NCLHELP.HLB  —  show  ddcmp (OpenVMS VAX), link
    show [node node-id] ddcmp -
                link link-name  attribute [,attribute...]
                                all [attributes]
                                all characteristics
                                all counters
                                all identifiers
                                all status

    Examples:

    show ddcmp link * name

    show ddcmp link ddcmp-0 all char

1  –  Characteristics

 o  dead timer

    Default: 10000         Value: 1-65535

    Specifies the delay, in milliseconds, between polls of one of the
    set of dead tributaries. This attribute is supported only if the
    characteristic protocol is set to control.

 o  delay timer

    Default: 0             Value: 0-65535

    Specifies the minimum delay, in milliseconds, between polls. You
    can use this timer to limit the effect of a fast control station
    on slower tributaries. A value of 0 means that no delay is added.
    This attribute is supported only if the characteristic protocol
    is set to control.

 o  physical line

    Default: No name       Value: Local entity name

    Name of the Physical layer entity that the link operates over. A
    value for this characteristic must be set before the link entity
    is enabled. You can modify this characteristic only when the
    entity is disabled.

 o  protocol

    Default: Point         Value: See following description

    Protocol mode used by the local station. You cannot modify this
    characteristic.

    The value of this characteristic is a copy of the protocol
    argument specified when the ddcmp link entity is created. The
    default value is point and is the only permissible value.

 o  receive buffers

    Default: 4             Value: 1-255

    Specifies the number of receive buffers reserved for the link.
    You can modify this characteristic only when the entity is
    disabled. Also, you can only increase the characteristic value.

 o  retransmit timer

    Default: 3000          Value: 1-65535

    Maximum time (in milliseconds) to wait between sending a message
    and receiving a valid response. If this time expires, the local
    station takes error recovery action. On full-duplex point-to-
    point links, the timer is started immediately when a message is
    sent.

 o  scheduling timer

    Default: 200           Value: 50-65535

    Specifies the time, in milliseconds, between the recalculation of
    tributary polling priorities. This attribute is supported only if
    the characteristic protocol is set to control.

 o  stream timer

    Default: 6000          Value: 0-65535

    Specifies the time, in milliseconds, for which a tributary or
    the remote station (on a half-duplex point-to-point link) can
    hold the line. This characteristic is not supported if the
    characteristic protocol is set to tributary.

2  –  Counters

 o  creation time

    Time at which this entity was created.

 o  naks received indicating message header format error

    Number of NAK messages received that report errors in message
    headers sent from the local station.

 o  naks received indicating receive overrun

    Number of NAK messages received that report a receive overrun at
    the remote station.

 o  pdus received with message header format error

    Number of times the local station detected an error in a message
    header.

 o  receive overruns

    Number of times the local station detected a receive overrun.

 o  selection address errors

    Number of times that the controller of a multipoint link
    received a message with an address other than that of the
    currently selected station. This counter is supported only if
    the characteristic protocol is set to control.

 o  streaming tributaries

    Number of times that the remote station (or a tributary station)
    exceeded the maximum transmission interval without releasing
    the line, or failed to release the line after sending a message
    with the select flag set. This counter is present only on half-
    duplex, point-to-point links, or when the local station is a
    controller of a multipoint link. This counter is not supported if
    the protocol characteristic is set to tributary.

 o  transmit underruns

    Number of times the local station detected a transmit underrun.

3  –  Identifier

 o  name

    Simple name assigned to the link when it is created.

4  –  Status

 o  physical port

    Name of the port entity in the Physical layer returned when the
    port is opened. If this is null, the port is not open.

 o  state

    State of the DDCMP link. The value of this attribute is
    determined by the enable and disable commands.

    off      The entity is disabled.

    on       The entity is enabled.

    In addition the link is disabled and its state set to off if the
    Physical layer port that the link uses is deleted.

 o  uid

    Entity's unique identifier, which is generated when the entity is
    created.

5  –  logical_station

    show [node node-id] ddcmp -
       link link-name -
          logical station station-name  attribute [,attribute...]
                                        all [attributes]
                                        all characteristics
                                        all counters
                                        all identifiers
                                        all status

    The link-name must be a simple name which uniquely represents
    a particular LINK instance.  The station-name can be either
    a simple name which uniquely identifies a particular
    logical station or a wildcard which identifies multiple
    logical stations.

    Examples:

    show ddcmp link ddcmp-0 logical station * name
    show ddcmp link ddcmp-0 logical station ddcmp-0 all

5.1  –  Characteristics

 o  active base

    Default: 255           Value: 0-255

    Specifies the base priority to which an active tributary is reset
    after it has been polled.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  active increment

    Default: 0             Value: 0-255

    Specifies the value to be added to the active tributary priority
    each time the scheduling timer expires.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  address

    Default: 1             Value: 1-255

    Data link address of the remote station or tributary. You can
    modify this characteristic only when the entity is disabled.

 o  babble timer

    Default: 6000          Value: 1-65535

    Specifies the time, in milliseconds, for which a selected
    tributary or remote station is allowed to transmit. This
    characteristic is not used on full-duplex links.

    This characteristic is not supported if the characteristic
    protocol of the owning ddcmp link entity is set to tributary.

 o  buffer source

    Default:  Implementation-specific    Value: See description

    Specifies the source of the receive buffers.

    client         Buffers are provided by the client entity.
    supplied

    common pool    Buffers are assigned from the common buffer pool.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control. You
    can modify this characteristic only when the entity is disabled.

 o  dead threshold

    Default: 8             Value: 0-255

    Specifies the number of times that an active, inactive, or dying
    tributary is polled before its status attribute polling substate
    is changed to dead because of receive timeouts.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  dying base

    Default: 0             Value: 0-255

    Specifies the base priority to which a dying tributary is reset
    after being polled.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  dying increment

    Default: 16            Value: 0-255

    Specifies the value to be added to a dying tributary's priority
    each time the scheduling timer expires.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  dying threshold

    Default: 2             Value: 0-255

    Specifies the number of times an active or inactive tributary is
    polled before its status attribute polling substate is changed to
    dying because of receive timeouts.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  holdback timer

    Default: 0             Value: 0-13000

    Maximum time (in milliseconds) that the local station can delay
    acknowledging a received message if there is no data to send.

    The value of this characteristic is linked to the retransmit
    timer used on the remote station. A suggested value is between
    10% and 20% of that timer. However, the actual values you can use
    may be limited by the communications product.

    The default value indicates that no holdback is used and the
    local station must acknowledge immediately.

 o  inactive base

    Default: 0             Value: 0-255

    Specifies the priority to which an inactive tributary is reset
    after it has been polled.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  inactive increment

    Default: 64            Value: 0-255

    Specifies the value to be added to an inactive tributary's
    priority each time the scheduling timer expires.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  inactive threshold

    Default: 8             Value: 0-255

    Specifies the number of times an active tributary is polled
    before its status attribute polling substate is changed to
    inactive because of no data response.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  maximum buffers

    Default: 4             Value: Implementation specific

    Specifies the maximum number of buffers that a tributary can
    use from the common buffer pool. A value of 0 means that
    there is no limit to the number of buffers that can be used.
    This characteristic is supported only if the buffer source
    characteristic is set to common pool.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control. You
    can modify this characteristic only when the entity is disabled.
    Also, you can only increase the characteristic value.

 o  maximum transmit

    Default: 4             Value: 1-255

    Specifies the maximum number of messages that a tributary or a
    remote half-duplex station can send at one time. The value of
    this characteristic must be greater than or equal to that of
    transmit window on the selected station.

    This characteristic is not supported if either of the following
    conditions is true:

    o  The characteristic protocol of the owning ddcmp link entity is
       set to tributary.

    o  The communications link is full-duplex and point-to-point.

    You cannot modify this characteristic.

 o  polling state

    Default: Automatic     Value: See description.

    Specifies the effect of the local station's polling algorithm
    on the state of a tributary. The value of this characteristic is
    reflected in the value of the status attribute polling substate.

    active     The state is locked to active.

    automatic  The state varies according to the operation of the
               polling algorithm.

    dead       The state is locked to dead.

    dying      The state is locked to dying.

    inactive   The state is locked to inactive.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  transmit timer

    Default: 0             Value: 0-65535

    Specifies the time, in milliseconds, that the local station waits
    between data transmissions.

    This characteristic is supported only if the characteristic
    protocol of the owning ddcmp link entity is set to control.

 o  transmit window

    Default: 1             Value: 1-255

    Specifies the maximum number of data messages that the local
    station can send without receiving an acknowledgment. This
    characteristic applies only when the remote station is a control
    station or on a half-duplex, point-to-point link. The value of
    this characteristic must be less than or equal to the equivalent
    of the maximum transmit characteristic on the control station or
    remote station.

5.2  –  Counters

 o  buffers temporarily unavailable

    Number of times the local station could not service messages
    from the remote station because there were no receive buffers
    available.

 o  buffers too small

    Number of times the local station could not service messages from
    the remote station because the receive buffers were not large
    enough.

 o  creation time

    Time at which this entity was created.

 o  incomplete replies to select

    Specifies the number of selection intervals that were not
    properly terminated (that is, by a message with the Select bit
    set in the header), during which a transmission was received or
    an attempt at transmission was detected.

    This counter is supported only if the protocol characteristic of
    the owning ddcmp link entity is set to control, or when the link
    is a half-duplex point-to-point link.

 o  local reply timeouts

    Number of times the local station failed to receive an
    acknowledgment before the reply timer expired.

 o  locally initiated state changes

    Number of times that the station protocol state changed through
    action of the local station.

 o  naks received indicating buffer too small

    Number of times the remote station reported that it could not
    service a message because the receive buffer was not large
    enough.

 o  naks received indicating buffers temporarily unavailable

    Number of times the remote station reported that it could not
    service a message because no receive buffer was available.

 o  naks received indicating data field block check error

    Number of times the remote station reported that a block check
    error was detected in the data field of an incoming message.

 o  naks received indicating header block check error

    Number of times the remote station reported that a block check
    error was detected in the header block of an incoming message.

 o  naks received indicating rep response

    Number of times the remote station reported that it did not
    receive all the messages sent from the local station.

 o  naks sent with rep response

    Number of times that the local station detected that not all
    of the messages sent from the remote station were received
    correctly.

 o  no replies to select

    Specifies the number of times that the select timer expired for
    any of the following reasons:

    o  No valid control message was received.

    o  No valid header to a data message was received.

    o  No valid header to a maintenance message from the selected
       station was received.

    o  No transmission from the remote station was received.

    This counter is supported only if the protocol characteristic of
    the owning ddcmp link entity is set to control, or when the link
    is a half-duplex point-to-point link.

 o  pdus received with data field check block error

    Number of messages received with a check error in the data field.

 o  pdus received with header block check error

    Number of messages received with a check error in the header
    block.

 o  receive error thresholds reached

    Number of times that the receive error threshold has been
    reached.

 o  remote reply timeouts

    Number of times the local station received a REP message and
    sent an acknowledgment in return. This sequence indicates that
    all messages sent from the remote station have been correctly
    received.

 o  remotely initiated state changes

    Number of changes in the station protocol state caused by action
    of the remote station.

 o  sdu octets received

    Number of data octets received from the remote station.

 o  sdu octets sent

    Number of data octets sent to the remote station.

 o  sdus received

    Number of data messages received from the remote station (not
    including retransmissions).

 o  sdus sent

    Number of data messages sent to the remote station (not including
    retransmissions).

 o  selection error thresholds reached

    Number of times that the selection error threshold has been
    reached.

    This counter is not supported if the characteristic protocol of
    the owning ddcmp link entity is set to tributary.

 o  selection intervals

    Number of times that the local station selected the remote or a
    tributary station. The counter does not appear if the link uses
    the tributary protocol. In addition, the counter appears only
    when the local station is the control station for a number of
    tributaries, or is operating over a half-duplex point-to-point
    link.

    This counter is supported only if the protocol characteristic of
    the owning ddcmp link entity is set to control, or when the link
    is a half-duplex point-to-point link.

 o  send error thresholds reached

    Number of times that the send error threshold has been reached.

 o  strts received while in maintenance

    Number of times that the local station received a STRT protocol
    message while in the Maintenance state.

5.3  –  Identifier

 o  name

    Simple name assigned to the link logical station when it is
    created.

5.4  –  Status

 o  polling substate

    Specifies the state of a tributary as determined by the polling
    algorithm. This attribute applies only when the value of the
    link's protocol characteristic is set to control. The value of
    this attribute is affected by the value of the characteristic
    polling state. If the characteristic polling state is set to
    automatic, the value of this status attribute reflects the
    current state of the polling algorithm. For all other values of
    the polling state characteristic, the values of both attributes
    are the same.

    active      The tributary is active and responds with data when
                selected.

    dead        The tributary did not respond when selected within
                the appropriate timeout period, when already in
                the Dying or Inactive state. The tributary will be
                ignored until the station reinitializes.

    dying       The tributary, currently in the Inactive or Active
                state, has not responded within the appropriate
                timeout period when selected.

    inactive    The tributary has not sent any data when selected
                by the control station. However, the tributary has
                responded with an appropriate message when selected.

 o  protocol state

    State of the data link protocol with the remote station.

    halted         The protocol is stopped and no messages are being
                   exchanged with the remote station.

    maintenance    The protocol is off line and dealing with
                   maintenance messages only.

    running        The protocol is on line and is exchanging messages
                   with the remote station.

    starting       There is an attempt to initialize the protocol
                   between the local and remote stations. This uses
                   the STRT and STACK PDUs.

 o  state

    Operational state of the local logical station.

    off            The station is disabled.

    on             The station is enabled.

 o  uid

    Entity's unique identifier, which is generated when the entity is
    created.
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