In the SANA-II standard, network hardware addresses are stored in an array of n bytes. No meaning is ascribed by the standard to the contents of the array. In case there exists a network which does not have an address field consisting of a number of bits not divisible by eight, add pad bits at the end of the bit stream. For example, if an address is ten bits long it will be stored like this: 98765432 10PPPPPP BYTE 0 BYTE 1 Where the numerals are bit numbers and 'P' is a pad (ignored) bit. Driver users which do not implement the bit shifting necessary to use a network with such addressing (if one exists) should at least check the number of significant bits in the address field (returned from the device's S2_DEVICEQUERY function) to make sure that it is evenly divisible by eight. Driver users will map hardware addresses to protocol addresses in a protocol and hardware dependent manner, as described by the relevant standards (i.e., RFC 826 for TCP/IP over Ethernet, RFC 1201 or 1051 for TCP/IP over ARCNET). Some protocols will always use the same mapping on all hardware, but other protocols will have particular address mapping schemes for some particular hardware and a reasonable default for other (unknown) hardware. Some SANA-II devices will have "hardware addresses" which aren't really hardware addresses. As an example, consider PPP (Point-to-Point Protocol). PPP is a standard for transmitting IP packets over a serial line. It uses IP addresses negotiated during the establishment of a connection. In a SANA-II driver implementation of PPP, the driver would negotiate the address at S2_CONFIGINTERFACE. Thus, the address in SrcAddr returned by the device on an S2_CONFIGINTERFACE (or in a subsequent S2_GETSTATIONADDRESS) will be a protocol address, not a true hardware address. Note: ----- Some hardware always uses a ROM hardware address. Other hardware which has a ROM address or is configurable with DIP switches may be overridden by software. Some hardware always dynamically allocates a new hardware address at initialization. See "Configuration" for details on how this is handled by driver writers and by driver users.
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