2.2.9 DN_ALTERNATE_ADDRESS (IPv4)
In DirectPlay 9, the DN_ALTERNATE_ADDRESS structure provides additional options for Internet Protocol (IP) connectivity. The alternative addresses included in DN_ALTERNATE_ADDRESS are supplemental to the primary address specified in the DN_ADDRESSING_URL structure.
In the DN_ALTERNATE_ADDRESS structure, the wPort field is derived from its conversion into a 2-byte binary value, and the dwAddrIn field is derived from its conversion into a 4-byte binary value. Both of these fields are treated as single binary buffers, and therefore, are not handled in network byte order. For example, a port value of 2302 would be converted into its 2-byte binary value of 00001000 11111110, and an IPv4 transport address of 65.52.239.061 would be converted into its 4-byte binary IN_ADDR value of 01000001 00110100 11101111 00111101.
The DN_ALTERNATE_ADDRESS (IPv6) (section 2.2.10) structure demonstrates the contents of the same structure when it contains an IPv6 alternative address.
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bSize |
bFamily |
wPort |
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bSize (1 byte): The size of this DN_ALTERNATE_ADDRESS (IPv4) structure excluding the size of this bSize field.
bFamily (1 byte): The address family for this DN_ALTERNATE_ADDRESS (IPv4) structure, which MUST be set to 0x02.
wPort (2 bytes): The port value for this DN_ALTERNATE_ADDRESS (IPv4) structure. This field is treated as a single buffer and is not specified in network byte order.
dwAddrIn (4 bytes): The address of the corresponding IN_ADDR (IPv4) structure for this DN_ALTERNATE_ADDRESS (IPv4) structure, as described in [MS-DPDX] section 2.2.35.1. This field is treated as a single buffer and is not specified in network byte order.