[HECnet] LQA system ID message

[Johnny Billquist]

On 2013-02-16 22:59, Johnny Billquist wrote:
On 2013-02-16 22:45, Paul_Koning at Dell.com wrote:

On Feb 15, 2013, at 9:24 PM, Johnny Billquist wrote:

On 2013-02-16 03:03, Paul_Koning at Dell.com wrote:
The thing to do would be to see what happens if you load some
multicast address (such as broadcast) into slot 0 of the 16-entry
address match table, and the station address into slot 1.   For a
QNA, that's perfectly fine because all slots are equivalent and the
device doesn't do any MOP.   It may be that this was a later
restriction that RSTS didn't obey.   Or it may be a bad assumption in
the real LQA that wasn't documented -- or maybe it's just a bad
assumption in the SIMH emulation.   I haven't yet looked for LQA
manuals to give more clues.

Ah. I thought you had already checked documentation.

Well, I did now, and simh is right. Page 3-31 of the DELQA manual
states that the first address is used as the source address for
system ID messages.

Which edition?   I'm looking at EK-DELQA-UG-002 (from Bitsavers) and it
can't find anything like that.

The very same.
Page 3-31, Section 3.6.2.4, third paragraph:

"Any columns not used should be set to the physical address (for better
protection against mischievous Ethernet traffic). More than one physical
address may be specified, but in Normal mode, only the first is used for
receiving datagrams, and as the source address for system ID messages
generated by the DELQA."

I just realized that I might be reading that a bit too strict. "First physical address" could be read as the DELQA scans through the table and takes the first physical address it finds, if the implication is that multicast addresses are not physical addresses.
I have not verified this, but it do seem unlikely that the controller would scan through that table or do any more advanced operations on it ever. But I guess there is some room for interpretation here...

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol