Logical Boards

Board instances are not usable in and of themselves; they must first be associated with one or more frame types. Each {board instance, frame type} pairing is known as a logical board. Sending and receiving data on the network is always done in the context of a specific logical board. Logical board numbers are assigned based on the order in which the network software encounters their definitions.

For example, if a machine had an NE2000 Ethernet board installed, a driver (NE2000.COM) would be loaded for that board to create “NE2000 board instance #1”. If the driver was then configured to support both Ethernet_802.3 and Ethernet_II frame types, the first pairing, {NE2000 #1, Ethernet_802.3} would be known as “logical board 1”. The second pairing, {NE2000 #1, Ethernet_II) would be known as “logical board 2”.

Unlike board instance numbering, which is relative for each type of board, the numbering of logical boards encompasses all {board instance, frame type} pairings in the system. Therefore, adding to the previous example, if there was a token-ring adapter also installed in the machine, it would have a driver (TOKEN.COM) loaded to create “TOKEN board instance #1”. Assuming the driver was configured to support the Token-Ring_SNAP frame type, then the pairing, {TOKEN #1, Token-Ring_SNAP}, would be known as “logical board 3”. In summary, then, the logical board assignments from this example would be:

{NE2000 #1, Ethernet_802.3} logical board 1
{NE2000 #1, Ethernet_II} logical board 2
{TOKEN #1, Token-Ring_SNAP} logical board 3

Note that the actual load-order of the network drivers determines the logical board number assignments. If, changing the previous example, the TOKEN.COM driver was loaded first, then the logical board assignments would be:

{TOKEN #1, Token-Ring_SNAP} logical board 1
{NE2000 #1, Ethernet_802.3} logical board 2
{NE2000 #1, Ethernet_II} logical board 3