DECnet-Plus
Network Control Language Reference

For enable:

device constraint

open physical port failure

Arguments:

reason	Specifies why the open operation failed.
	invalid argument	The open port call was improperly formed.
	line not available	The line managed by the Physical layer entity is already allocated to another data link entity. Modify the physical line characteristic to specify an entity not used by any other data link entity, then reissue the enable command.
	no such line	The entity specified in the physical line characteristic does not exist. Either create that entity, or modify the value of physical line to name an entity that does exist. Then reissue the enable command.

Note

Only the DSF32 device supports SWIFT and CHIPS framing.

11.3 frame port

name

Simple name assigned to the port when it is created.

client

Name of the client entity that opened the port.

link

Name of the frame link entity that the client supplied when the port was opened.

state

State of the frame port entity.

open	The port is assigned to a client.
open disabled	The port is assigned to a client, but the appropriate link entity has been disabled.

This chapter describes all the commands you can use to manage the entities that constitute the HDLC module. The HDLC module implements one of the protocols in the Data Link layer. The HDLC (High-level Data Link Control) protocol is intended to cover a wide range of applications. This includes one-way, two-way alternate or two-way simultaneous data communication between data stations that are usually buffered, including operations on different types of data circuits; such as, multipoint/point-to-point, duplex/half-duplex, and switched/non-switched. This implementation uses HDLC to offer reliable communication at the Data Link layer for point-to-point synchronous data lines over a wide area network link. The HDLC module typically runs as a Data Link module under the CLNS (Connectionless-Mode Network Service) network protocol.

Figure 12-1 shows the hierarchical relationship of the entities that constitute the HDLC module.

Figure 12-1 Hierarchy of HDLC Module Entities

12.1 hdlc

version

Version of the HDLC architecture specification to which the implementation conforms. You cannot modify this characteristic.

12.2 hdlc link

linktype link-type

Operational mode of the HDLC link, determining how the logical station operates. This value is negotiated with the remote station. This argument determines the value of the link type characteristic.

balanced	The logical station operates in asynchronous response balanced mode. This is the default value of the argument.
primary	The logical station is the primary and operates in normal response mode.
secondary	The logical station is a secondary and operates in normal response mode.

profile latin1string

A string of information that can be used when the HDLC protocol is dependent on network subscription time commitments pertinent to the Data Link layer. When specified, the values of some link characteristics may be overridden. This argument determines the value of the profile characteristic. The default value of this argument is a null string, meaning that no profile is used.

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.

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.

link type

Operational mode of the HDLC link. The value of this characteristic is a copy of the link type argument specified when the entity is created. You cannot modify this characteristic.

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.

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.

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.

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.

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.

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.

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.

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.

profile (OpenVMS)

Simple name that can be used when the HDLC protocol is dependent on network subscription time commitments pertinent to the Data Link layer. The value of this characteristic is a copy of the profile argument specified when the entity is created. You cannot modify this characteristic.

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.

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.

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.

buffer unavailable errors (OpenVMS)

Number of times the Physical layer reported that no buffer was available to hold a message. This counter is not supported in all implementations.

crc errors received

Number of frames received that had a bad CRC.

creation time

Time at which this entity was created.

times pdu receive overrun

Number of times a physical line indicated an overrun condition to the Data Link layer. This counter is not supported in all implementations.

times pdu transmit failed

Number of times an attempt to send a frame failed.

up transitions

Number of times the entity's status attribute state has changed from off to on.

name

Simple name assigned to the HDLC link when it is created.

actual sequence modulus

Sequence number modulus in use on the link. Until negotiation is complete, this attribute has the value 128. However, if the value of the characteristic sequence modulus is 8, the modulus always appears as the value 8.

8	Indicates that modulo-8 numbering is in use. Allows frame sequence values 0 through 7.
128	Indicates that modulo-128 numbering is in use. Allows frame sequence values 0 through 127.

interframe delay

Default: None

Value: 0-- 10^ 9

Time required between frames to enable the local station to successfully receive them.

line type

Default: None

Value: Switched or nonswitched

Defines whether the underlying physical line is switched or nonswitched. This status affects the subset of port states that are related to a given link.

maximum pdu size

Default: None

Value: 1--65535

Maximum frame size (in octets) that can be used on the link. Until negotiation is complete, the value of this status attribute is the same as the characteristic preferred maximum data size.

negotiated crc type

CRC mode that has been negotiated with the remote station. This mode will not be used until the station is next enabled. Until negotiation is complete, the value of this is 16-bit.

physical port

Name of the port in the Physical layer associated with the communications link.

response address

Address that the remote station puts in response frames.

state

State of the HDLC link. This reflects the last enable or disable command issued.

off	The link is disabled.
on	The link is enabled.

uid

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

window size

Default: None

Value: 1--127

Maximum number of I-frames that can be outstanding before an acknowledgment must be received. Until negotiation is complete, the value of this status attribute is the same as the characteristic preferred window size.

buffer unavailable error (OpenVMS)

Generated each time a frame is discarded because there is no receive buffer available.

link down

Generated each time the entity is disabled.

link up

Generated each time the entity is enabled.

pdu receive overrun

Generated each time the Physical layer entity reports a receive overrun.

pdu transmit failed

Generated each time an attempt to send a frame fails.

Argument:

pdu transmit failed reason	Failure reason received from the Physical layer entity.
	disabled	The network manager has disabled the line.
	line down	The line is in the failed state.
	no service	The Physical layer service is not available.

For delete:

has children

Cannot delete while subentities exist.

link enabled

The link is still enabled. Disable the link and reissue the delete command.

wrong state

Failure to delete the hdlc link logical station subentity because the logical station must be disabled before deletion.

For enable:

client data size not supportable

Client's buffer size is larger than the HDLC software can support.

incompatible communications mode

The value of the link type argument specified in the create command is incompatible with the actual type of link.

Argument:

reason	Feature of the line that is incompatible with the link type.
	CRC mode not supported	The line does not support CRC selected by the preferred CRC type characteristic attribute.
	full-duplex mode	The line is full-duplex and the link type is primary/secondary.
	half-duplex mode	The line is half-duplex and the linktype is balanced.
	protocol not supported	The line does not support HDLC framing.

Correct the value of the link type argument, or use a line that supports the appropriate protocol. Then reissue the enable command.

open physical port failed

Attempt to open a port to the Physical layer failed.

Argument:

reason	Specifies why the Physical layer rejected the open operation.
	invalid argument	The call to the Physical layer was improperly formed.
	insufficient resources	The Physical layer had insufficient system resources to be able to open the port.
	line not available	The line specified as the value to the physical line characteristic is already allocated to another entity in the Data Link layer. Change the value of the physical line characteristic to an unused line, and reissue the enable command.
	no such physical line	The entity specified in the physical line characteristic does not exist. Check the value of the characteristic and, if necessary, change it to the correct name, then reissue the enable command. If the name is correct, create the necessary Physical layer entity and then reissue the enable command.

12.3 hdlc link logical station

limit

Limits station exclusively to unsequenced data service.

unlimit

Enables sequenced and unsequenced data service.

creation time

Time at which this entity was created.

data octets received

Total number of octets received in the I-field of I-frames and UI-frames. This total excludes protocol ID information in UI-frames and frame retransmissions.

data octets sent

Total number of octets sent in the I-field of I-frames and UI-frames. This total excludes protocol ID information in UI-frames and frame retransmissions.

data pdus received

Total number of I-frames and UID-frames received. This number does not include frames that had to be retransmitted.

data pdus sent

Total number of I-frames and UID-frames sent. This number does not include frames that had to be retransmitted.

frmrs generated

Number of FRMRs (frame rejects) sent.

frmrs received

Number of FRMRs (frame rejects) received.

invalid mode commands

Number of command frames (SABME, SABM, SNRME, SNRM, SARM, and SIM) received that are not applicable to this station.

negotiation failures

Number of times that the XID negotiation with the remote station has failed.

polls received

Number of frames received with the poll bit set.

rejs received

Number of REJ frames (rejects) received.

rejs sent

Number of REJ frames (rejects) sent.

rnrs received

Number of RNR (receive not ready) supervisory frames received from the remote station.

rnrs sent

Number of RNR (receive not ready) supervisory frames transmitted.

times acknowledge timer expired

Number of times the acknowledge timer has expired.

times station halted

Number of times the station halt event has occurred.

times station initializing

Number of times the station initialized event has occurred.

times station inoperative

Number of times the entity's status attribute state became inoperative.

times station maintenance

Number of times the entity's status attribute state became maintenance.

times station resetting

Number of times the station reset event has occurred.

times station running

Number of times the station running event has occurred.

times station setup failed

Number of times the station setup failure event has occurred.

unknown ui pdus received

Number of UI-frames the local station received whose protocol ID does not match that of any open port.

xids received

Number of XID (identification) command or response frames received.

name

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

command address

Address the local station uses when sending command frames to the remote station.

maintenance mode

Whether the station is in maintenance mode. When set to true, the station will be used exclusively for maintenance operations. When set to false, the station operates in normal fashion.

The limit command sets the value of this attribute to true, and the unlimit to false.

protocol state

State of the data link protocol.

error	A protocol error occurred. For instance, the logical station received an invalid frame.
halted	The protocol could not start. For example, there is no client.
initializing	The protocol is being initialized.
inoperative	The protocol cannot be started because no contact has been established with the remote station.
maintenance	The logical station is in maintenance mode.
resetting	The protocol is resetting after an error.
running	The protocol is running and capable of exchanging frames with the remote station.

remote version

Version number of the HDLC protocol that the remote station is using. This is received as part of an XID message from the remote station.

state

State of the logical station.

off	The logical station is off because of a disable command.
on	The logical station is on because of an enable command.

uid

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

12.3.5 Event Messages

frmr generated

Generated each time the logical station rejected a received frame.

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