[Simh] Cluster communications errors

[Larry Baker]

> On 20 Jul 2018, at 6:06:31 PM, simh-request at trailing-edge.com wrote:
> 
> Message: 1
> Date: Fri, 20 Jul 2018 22:53:33 +0200
> From: Johnny Billquist <bqt at softjar.se <mailto:bqt at softjar.se>>
> To: simh at trailing-edge.com <mailto:simh at trailing-edge.com>
> Subject: Re: [Simh] Cluster communications errors
> Message-ID: <ee193165-438d-a2ac-f867-991ad44b8b0b at softjar.se <mailto:ee193165-438d-a2ac-f867-991ad44b8b0b at softjar.se>>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> On 2018-07-20 16:20, Mark Pizzolato wrote:
>> On Friday, July 20, 2018 at 6:05 AM, Hunter Goatley wrote:
>>> On 7/20/2018 7:58 AM, Paul Koning wrote:
>>>> Is that the Ethernet interface down/up that happens when DECnet sets the
>>>> MAC address?  I assume you don't have a card that supports multiple MAC
>>>> addresses.
>>> 
>>> It probably is. That makes total sense, and I should have realized that.
>> 
>> I'm quite sure that the MAC address change happens much earlier than
>> the DECnet startup when a VMS cluster is configured on the system.  As
>> soon as the booting system gets its SYSGEN parameters and knows its
>> SCSSYSTEMID it 1) has enough info to set the DECnet MAC address and
>> 2) is capable of engaging in cluster communications using this ID (and MAC).
> 
> Well, I can at least confirm on a real 8650, the network also briefly 
> goes down and up again when DECnet is started. If I remember it even 
> happens independent of if you have the machine in a cluster or not.

Yeah, when I read Mark's comments I was thinking DECnet would still do what DECnet always does, which is change the MAC address to match the DECnet node number.  There is no particular advantage in checking first whether that has already been done.  The SCSSYSTEMID has to match the DECnet node number is all.  Whether one or both actually set up the hardware MAC address is not specified, from what I recall.

> If someone is really interested I can boot the machine up to VMS and 
> capture the output. I can also do some other tests and checks if anyone 
> is interested.
> 
>   Johnny
> 
> -- 
> Johnny Billquist                  || "I'm on a bus
>                                   ||  on a psychedelic trip
> email: bqt at softjar.se <mailto:bqt at softjar.se>             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
> 

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov

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