1  –  link

    set  [node node-id] hdlc link link-name ...

    Modifies the attributes for an hdlc link entity, which is
    associated with a port of the supporting physical layer module.
    It contains attributes common to local HDLC operations for all
    logical stations on the line.  The modifiable attributes and
    their data types [in brackets] are:

    acknowledge timer [milliseconds]
    holdback timer [milliseconds]
    maximum data size [integer]
    maximum unsequenced pdus [integer]
    minimum data size [integer]
    physical line [local-entity-name]
    preferred crc type [CRC-type]
    preferred local station address [integer]
    preferred maximum data size [integer]
    preferred window size [integer]
    receive buffers [integer] (OpenVMS)
    retry maximum [integer]
    sequence modulus [8 or 128]

1.1  –  acknowledge_timer

    Default: 3000          Value: 1-60000

    Time, in milliseconds, to wait for an acknowledgment before using
    error recovery procedures. The value of this characteristic
    corresponds to the T1 parameter of HDLC. You can modify this
    characteristic only when the entity is disabled.

1.2  –  holdback_timer

    Default: 0             Value: 1-60000

    Maximum time to wait before sending an acknowledgment supervisory
    frame if no other frames carry the acknowledgment. A value of
    zero means that the frame will be sent immediately if no I-frame
    can be sent. You can modify this characteristic only when the
    entity is disabled.

1.3  –  maximum_data_size

    Default: 1500          Value: 262-65532

    Maximum number of bytes that users of the data link can specify.
    This number applies to both transmit and receive frames.

    The value of this characteristic must be greater than or equal to
    the value of the minimum data size characteristic. You can modify
    this characteristic only when the entity is disabled.

1.4  –  maximum_unsequenced_pdus

    Default: 1             Value: 1-127

    Maximum number of unsequenced I-frames that a primary or
    secondary station can send in a single transmission. This
    characteristic is not used if the link type characteristic is
    balanced.

1.5  –  minimum_data_size

    Default: 576           Value: 262-65532

    Minimum number of bytes that users of the data link can specify.
    This number applies to both transmit and receive frames.

    The value of this characteristic must be less than or equal to
    the value of the maximum data size characteristic. You can modify
    this characteristic only when the entity is disabled.

1.6  –  physical_line

    Default: None          Value: Local entity name

    Local entity name of the the Physical layer entity over which the
    HDLC protocol is to operate.

    This characteristic must have a value before the HDLC link is
    enabled. You can modify this characteristic only when the entity
    is disabled.

1.7  –  preferred_crc_type

    Default: Either        Value: 16 bit, 32 bit, or either

    CRC types available for negotiation. If the value of this
    characteristic is either, the station will try to use 32-bit but
    will use 16-bit if that is all that the remote station supports.

1.8  –  preferred_local_station_address

    Default: 2             Value: 1-253

    Address proposed for the local logical station during
    negotiation. If there is no negotiation, the value of this
    characteristic is the value that is used. If negotiation is
    necessary, the value of this characteristic must be between 2
    and 253. You can modify this characteristic only when the entity
    is disabled.

1.9  –  preferred_maximum_data_size

    Default: 1500          Value: 262-65532

    Default size (in octets) of frames that the station receives and
    transmits. This value is used only if the link initialization
    does not specify a buffer value.

    The value of this characteristic must lie between those of the
    maximum data size and minimum data size characteristics. You can
    modify this characteristic to a lower value only when the entity
    is disabled.

1.10  –  preferred_window_size

    Default: 2             Value: 1-127

    Window size to be offered during negotiation for both receive
    and transmit frames. The value of this characteristic must be
    compatible with that for the sequence modulus characteristic.

1.11  –  receive buffers (OpenVMS)

    Default: 4             Value: 1-128

    Number of receive buffers reserved for the link. This
    characteristic can only be set to a lower value when the entity
    is disabled.

1.12  –  retry_maximum

    Default: 10            Value: 1-255

    Maximum number of times that a frame will be retransmitted before
    the local station assumes that a fatal error has occurred. This
    characteristic can be modified only when the entity is disabled.

1.13  –  sequence_modulus

    Default: 128           Value: 8 or 128

    Whether modulo-8 or modulo-128 sequence numbering is allowed
    on the HDLC link. The value 8 means that only normal sequence
    numbering is allowed. The value 128 means that both extended and
    normal sequence numbering are supported for negotiation.