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Method and Apparatus for Obtaining, in Multiple Formats, a Network Address Stored in a Single Format

IP.com Disclosure Number: IPCOM000123878D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Branstad, MW: AUTHOR [+3]

Abstract

Network interface cards (NICs) generally have a 12 hexadecimal digit media access control (MAC) address stored on them that is unique to each individual card. Depending on the protocol/software being used with the NIC, the preferred format of the MAC address is different.

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This is the abbreviated version, containing approximately 81% of the total text.

Method and Apparatus for Obtaining, in Multiple Formats, a Network
Address Stored in a Single Format

   Network interface cards (NICs) generally have a 12
hexadecimal digit media access control (MAC) address stored on them
that is unique to each individual card.  Depending on the
protocol/software being used with the NIC, the preferred format of
the MAC address is different.

   In non-canonical format, the MAC address is viewed exactly
as the 12 hexadecimal digit value it is.  For example
X'0123456789AB'.  In canonical format, the MAC address is viewed as
the digits would be sent on the transmission medium, i.e. the bits of
each hex digit are reversed.  The canonical format of the previous
X'012 3456789AB' would be X'084C2A6E195D'.  Each hex digit's bit
ordering is reversed.  Hex X'1' (binary 0001) becomes X'8' (binary
1000), hex X'5' (binary 0101) becomes X'A' (binary 1010), etc.

   Storing both versions of the MAC address in any
non-volatile storage that is pressed for space can be difficult.  It
is also a minor nuisance for any software that uses one format of the
address if the address is stored in the other format.  A conversion
from one format to another would be required.

   A communications adapter chip with the capability of
reading data (including the MAC address) from onboard nonvolatile
storage has been designed such that the MAC address is read from the
nonvolatile storage and stored in a register on the chip.  The
register itself has 2 accessib...