DLC_ENABLE_SAP

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This section explains the ioctl subroutine argument structure to enable a SAP.

The ioctl subroutine argument structure to enable a SAP (dlc_esap_arg) has the following specifics:

  • The grp_addr field is a 6-byte value as specified in the draft IEEE Standard 802.3 specifications. Octet grp_addr[0] specifies the most significant byte and octet grp_addr[5] specifies the least significant byte. Each octet of the address field is transmitted, least significant bit first. Group addresses sometimes are called multicast addresses.
    An example of a group address follows: 
    
0x0900_2B00_0004
    Note: The DLC8023 device manager does not check whether a received packet was accepted by the adapter due to a preset network address or group address.
  • The max_ls (maximum link station) field cannot exceed a value of 255.
  • The following common SAP flags are not supported:
    Item Description
    ENCD Indicates synchronous data link control (SDLC) serial encoding.
    NTWK Indicates a teleprocessing network type.
    LINK Indicates teleprocessing link type.
    PHYC Indicates a physical network call (teleprocessing).
    ANSW Indicates a teleprocessing autocall and autoanswer.
  • Group SAPs are not supported. Therefore the num_grp_saps (number of group SAPs) field must be set to 0.
  • The laddr_name (local address name) field and its associated length are used for name-discovery when the common SAP flag ADDR is set to 0. When resolve procedures are used (that is, the ADDR flag is set to 1), the DLC8023 device manager obtains the local network address from the device handler and not from the dlc_esap_arg structure.
  • The local_sap (local service access point) field can be set to any value except null SAP (0x00) or the name-discovery SAP (0xFC). Also, the low-order bit must be set to 0 (B`nnnnnnn0') to indicate an individual address.
  • No protocol-specific data area is required for the DLC8023 device manager to enable a SAP.