The following section describes the data that is output when you issue the
LINKCONTROL command to obtain statistics relating to NS 3000/iX
100Base-T 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 — The Likname field specifies the name of the link.
Linktype — The Linktype field
specifies the type of link, such as LAP-B, 100BT, or IEEE 802.3,
that is being monitored, and the type of I/O bus it is installed
on (will be preceded with "PCI" for PCI 100Base-T links).
Linkstate — The Linkstate
field specifies the current state of the link. The possible link
states are as follows:
Connected
Not connected
CONFIGURATION Parameter Fields
The CONFIGURATION parameter for 100Base-T links displays
several fields in addition to the LINKSTATE parameter field. This is
an example of the data that is displayed when you issue the
LINKCONTROL linkname;STATUS=CONFIGURATION command:
Physical Path: 10/4/8
Current Station Address: 08-00-09-DD-A2-5C
Default Station Address: 08-00-09-DD-A2-5C
Current Multicast Addresses:
99-00-09-00-00-01 09-00-09-00-00-03 09-00-09-00-00-04
09-00-09-00-00-06
Physical Path — The Physical
Path field displays the current physical path for the adapter card
as specified in the NMCONFIG configuration file.
NOTE: On PCI 100Base-T links, the physical path generally has more
components and is a "longer" path (e.g., 1/12/0/0). Otherwise, output for PCI
links is the same as HP-PB.
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 adapter card. On HP-PB systems, it is
also printed on a small label attached to a circuit board on the
adapter card.
NOTE: This printed label is not available for PCI adapter
cards. If the adapter card is changed for any reason, the Default
Station Address of this node will change.
Current Multicast Address List — The
Current Multicast Addresses field contains a list of all multicast
addresses to which the adapter card responds. The default multicast
address list contains no addresses. If no multicast addresses are
enabled, the follow message is printed:
Current multicast address list is empty
Multicast addresses are configured automatically by the network transport(s)
using the adapter card. For PCI 100BT links, the maximum number
of multicast addresses currently allowed is 14 (this is due to an
implementation decision regarding how the PCI 100BT card manages
multicast addresses). An example of multicast addresses are:
09-00-09-00-00-01
Probe address
09-00-09-00-00-02
Second probe address
09-00-09-00-00-04
DTC boot address
STATISTICS Parameter Fields
The STATISTICS parameter for 100Base-T links displays many
fields in addition to the LINKSTATE parameter fields. The
CONFIGURATION parameter fields are not displayed when this
parameter is used. For an example of the data that is displayed when you issue
the LINKCONTROL linkname;STATUS=STATISTICS command:
Transmit bytes 10191188 Receive bytes 495231926
Transmits 127700 Receives 113968
Transmits no error 127700 Receives broadcast 3955124
Transmits dropped 0 Receives multicast 1743137
Transmits deferred 1738 Receives no error 15688503
Transmits 1 retry 86 CRC or Maxsize error 0
Transmits >1 retry 179 Code or Align error 0
Trans 16 collisions 0 Recv dropped: addr 9876255
Trans late collision 0 Recv dropped: buffer 0
Trans underruns 0 Recv dropped: dma 0
Carrier losses 0 Recv dropped: other 19
Link disconnects 0 Recv deferred 0
Link speed 10 Recv overruns 0
Link duplex Half Link auto sensed No
Link mode 100Base-TX Secs since clear 2602760
The following example of the LINKCONTROL output for a PCI 100Base-T link
(some of the statistics differ for PCI).
Transmit bytes 10191188 Receive bytes 495231926
Transmits 127700 Receives unicast 113968
Transmits no error 127700 Receives broadcast 3955124
Transmits dropped 0 Receives multicast 1743137
Transmits deferred 1738 Receives no error 15688503
Transmits 1 retry 86 Recv CRC error 0
Transmits >1 retry 179 Recv maxsize error 0
Trans 16 collisions 0 Recv dropped: addr 9876255
Trans late collision 0 Recv dropped: buffer 0
Trans underruns 0 Recv dropped: descr 0
Carrier losses 0 Recv dropped: other 19
Trans jabber timeout 0 Recv watchdg timeout 0
Link disconnects 0 Recv collisions 0
Link speed 10 Recv overruns 0
Link duplex Half Link auto sensed No
Link mode 100Base-TX Addon Secs since clear 5259
NOTE: Some of the parameter descriptions vary according to whether the
adapter card is operating at 100Mbps or 10Mbps speed. Most also apply to an
HP-PB 100VG-AnyLAN card operating in 10Base-T mode.
This command displays statistics about data transmitted and
received across the link. Many field values are summations. Over
time, the values in these fields reach their maximum possible value.
When this occurs, these fields can only be reset manually.
Transmit bytes — Total number
of bytes successfully transmitted onto the medium. This includes
unicast, broadcast, and multicast 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 printable value of this 64-bit field is
17 digits, or about 99 million Gbytes. In the previous example,
10.1 million bytes were transmitted, or about 9.7 Mbytes.
Transmits — Total number of
frames successfully transmitted onto the medium at normal priority.
This includes unicast, broadcast, and multicast 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 byte count given by Transmit
bytes is distributed over this number of frames. The maximum printable
value of this 64-bit field is 17 digits, or about 99 million billion
frames. In the previous example, 127700 frames were transmitted
at normal priority.
Transmits no error — Total
number of frames the adapter card reports it successfully transmitted
onto the medium. These adapter card statistics are periodically
read, and are accumulated by the link driver. The total includes
all unicast, broadcast, and multicast 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. It should equal the value of "Transmits".
The maximum printable value of this 64-bit field is 17 digits, or
about 99 million billion frames. In the previous example, 127700
frames were transmitted.
Transmits dropped — Total
number of frames the link driver discarded because the transmit
queue was full, or because the data to be sent was fragmented beyond
recognition. The maximum value of this 32-bit field is 2147483647.
It would be unusual for this statistic to contain a nonzero value.
NOTE: Collisions occur on 100Base-T Local Area Network links
whenever two nodes on the link attempt to transmit data at the same
time. When a collision occurs, each node involved in the collision
waits a random amount of time, called random backoff, before attempting
to again transmit the frame along the link. Many of the fields described
in this section are incremented whenever a collision occurs.
Transmits deferred — Total
number of frames that were deferred to other network traffic before
their initial transmission onto the network. This means that the
100Base-T card had to wait for carrier to drop and stay dropped
for a few nanoseconds, before attempting to transmit the frame.
The maximum printable value of this 64-bit field is 17 digits, or about
99 million billion frames. In the previous example, 1738 transmit frames
were deferred.
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. The maximum printable value of this 64-bit field is 17
digits, or about 99 million billion frames. In the example above,
86 frames were transmitted after only one collision. This statistic
is not logged when the adapter card is operating in full duplex
mode, and would print as 0.
Transmits >1 retry — This
field indicates the number of frames that collided more than once,
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 in the "Trans 16
collisions" field. The maximum printable value of this 64-bit
field is 17 digits, or about 99 million billion frames. In the previous
example, 179 frames were transmitted after experiencing between
2 and 15 collisions. This statistic is not logged when the adapter
card is operating in full duplex mode, and would print as 0.
Trans 16 collisions — This
field indicates the number of times a frame was not transmitted,
because 16 consecutive collisions occurred. This can occur during
periods of high network utilization. If the node is experiencing
many Trans 16 errors, possible causes include the following:
The network is saturated with traffic.
There is a short in the cable.
There is an opening in the cable.
The maximum value of this 32-bit field is 2147483647. This
statistic is not logged when the adapter card is operating in full
duplex mode, and would print as 0.
Trans late collision — This
field indicates that a frame was active in the network for a longer
time than is permitted by the protocol. No attempt is made to retransmit
a frame after a late collision. The IEEE 802.3 protocol
expects each frame to be transmitted within one slot time (the expected
time for a 512 bit frame 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:
A network that is too long.
Broken 100Base-T cards in the network.
A network can be made too long by installing too many repeaters between
nodes. The 100Base-T card hardware detects collisions after the
512 bit timer expires even though IEEE 802.3 standards do not require
the link to be monitored beyond that time. The maximum value of
this 32-bit field is 2147483647. This statistic is not logged when
the adapter card is operating in full duplex mode, and would print as 0.
Trans underruns — Total number
of frames aborted by the adapter card during transmission because
the remaining data was not made available to the transmit hardware
fast enough. It indicates unexpected latency on the dedicated internal
bus onboard the adapter card. If this condition occurs, the adapter
will automatically adjust to improve the latency, and retransmit
the aborted frame automatically. The maximum value of this 32-bit
field is 2147483647. For this statistic, a value of less than 3
would be considered normal.
Carrier losses — This field
indicates that the transmitting node turned off the carrier signal
on the cable. A carrier loss occurs when a receive carrier was not
detected after a slottime from the start of transmission. The carrier
must be present continuously from the start until the end of transmission
to prevent an error. If the 100Base-T link continuously loses carrier,
the problem is probably caused by a faulty hub or cable, or a disconnected
cable somewhere else within the network, along the path between
the target nodes. The maximum value of this 32-bit field is 2147483647.
This statistic is not logged when the adapter card is operating
in full duplex mode, and would print as 0.
NOTE: The PCI 100Base-T adapter card reports both "loss
of carrier" (during transmission) and "no carrier" (no
carrier detected at start of transmission) as distinct events. For
PCI, the "carrier losses" statistic represents
the sum of the "no carrier" and "loss of carrier" events.
Trans jabber timeouts — The
number of times the adapter card transmitted onto the LAN for too
long, and had to be forced to stop. This should only occur if the
adapter card or hub are faulty. The maximum value of this 32-bit
field is 2147483647. This statistic is displayed for PCI 100Base-T only.
Link disconnects — Number
of times the link driver noticed the link had previously been established,
but was no longer up. This may occur because the cable was unplugged,
the hub was powered off, the hub automatically requested a reconnect,
or normally (at link shutdown time). This total does not include
repetitive, failed attempts by the link driver to reestablish the
link. The maximum value of this 32-bit field is 2147483647.
Link speed — Maximum link
speed (either 100 or 10) in million bits per second, the link is
currently configured to operate at. When displaying a 100Base-T
link operating in 100Base-T mode, this value will always be 100.
When a 100Base-T link is operating in 10Base-T mode, this value
will always be 10.
Link mode — Electrical mode
the link is currently operating at. When displaying a 100Base-T
link operating in 100Base-T mode, this value will always be "100Base-T".
When it is operating in 10Base-T mode, this value will be "10Base-T".
For PCI, the type of card (e.g., "Addon") may
also be shown here.
Receive bytes — Total number
of bytes successfully received over the medium. This includes unicast,
multicast, broadcast, and 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 64-bit field is 17 digits, or about 99
million Gbytes. In the previous example, 495 million bytes were
received, or about 472 Mbytes.
Receives / Receives Unicast — Total
number of unicast frames (addressed to this specific adapter card)
which were successfully received over the medium and forwarded to
an upper layer protocol such as IP. This includes unicast frames
that were successfully received on the first attempt, as well as
unicast frames that were successfully received after being deferred,
or that experienced one or more collisions. It does not include
unicast frames received but dropped for any reason. The maximum
printable value of this 64-bit field is 17 digits, or about 99 million
billion frames. In the previous example, 113968 unicast frames were
received and forwarded to upper layers.
NOTE: This has been renamed "Receives Unicast" in
the PCI statistics display to better distinguish this statistic
from the other receive statistics, but the meaning is the same as before.
Receives broadcast — Total
number of frames addressed to a broadcast address which were successfully
received over the medium and forwarded to an upper layer protocol
such as IP. This includes broadcast frames that were successfully
received on the first attempt, as well as broadcast frames that
were successfully received after being deferred, or that experienced
one or more collisions. It does not include broadcast frames received
but dropped for any reason. The maximum printable value of this
64-bit field is 17 digits, or about 99 million billion frames. In
the previous example, 3.96 million broadcast frames were received
and forwarded to upper layers.
Receives multicast — Total
number of frames addressed to a multicast address which were successfully
received over the medium and forwarded to an upper layer protocol
such as IP. This includes multicast frames that were successfully
received on the first attempt, as well as multicast frames that
were successfully received after being deferred, or that experienced
one or more collisions. It does not include multicast frames received
but dropped for any reason. The maximum printable value of this
64-bit field is 17 digits, or about 99 million billion frames. In
the previous example, 1.74 million multicast frames were received
and forwarded to upper layers.
Receives no error — Total
number of frames the adapter card reports it successfully received
over the medium. These adapter card statistics are periodically
read, and are accumulated by the link driver. This includes all
address-matched unicast, broadcast, and multicast frames received
without error. It does not include frames not addressed to the adapter
card, frames dropped for any reason, or any frames the card detected
errors against. The total should approximate the sum of all frames
forwarded to upper layer protocols. The maximum printable value
of this 64-bit field is 17 digits, or about 99 million billion frames. In
the example above, 15.7 million frames were received successfully
by the adapter card, then either forwarded or dropped.
CRC or Maxsize error — Number
of cyclic redundancy check (CRC) errors or oversized frames that
were seen during reception by 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
at the end of the frame. CRC errors do not include frames having
alignment or coding errors. Oversized frames are those longer than
1518 bytes. These adapter card statistics are periodically read,
and are accumulated by the link driver. The maximum value of this
32-bit field is 2147483647. A nonzero value in this statistic could
indicate a defective cable, adapter, or hub, a loose connection,
presence of severe electrical noise along the cable path, or a misbehaved
application, adapter, or hub at the transmission end. For PCI 100Base-T,
these statistics (CRC error, Maxsize error) are reported separately
by the adapter card and are displayed separately (Recv CRC error,
Recv Maxsize error).
Code or Align error — Number
of frames received with an alignment error (not an even multiple
of 4 bits of data) or code errors (an error signal was received
from the 100Base-T receive hardware). These adapter card statistics
are periodically read, and are accumulated by the link driver. The
maximum value of this 32-bit field is 2147483647. This statistic
is not applicable to PCI and is not displayed for PCI 100Base-T
links. If alignment errors occur frequently, one of the following
may be the cause:
A 100Base-T adapter card is not operating to within 802.3
specifications.
A 100Base-T hub is performing poorly.
The 100Base-T cable is not CAT-5 grade.
A section of 100Base-T cable contains wire pairs which are not
properly twisted, paired, or of equal length.
Recv dropped: addr — Total
number of frames received by the adapter card, but dropped because
no upper layer protocol had requested future reception of those
frames, or because that protocol unbound itself from the link while
the received frame was still in motion. Older, intelligent adapter
cards can invisibly receive and drop these frames, often without
ever reporting them as statistics. But today's adapters
are not intelligent, and require link driver involvement. For users
unfamiliar with seeing it, this statistic may seem excessive. But
it is important because it gives an indication of the amount of
unnecessary traffic present on the network segment to which the
adapter card is connected. High values may indicate a need to resegment
the network, since systems and their adapters are spending a large
amount of time and resources recognizing and dropping frames they
do not care to see. High volumes of such traffic can also limit network
bandwidth. The maximum printable value of this 64-bit field is 17
digits, or about 99 million billion frames. In the previous example, out
of 15.7 million frames received, 9.87 million have been dropped based
on address: about 63 percent of all frames received are then being dropped.
This level would be considered high.
Recv dropped: buffer — Total
number of frames received from the adapter card, but dropped because
no data buffers were available from the upper layer protocol requesting
to receive these frames. This is a relatively common occurrence,
amounting to flow control for all protocols sharing those buffers.
Many protocols include built-in mechanisms for detecting lost frames
and requesting their retransmission from the remote side. The maximum
value of this 32-bit field is 2147483647. In the previous example,
out of 66.4 million frames received, 262 have been dropped for lack
of buffer resources; any similar level would be considered normal.
Recv dropped: dma — The link
driver design now queues frames under conditions of low DMA resources,
so this statistic is now obsolete, should never contain a nonzero
value, and may be deleted in a future release. This statistic is
not applicable to PCI and is not displayed for PCI 100Base-T links.
Recv dropped descr — Total
number of times the adapter card reported it was unable to receive
a frame because of a problem with the receive instructions specified
by the software driver. The maximum value of this 32-bit field is
2147483647. It would be unusual for this statistic to contain a
nonzero value. This statistic is only applicable for PCI 100Base-T links.
Recv dropped: other — Sum
total number of frames received from the adapter card, but dropped
because: an upper layer protocol error was returned; the required
address format was not supported; the frame arrived while the link
driver was in an unusual state; or for perfect multicast filtering
reasons. The maximum value of this 32-bit sum is 2147483647. In
the previous example, 24785 frames have been dropped for one or
more of the reasons listed; this number would be considered high,
and further investigation might be needed if it appears to be impacting
any applications.
Recv deferred — Number of
times an address-matched receive frame was temporarily held (queued)
by the link driver, because of a momentary lack of DMA resources.
Once those resources became available, the frame was automatically
transferred to the host. The maximum printable value of this 64-bit
field is 17 digits, or about 99 million billion frames. In the previous
example, 123 frames were temporarily held. This statistic is not
applicable to PCI and is not displayed for PCI 100Base-T links.
Recv overruns — Total number
of address-matched frames that could not be received into the adapter
card, either because prior data was not being removed by the receive
hardware fast enough, or because their size exceeded the maximum
frame size. May indicate unexpected latency on the dedicated internal
bus onboard the adapter card, which cannot be automatically adjusted
by the link driver. The maximum value of this 32-bit field is 2147483647.
It would be unusual for this statistic to contain a nonzero value.
The following receive statistics are only applicable for PCI 100Base-T links:
Recv watchdg timeout — The
number of times the adapter card tried to receive from the LAN for
too long, and had to be forced to stop. This should only occur if
the adapter card, the hub, or another adapter card on the network,
are faulty. The maximum value of this 32-bit field is 2147483647.
Recv collisions — This field
indicates that a frame was active in the network for a longer time
than is permitted by the protocol, and damaged a frame being received.
No attempt is made to re-receive a frame damaged by a late collision.
The IEEE 802.3 protocol expects each frame to be transmitted within
one slot time (the expected time for a 512 bit frame 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:
A network that is too long.
Broken 100Base-T cards in the network.
A network can be made too long by installing too many repeaters between
nodes. The 100Base-T card hardware detects receive collisions occurring
after the 512 bit timer expires even though IEEE 802.3 standards
do not require the link to be monitored beyond that time. The maximum
value of this 32-bit field is 2147483647. This statistic is not logged
when the adapter card is operating in full duplex mode, and would
print as 0. Not applicable to HP-PB.
Link auto sensed — A value
of Yes indicates the local adapter card attempted to autonegotiate
its speed and duplex settings, and the remote side returned a set
of remote capabilities to the local adapter card, meaning the remote
also supports the autonegotiation feature. The "Link speed" and "Link
mode" fields report the settings chosen by the two sides.
A value of No indicates the remote side did not return a set of
capabilities although the local adapter card attempted to autonegotiate,
and the "Link speed" and "Link mode" fields
report the driver's best-guess settings. "No" is
also shown when the local adapter card is configured in NMCONFIG
to use fixed speed and duplex settings.
Secs since clear — The number of seconds elapsed since statistics
were last reset via the LINKCONTROL linkname;
STATUS=RESET command. This gives the sample time over which the displayed
statistics have been collected. Per-time-unit figures may then be calculated
if desired. The maximum value of this 32-bit field is 2147483647,
or about 68 years.
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