow vary according to whether your LAN card is a CIO card or an NIO card.

CONFIGURATION Parameter Fields

The CONFIGURATION parameter for IEEE 802.3 links displays several fields in addition to the LINKSTATE parameter field. The following is an example of the data that is displayed when you issue the LINKCONTROL linkname;STATUS=CONFIGURATION command: 
Physical Path:                  4.6
Inbound Buffer Size:            1536 (CIO only)
Inbound Number of Buffers:      64 (CIO only)
Inbound Buffers Available:      41 (CIO only)
Current Station Address:        08-00-09-02-3D-9B
Default Station Address:        08-00-09-02-3D-9B
Current Receive Filter:         bad(0) multi(1) broad(1) any(0)
Current Multicast Addresses:    09-00-09-00-00-01
Physical Path — The Physical Path field displays the current physical path for the LAN card as specified in the NMMGR configuration file.

Inbound Buffer Size — The Inbound Buffer Size field displays the current size of the receive buffer that are configured for this system through NMMGR. This field will not print for NIO cards, since there may be multiple inbound buffer sizes.

Inbound Number of Buffers — The Inbound Number of Buffers field displays the number of receive buffers that are configured for this system through NMMGR. This field will not print for NIO cards.

Inbound Buffers Available — The Inbound Buffers Available field displays the number of unused or unassigned Inbound Buffers that are available to this system. This field will not print for NIO cards.

Current Station Address — The Current Station Address field is a display of the six (6) byte address to which the node is configured to respond. This address is used whenever frames are sent to the network media. The default station address is used unless it is overridden in the NMMGR link configuration screen. If this field is changed, then the station address of this node is changed. Make sure that you note this new address in the system manager log.

Default Station Address — The Default Station Address field is the default value for the Current Station Address described above. The default station address is determined by the specific LAN card. It is also printed on the LAN card. If the card is changed for any reason, the Default Station Address of this node will change.

Current Receive Filter — The Current Receive Filter field has a current value. The current value is currently used by the LAN card.

Receive Filter bad ( ) — The Receive Filter bad ( ) field is either enabled (1) or disabled (0). When enabled, any bad frames that are received by the LAN are passed to the driver. When disabled, bad frames are discarded. Any bad frames are counted in the statistics.

Receive Filter multi ( ) — The Receive Filter multi ( ) field is either enabled (1) or disabled (0). When enabled, you can specify a list of specified multicast frames to be received by the LAN hardware card. The list can contain up to 64 multicast addresses to be downloaded to the LAN and is displayed when this field is entered.

Receive Filter broad ( ) — The Receive Filter broad ( ) field is either enabled (1) or disabled (0). When enabled, the LAN card receives frames sent to the broadcast address.

Receive Filter any ( ) — The Receive Filter any ( ) field is either enabled (1) or disabled (0). When enabled, the LAN card attempts to receive all frames from the network media. When disabled, only those frames sent to the LAN card are received.

Receive Filter k_pckts() (NIO card only) — The Receive Filter k_pckts() filed is either enabled (1) or disabled (0). When enabled, the LAN card keeps frames received from the network media, even if no buffers are currently posted to the card. If this option is not enabled, the frames will be dropped.

Receive Filter x_pckts() (NIO card only) — The Receive Filter x_pckts() field is either enabled (1) or disabled (0). When enabled, any XID or TEST commands sent to DSAP 0 will be responded to by the driver, and not the card.

Current Multicast Addresses — The Current Multicast Addresses field contains a list of all multicast addresses to which the LAN card responds. The default multicast address list contains no addresses. If no multicast addresses are specified, the following message is printed:

Current multicast address list is empty

Multicast addresses are configured through NMMGR. The maximum number of multicast addresses allowed is 16. The meanings of the following specific multicast addresses are as follows:
09-00-09-00-00-01

Probe address

09-00-09-00-00-02

Second probe address

09-00-09-00-00-03

LAN analysis (LANDAD)

09-00-09-00-00-04

DTC boot address

STATISTICS Parameter Fields

The STATISTICS parameter for IEEE 802.3 links displays many fields in addition to the LINKSTATE parameter fields. The CONFIGURATION parameter fields are not displayed when this parameter is used. The following is an example of the data that is displayed when you issue the LINKCONTROL linkname;STATUS=STATISTICS command: 
Transmits no error          1     Receives no error      343
Transmits error             0     Receives error           0
Out of TX bufs              0     Out of Rx bufs           0
Transmits deferred          0     Carrier losses           0
Transmits 1 retry           0     Reflectometer            0
Transmits >1 retry          0     CRC errors               0
Transmits 16 collisions     0     Whole byte errors        0
Transmits late collision    0     Size range errors        0
802 chip restarts           0     Frame losses             0
Heartbeat losses            0
This command displays statistics about data transmitted across the link. All field values, except for those under Receive Filter, are summations. Over time, the values in these fields reach their maximum possible value. When this occurs, these fields can only be reset manually.

Transmits no error — The Transmits no error field specifies the number of frames that were successfully transmitted onto the medium. This includes the number of frames that were successfully transmitted on the first attempt, as well as frames that were successfully transmitted after being deferred or that experienced one or more collisions. The maximum value of this 32-bit field is 4294967295.

Receives no error — This field specifies the number of frames that were successfully received over the medium. This includes the number of frames that were successfully received on the first attempt, as well as frames that were successfully received after being deferred or that experienced one or more collisions. The maximum value of this 32-bit field is 4294967295.

Transmits error — The Transmits error field specifies the number of transmission errors sent across the link. The value in this field specifies the number of frames which, due to errors on the link, were never transmitted. Although this value is commonly greater than 5% of the total number of frames transmitted, if it reaches or exceeds 5% of the total number of frames, check the hardware or check to see if the LAN is overloaded.

Receives error — The Receives error field specifies the number of transmission errors that were received from the link. The value in this field specifies the number of frames which were received, but were corrupted due to errors on the link. This value includes all frames which were discarded because of the setting of the current receive filter.

Out of Tx bufs (CIO card only) — The Out of Tx bufs field specifies the number of times that the LAN device adaptor (DA) reported to the driver that no transmit buffers were available. The maximum value of this 32-bit field is 4294967295.

Out of Rx bufs (CIO card only) — The Out of Rx bufs field indicates the number of times the LAN card reported to the driver that no receive buffers were available. This indicates only that the next buffer space was full and that the buffer pointer could not be incremented to an available buffer (the buffer pointer is incremented only after the driver requests the next frame). This also does not indicate that any frames were lost, however if another frame arrives before a receive buffer is made available, that frame will be lost. The value of this field should be very low. Retransmissions will occur if the link is out of Rx bufs. The maximum value for this 32-bit field is 4294967295.

Transmits deferred — The Transmits deferred field indicates the number of frames that deferred to other traffic before being transmitted onto the network. This means that the LAN card had to wait for carrier to drop, and stay dropped for 9.6 nanoseconds, before attempting to transmit the frame. This statistic only counts the number of frames that were deferred and later transmitted without collision.

Carrier losses — The Carrier losses field indicates that the transmitting node turned off the carrier signal on the cable. This occurred for one of the following reasons:

  • The stub cable is not connected to the frontplane connector.

  • The AUI (or AUI pigtail for ThinMAU) is not connected to the stub cable.

  • The MAU is broken.

  • If using thick LAN cable, there may be a short close to the MAU (ThinLAN cable shorts show up as a retry error as described in the Transmits 16 collision field description).

If the LAN continuously loses carrier, the problem is probably caused by a disconnected AUI or stub cable. Make sure that all connectors from the frontplane of the LAN hardware card to the MAU are connected securely.

NOTE: Collisions occur on IEEE 802.3 Local Area Network (LAN) links whenever two nodes on the link attempt to transmit data at the same time. When a collision occurs, the nodes which were involved in the collision each wait a random amount of time, called random backoff, before attempting to again transmit the packet along the link. If collisions continuously occur, check the terminators. Many of the fields described in this section are incremented whenever a collision occurs.

Transmits 1 retry — This field indicates the number of frames that collided once before being transmitted successfully. This means that the random backoff strategy was only used once.

Reflectometer (CIO card only) — The reflectometer field is similar in function to a TDR (Time Domain Reflectometer). The statistic holds the time count between the pulse and a reflection. Whenever a retry error occurs, the time in bit times (100ns) from when the frame started to transmit until the collision occurred is stored by this statistic. This can be useful for grossly determining the location of an opening in a cable, or possibly, a short in a ThinLAN cable. This field is erased after every transmit and is not updated after an external loopback frame is transmitted onto the link.

While this statistic may aid in pinpointing a problem without the need to do an actual TDR test, it should be noted that this statistic calculates the distance using a rough estimate (bit time) and can be inaccurate. This statistic should never be used as the only means of locating a cable fault. However, if this field is not equal to 0, then the hardware of the node is a likely cause of the failure.

The reflectometer field, for a thick LAN cable, is calculated in the following manner: 

  The ThickLAN velocity of propagation   =   .77c
  Where c (the speed of light)           =   3x10 E8
  The bandwidth of a LAN                 =   10Mb/sec.
Before determining the level of cable fault isolation, you must first determine how many meters of the cable are covered per bit time. You then divide .77c by 10Mb/sec. This translates into: 

      7x10E-2) x (3x10E8)
      __________________   = 231 meters
      10E6 b/sec)
Therefore, in order to pinpoint a fault in a thick LAN cable by the value of this field, multiply the field value by 231 meters.

The accuracy of the reflectometer field is plus or minus 1/2 bit time, or 115m. Using this calculation, the location of the cable fault is determined by the following formula:

(value of field x 231 meters) +\- 115m

Since the maximum length of a cable is 500m, the value of this field would be 0, 1 or 2, and would pinpoint a cable fault to 1 of 3 sections of cable.

If this value were to be used for isolating a cable fault in a ThinLAN cable, the value 0.65 would be substituted for .77c in the calculation above. (The ThinLAN velocity of propagation is .65c).

Transmits >1 retry — The Transmits >1 retry field indicates the number of frames that collided more than one, but fewer than 16 times, before being transmitted successfully onto the link. If the frame was not transmitted successfully (more than 16 attempts were made without success), then the card aborts transmission of this frame, and it counts the event as a retry error (see the Transmits 16 collision field).

CRC errors — The CRC errors field specifies the number of cyclic redundancy check (CRC) errors that were seen on the link. A CRC error indicates that the frame was checked using CRC-32 frame-checking, but that the value obtained by the CRC did not match the CRC value contained within the packet.

Normally there will be an equal number of alignment errors. If alignment errors occur frequently, one of the following may be the cause:

  • A LAN card is not listening to the link before transmitting.

  • A repeater that is performing poorly.

  • A section of LAN coax which contains an impedance.

  • The driver level of a MAU is set too low.

Transmits 16 collisions — The Transmits 16 collisions field indicates the number of times a frame or frames were not transmitted because 16 consecutive collisions occurred. This commonly occurs in the protocol during periods of high network utilization. If your node is experiencing continuous retry errors, the problem is most likely that a terminator has been removed from the cable. Other possible causes include the following:

  • There is an opening in the cable.

  • If ThinLAN cable is used, the AUI may be disconnected.

  • The LAN cable may shorted.

Whole byte errors — The Whole byte errors field is the number of frames received that were not an integer multiple number of bytes long. This occurs when an entire byte is not transmitted. This usually also causes the CRC error to be set.

Transmits late collision — This field indicates that a frame was active in the network for a longer time than is permitted by the protocol. The IEEE 802.3 protocol expects each frame to be transmitted within one slot time (the expected time for a 512 bit packet to traverse the entire network). The slot time exceeds the amount of time a single frame should need to traverse the entire network.

A value in this field indicates that a network problem caused a late collision. A late collision is one in which the collision occurs after one slot time has passed and another node, sensing that the network is inactive, begins to transmit a frame. Late collisions are caused by one of the following:

  • Broken LAN cards in the network.

  • A network that is too long.

A network can be made too long by installing too many repeaters between nodes. HP MAUs inform the LAN card of collisions after the 512 bit timer expires even though IEEE 802.3 standards do not require the MAU to monitor the link beyond that time. No attempt is made to retransmit a frame after a late collision.

Size range errors — The Size range errors field indicates the number of frames received that are not within the allowable size range. The allowable size range is 64-1518 bytes long. Unless the save bad frames bit is set on the LAN hardware card, the LAN hardware card throws these packets out.

802 chip restarts — The 802 chip restarts field was initially used to count the number of times that a specific version of the LAN chip locked up. This problem was remedied by a new version of that chip, however, this field still returns a value when one of the following events occurs:

  • An AUI cable that is shorted and sending an intermittent signal to any of the connectors.

  • Infinite deferral errors.

  • "Jabbering" MAU.

  • Noise from another node.

  • Bad chips.

The value of the 802 chip restarts field provides information about the performance of the LAN card and the status of the LANCE chip status for overflow/underflow errors (this is monitored by firmware).

Frame losses — The frame losses field indicates the number of times that the LAN controller chip indicated that it has lost a frame. After some delta period of time following a transmission, no collision detect is seen. This is typically because there are no free receive buffers when a frame arrives.

Receives Dropped (NIO card only) — The Receives Dropped field indicates the total number of frames that were dropped because there was no receive buffer posted.

Receives Broadcast (NIO card only) — The Receives Broadcast field indicates the total number of frames received that were addressed to a broadcast address. If no broadcasts have been received, check the current receive filter to ensure that broadcasts are enabled. If broadcasts are enabled and no broadcasts have been received, this may be an indication of a faulty LAN card.

Receives Multicast (NIO card only) — The Receives Multicast field indicates the total number of frames received that were addressed to a multicast address. If no multicast frames are being received, check to make sure that the desired multicast address(es) are listed as part of the current multicast addresses.

Heartbeat losses — The Heartbeat losses field indicates that no SQE heartbeat was seen after a transmission and when IEEE 802.3 stub cable was connected. After a successful transmission, the 802.3 MAU sends an SQE message, called a "heartbeat," through the Control In wire of the AUI. This heartbeat function lets the card know that the MAU is still functioning properly.

NOTE: This statistic is not to be set if the Ethernet stub cable is connected.



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