> I haven't tried examining the traffic with tcpdump but I netboot a 
> DEC 3000 - M400 using

> >>>  boot ez0

> as per the user guide.

e*z*?  I'll have to try that.  I found a PDF (I loathe PDFs; give me
good old plain text any day) that appeared to say ex0.  But trying to
boot from ex0 failed, and trying to boot from kw0 (which I invented on
the spot) failed in the same way, so I assumed it was just a question
of what kind of Ethernet was in the machine.  But the PDF's resolution
on the screen was quite poor, so it could well have said ez0 instead.

> It's  show dev  also calls the 10baseT interface ESA0, so perhaps
> this will work for your 400S too.

Turns out it does.  Apparently booting from esa0 uses MOP and ez0 uses
tftp/bootp.

> I didn't attempt a netboot before upgrading to the latest firmware,
> which might be important.  If you want/need to upgrade, beware that
> it's vitally important to have an SROM with the correct version,

Yes, I'd noticed that.  But if I'm raeding SHOW CONFIG output
correctly, I already have the latest version:

>>> show config

DEC 3000 - M400
Digital Equipment Corporation
     VPP PAL V5.56-82000101/OSF PAL V1.45-82000201 - Built on 27-JAN-1997 19:34:48.30

TCINFO      DEVNAM        DEVSTAT
------      --------      --------
                 CPU      OK KN15-BA -V7.0-S887-I21F-sV1.0-DECchip 21064  P3.0

So I don't think I'll bother even thinking about firmware upgrades
unless I can find something newer than 7.0, which seems to be the
latest on ftp.digital.com.

> I guess you've also noticed it's necessary to have the  vm=rfc1048
> option in /etc/bootptab for these machines?

I saw it documented.  Until I tried ez0 just now, though, I'd never
gotten to the point where bootp even mattered, so I hadn't paid too
much attention to the details.  Now that I see tcpdump reporting bootp
queries and tftp attempts, I feel confident I can get it the rest of
the way home.

Thank you very much for that pointer!

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