11.1.1 Address Structures

DLPI uses data link service access point (DLSAP) addresses. These are used when connecting to a given address by the DL_CONNECT_REQ, DL_CONNECT_CON and DL_CONNECT_IND primitives. Addressing is handled differently for LLC2 and LAPB.

11.1.1.1 LLC2 Address Structure

The LLC2 DLSAP is contained in the following structure:

struct llc_dladdr {
    u_char   dl_mac[6];      /* MAC address */
    u_char   dl_sap;         /* LLC SAP */
 };

The file /usr/include/netdlc/llc2.h contains the structure definition.

The members of the llc_dladdr structure are:

Table 11-6 Members of llc_dladdr structure

Members	Description
dl_mac	The MAC address
dl_sap	The LLC SAP (service access point).

11.1.1.2 LAPB Address Structure

The address field is only required when LAPB is being used over a Public Switched Telephone Network (PSTN). In this case, the dl_address fields contain the PSTN address, in the format defined by the pstnformat structure:

struct pstnformat {
   uint8   pstn_len;               /* Address length in octets */
   uint8   pstn_add[20];  /* LAPB Address in hexadecimal */
 };

The members of the pstnformat structure are:

Table 11-7 Members of pstnformat structure

Members	Description
pstn_len	The length of the address as bytes.
pstn_add	The LSAP in hexadecimal format. This can be up to 20 digits long.

The file /usr/include/netx25/sdlpi.h contains the structure definition.