Technical Reference: Communications, Volume 1

write Subroutine Extended Parameters for DLC

Purpose

Provide generic data link control (GDLC) with data types, service access points (SAPs), and link station (LS) correlators.

Syntax

#define    DLC_INFO       0x80000000
#define     DLC_XIDD        0x40000000
#define     DLC_DGRM     0x20000000
#define     DLC_NETD       0x10000000

__ulong32_t sap_corr;
__ulong32_t ls_corr;
__ulong32_t flags;
__ulong32_t dlh_len;
};

Description

An extended write or writex subroutine must be issued by an application or kernel user to provide GDLC with data types, SAPs, and LS correlators.

These DLC extended parameters for the write subroutine are part of the data link control in BOS Extensions 2 for the device manager you are using.

Parameters

sap_corr	Specifies the GDLC SAP correlator of the write data. This field must contain the same correlator value passed back form GDLC in the `gdlc_sap_corr` field when the SAP was enabled.
dlh_len	Not used for writes.
ls_corr	Specifies the GDLC LS correlator of the write data. This field must contain the same correlator value passed back from GDLC in the `gdlc_ls_corr` field when the LS was started.
flags	Specifies flags for the writex subroutine. The following flags are supported: DLC_INFO Requests a sequenced data class of information to be sent (generally called I-frames). This request is valid any time the target link station has been started and contacted. DLC_XIDD Requests an exchange identification (XID) non-sequenced command or response packet to be sent. This request is valid any time the target link station has been started with the following rules: GDLC sends the XID as a command as long as no DLC_TEST, DLC_CONTACT, DLC_HALT_LS, or DLC_XIDD write subroutine is already in progress, and no received XID is waiting for a response. If a received XID is waiting for a response, GDLC automatically sends the write XID as that response. If no response is pending and a command is already in progress, the write is rejected by GDLC. DLC_DGRM Requests a datagram packet to be sent. A datagram is an unnumbered information (UI) response. This request is valid any time the target link station has been started. DLC_NETD Requests that network data be sent. Examples of network data include special modem control data or user-generated medium access control (MAC) and logical link control (LLC) headers. Network data must contain the entire MAC layer packet headers so that the packet can be sent without the data link control (DLC)'s intervention. GDLC only provides a pass-through function for this type of write. This request is valid any time the SAP is open.

Related Information

The write or writex subroutine.

List of Kernel Routines for DLC.

read Subroutine Extended Parameters for DLC.

Generic Data Link Control (GDLC) Environment Overview in AIX 5L Version 5.2 Communications Programming Concepts.