A port in a LAN configurationconsists of a protocol type, a service access point (SAP) or protocolidentifier, and a controller. There are as many ports on a LAN controlleras there are protocol types, SAPs, and protocol identifiers. Eachport is independent of other ports running on the same LAN controller.
Application programs use either the LAN driver's QIO interfaceor VCI interface to perform I/O operations to and from other nodeson the LAN. This chapter describes the QIO interface. Typical Ethernet Configuration shows the relationship of most Ethernetcontrollers to the processor and to the user application program.
Figure 2 Typical Ethernet Configuration
Driver Initialization and Operation Thefollowing sequence initializes and starts a port on a LAN devicedriver:
Use the AssignI/O Channel ($ASSIGN) system service to assign I/O channels to oneor more of the LAN device names and devices specified in Supported OpenVMS VAX Systems LAN Devices and Supported OpenVMS Alpha LAN Devices. $ASSIGN creates a new unit control block (UCB),to which the channel for the port is assigned.
Start up the port with the set mode function andstartup function modifier (see Set Controller Mode). You must supply the required P2 buffer parameters listedin P2 Attributes.
Perform read, write, and sense mode operations asneeded.
Shut down the port with the set mode function andshutdown function modifier (see Shutdown Controller).
Use the Deassign I/O Channel ($DASSGN) system serviceto deassign the I/O channel.
HP OpenVMS I/O User's Reference Manual
Local Area Network (LAN) Device Drivers
