[Simh] Cluster communications errors

[Warren Young]

On Wed, Jul 18, 2018 at 12:21 PM Mark Pizzolato <Mark at infocomm.com> wrote:

>
>
> The simh Ethernet layer has dramatically more internal packet buffering
> (maybe 50 X) than anything real DEC hardware ever had.  This might account
> for the relatively smooth behavior I’m seeing.
>

More buffering can also mean more delay in the feedback loop that controls
the underlying protocols, leading to *worse* performance as buffer space
goes up.

This is called Buffer Bloat in the TCP sphere:

    https://www.bufferbloat.net/

Perhaps the low-level protocols involved in VAX clustering have the same
issue? They may be expecting to get some kind of feedback response, which
is getting delayed through the buffering, which causes the real VAXen to
kick the fake one out, thinking it's gone MIA.
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