HP 800 HP DLPI Programmer's Guide - Page 174

DLPI Input/Output Controls Supported ioctls After receiving the DL_IOC_HDR_INFO ioctl, DLPI constructs the MAC+LLC header template with Out-Of-Packet (OOP) data template. The OOP data template can be used by transport layer to communicate additional information to DLPI or the driver. In response to DL_IOC_HDR_INFO, DLPI returns the OOP header and the Link Layer header template. The mblk containing the MAC/LLC and OOP header is the last (third) mblk in the M_IOCACK response. The DLS user must renegotiate the feature and request DLPI to build a new header template when it receives a DL_LINK_UP_IND event (see "DL_LINK_UP_IND" on page 69) from DLPI, because the link state changes may be due to the driver feature changes. These changes can impact the header template. NOTE The stream must register for receiving link event notifications. In addition, the stream must rebuild the MAC/LLC header templates on every LINKUP events. The M_IOCTL message block that contains DL_IOC_HDR_INFO is followed by one M_PROTO message block containing the following structure. Format typedef struct { ulong dl_primitive; ulong dl_dest_addr_length; ulong dl_dest_addr_offset; dl_priority_t dl_priority; } dl_unitdata_req_t; Parameters dl_primitive DL_UNITDATA_REQ dl_dest_addr_length Length of the Data Link Service Access Point (DLSAP) address of the destination DLS user. If the destination user is implemented using DLPI, this address is the full DLSAP address returned on the DL_BIND_ACK primitive. 174 Chapter 3