[HECnet] LQA system ID message

[Paul_Koning at Dell.com]

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.

	paul

On Feb 15, 2013, at 8:53 PM, Johnny Billquist wrote:

On 2013-01-24 20:29, Paul_Koning at Dell.com wrote:
I was watching the MOP Console system ID messages from DECnet/E on simh, with an emulated LQA.   Noticed something odd: the source address was broadcast.   That's not valid, of course.   The question is why that happened.

The answer is that the emulation uses the address in slot 0 of the address filter as the source address.   The hardware doesn't care what order the addresses go in as far as filtering is concerned; DECnet/E puts broadcast in slot 0 and the physical address in slot 1, followed by any multicast addresses.

Is the SIMH behavior also what a real LQA does?   That would be an interesting DECnet/E bug if so...   Or does a real LQA just use the physical address, as a UNA would?

Hi, Paul. Sorry for not responding sooner. Busy, as usual. However, I did mark this for some later investigation. However, I now realize that it's not trivial for me to test, as it would appear a RSTS/E system would help. :-)
I honestly don't know how a real LQA do. Maybe John Wilson knows more, since he have been digging into these kind of questions way more than most people I know...

Or else if you have some realistic suggestion on how I would test this on my machine, as I do have a 11/93 with a real LQA here (although an LQA plus).

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
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