dna@dsd.UUCP (03/03/84)
TO: HM
FROM: PK
SENT: 29 FEB 84 06:45:07
READ: 29 FEB 84 20:02:19
After thinking about my poll/final addressing proposal some more and
talking to some others about it, I think it might be better to use the
high order bit (8) of the SSID bytes in the source and destination
address subfields for the command/response designation, rather than the
next-to-high order bit (7). Bit 8 is used for the H ("has been
repeated") indication in repeater addresses, but it currently serves no
function in the source and destination fields. Therefore, simply
substitute "bit 8" in place of "bit 7" in my proposal. Bits 6 and 7 of
all SSID bytes would remain reserved and set to one, thereby keeping open
the possibility of using these two bits to extend the SSID field at a
later time.
Compatibility with existing implementations of AX.25 should still be
maintained, as bit 8 of the SSID byte in source and destination addresses
is currently unused and set to zero. The test for whether the remote
station follows this new recommendation remains the same - nonequality
between the two bit 8's of the source and destination SSIDs. I *AM*
assuming, of course, that current implementations mask off the reserved
SSID bits and ignore them in address comparisons - I have no way to
verify this.
Phil