NAME

DL_INFO_ACK (dl_info_ack_t) - this message is sent in response to DL_INFO_REQ; it conveys information about the DLPI stream to the DLS user.

SYNOPSIS

The message consists of one M_PCPROTO message block, which contains the following structure.

typedef struct {
     t_uscalar_t dl_primitive;
     t_uscalar_t dl_max_sdu;
     t_uscalar_t dl_min_sdu;
     t_uscalar_t dl_addr_length;
     t_uscalar_t dl_mac_type;
     t_uscalar_t dl_reserved;
     t_uscalar_t dl_current_state;
     t_scalar_t  dl_sap_length;
     t_uscalar_t dl_service_mode;
     t_uscalar_t dl_qos_length;
     t_uscalar_t dl_qos_offset;
     t_uscalar_t dl_qos_range_length;
     t_uscalar_t dl_qos_range_offset;
     t_uscalar_t dl_provider_style;
     t_uscalar_t dl_addr_offset;
     t_uscalar_t dl_version;
     t_uscalar_t dl_brdcst_addr_length;
     t_uscalar_t dl_brdcst_addr_offset;
     t_uscalar_t dl_growth;
} dl_info_ack_t;

PARAMETERS

dl_primitive

conveys DL_INFO_ACK.

dl_max_sdu

conveys the maximum number of bytes that may be transmitted in a DLSDU. This value must be a positive integer that is greater than or equal to the value of dl_min_sdu.

dl_min_sdu

conveys the minimum number of bytes that may be transmitted in a DLSDU. The value is never less than one.

dl_addr_length

conveys the length, in bytes, of the provider's DLSAP address. In the case of ahierarchical subsequent bind, the length returned is the total length, that is, Physical address + SAP +subsequent address length.

dl_mac_type

conveys the type of medium supported by this DLPI stream¹. Possible values include:

DL_CSMACD

The medium is Carrier Sense Multiple Access with Collision Detection (ISO 8802/3).

DL_TPB

The medium is Token-Passing Bus (ISO 8802/4).

DL_TPR

The medium is Token-Passing Ring (ISO 8802/5).

DL_METRO

The medium is Metro Net (ISO 8802/6).

DL_ETHER

The medium is Ethernet Bus.

DL_HDLC

The medium is a bit synchronous communication line.

DL_CHAR

The medium is a character synchronous communication line (for example, BISYNC).

DL_CTCA

The medium is a channel-to-channel adapter.

DL_FDDI

The medium is a Fiber Distributed Data Interface.

DL_FC

The medium is Fiber Channel.

DL_ATM

The medium is Asynchronous Transfer Mode.

DL_IPATM

The medium is Internet IP over Asynchronous Transfer Mode, RFC 1577.

DL_X25

The medium is X.25 LAPB.

DL_IPX25

The medium is Internet IP over X.25, RFC 1356.

DL_ISDN

The medium is ISDN.

DL_HIPPI

The medium is High Performance Parallel Interface.

DL_100VG

The medium is 100 Based VG Ethernet.

DL_100VGTPR

The medium is 100 Based VG Token Ring.

DL_ETH_CSMA

The medium is capable of both ISO 8802/3 and Ethernet.

DL_100BT

The medium is 100 Base T Ethernet.

DL_FRAME

The medium is Frame Relay LAPF.

DL_MPFRAME

The medium is Multi-Protocol over Frame Relay encapsulation, RFC 1490.

DL_ASYNC

The medium is a bit asynchronous communication line.

DL_LOOP

The medium is a software loopback.

DL_OTHER

Any other medium that is not listed above.

dl_mac_type values above 0x80000000 are available for private or experimental use and will not be defined by this Specification.

dl_reserved

is a reserved field whose value must be set to zero.

dl_current_state

conveys the state of the DLPI interface for the stream when the DLS provider issued this acknowledgement. See Allowable Sequence of DLPI Primitives for a list of DLPI states and an explanation of each.

dl_sap_length

indicates the current length of the SAP component of the DLSAP address. It may have a negative, zero or positive value. A positive value indicates the ordering of the SAP and PHYSICAL component within the DLSAP address as SAP component followed by PHYSICAL component. A negative value indicates PHYSICAL followed by the SAP. A zero value indicates that no SAP has yet been bound. The absolute value of the dl_sap_length provides the length of the SAP component within the DLSAP address.

dl_service_mode

if returned before the DL_BIND_REQ is processed, this conveys which service modes ( connection-mode,connectionless-mode or acknowledged connectionless-mode, or any comibination of these modes) the DLS provider can support. It contains a bit-mask specifying one or more than one of the following values:

DL_CODLS

connection-oriented data link service

DL_CLDLS

connectionless data link service

DL_ACLDLS

acknowledged connectionless data link service.

Once a specific service mode has been bound to the stream, this field returns that specific service mode.

dl_qos_length

conveys the length, in bytes, of the negotiated/selected values of the quality of service (QOS) parameters. Section 5, Quality of Data Link Service , describes quality of service and its associated parameters completely. For connection-mode service, the returned values are those agreed during negotiation. For connectionless-mode service, the values are those currently selected by the DLS user. If quality of service has not yet been negotiated, default values will be returned; these values correspond to those that will be applied by the DLS provider on a connect request in connection-mode service, or those that will be applied to each data unit transmission in connectionless-mode service. If the DLS provider supports both connection-mode and connectionless-mode services but the DLS user has not yet bound a specific service mode, the DLS provider may return either connection-mode or connectionless-mode QOS parameter values.

The QOS values are conveyed in the structures defined in QOS Data Structures. For any parameter the DLS provider does not support or cannot determine, the corresponding entry will be set to DL_UNKNOWN. If the DLS provider does not support any QOS parameters, this length field will be set to zero.

dl_qos_offset

conveys the offset from the beginning of the M_PCPROTO block where the current quality of service parameters begin.

dl_qos_range_length

conveys the length, in bytes, of the available range of QOS parameter values supported by the DLS provider. Forconnection-mode service, this is the range available to the calling DLS user in a connect request. Forconnectionless-mode, this is the range available for each data unit transmission. If the DLS provider supports both connection-mode and connectionless-mode services but the DLS user has not yet bound a specific service mode, the DLS provider may return either connection-mode or connectionless-mode QOS parameter values.

The range of available QOS values is conveyed in the structures defined in QOS Data Structures. For any parameter the DLS provider does not support or cannot determine, the corresponding entry will be set to DL_UNKNOWN. If the DLS provider does not support any QOS parameters, this length field will be set to zero.

dl_qos_range_offset

conveys the offset from the beginning of the M_PCPROTO block where the available range of quality of service parameters begins.

dl_provider_style

conveys the style of DLS provider associated with the DLPI stream (see Physical Attachment Identification). The following provider classes are defined:

DL_STYLE1

The PPA is implicitly attached to the DLPI stream by opening the appropriate major/minor device number.

DL_STYLE2

The DLS user must explicitly attach a PPA to the DLPI stream using DL_ATTACH_REQ.

DLS users implemented in a protocol-independent manner must access this parameter to determine whether the DLS attach service must be invoked explicitly.

dl_addr_offset

conveys the offset of the address that is bound to the associated stream. If the DLS user issues a DL_INFO_REQ prior to binding a DLSAP, the value of dl_addr_len will be 0 and consequently indicate that there has been no address bound.

dl_version

indicates the current version of the dlpi that is supported.

dl_brdcst_addr_length

indicates the length of the physical broadcast address.

dl_brdcst_addr_offset

indicates the offset of the physical broadcast address from the beginning of the PCPROTO block.

dl_growth

conveys a growth field for future use. The value of this field will be zero.

STATE

The message is valid in any state in response to a DL_INFO_REQ.

NEW STATE

The resulting state is unchanged.

Footnotes

1.

Readers should note that the list of data links supported by the interface may be augmented and is published on the World-Wide Web in U019 at http://www.xopen.org (under Sales and Ordering). This Corrigendum will contain relevant additional information such as recognised implementors' agreements/guidelines for common data link providers.