[Simh] DECnet problem with SIMH PDP11 vs real PDP11

[Broer van Smeden]

Dear Göran and all,

Some years ago, we face a similar problem on our site. We have 2 AXP sytems,
both with 4 ethernet adapters. We planned to run DECNET en normal IP traffic
for one (to our site lan) and two other were connected to 2 separated (IP)
lan's. Because one system was a kind of backup to the other 'production'
system, also the backup system was coonected to the special (IP) lans. All
DECNET copies to other nodes were OK, but between the both systems, all was
very slow (even slower than PDP and VAX).
So you migth try to prevent a 'double path' by just disconnecting some
(coax?) wiring.
Furthermore, I remember from the past that the blocksize between PDP-11 and
VAX/AXP might also influence, but I'm not familiar with the setting of
DECNET and setting up decnet area's and routers. So also in that area, a
problem can be present.

Kind regards 
Broer van Smeden

-----Oorspronkelijk bericht-----
Van: simh-bounces at trailing-edge.com [mailto:simh-bounces at trailing-edge.com]
Namens Göran Åhling
Verzonden: Sunday 30 March 2008 10:02
Aan: simh at trailing-edge.com
Onderwerp: [Simh] DECnet problem with SIMH PDP11 vs real PDP11

Hi all,
DECnet copy from RSX11M-Plus on a SIMH-PDP11 is darn slow  to a real 
PDP11, but ok to a VAX/VMS...

Can anyone give a clue where I should search this problem (Is it DECnet 
routing? Is it SIMH? Is it WinPcap? ...)
Players in this drama are: P1, P2, S and V  (real PDP11-93 #1 and #2, 
SIMH-PDP11-93 and real VAX 4000)
S is an exact clone (copy) of P1, in every part but the DECnet name and 
address. The scene is a common ethernet (switched, some cisco switches 
with fibres inbetween take care of this... There could be a cisco router 
in it aswell, I don't have control of this part)
A DECnet copy, or an equal NFT, from P1 to P2 works with speed as 
expected on a common ethernet, but the same copy from S to P2 takes time 
like eternity (a .TSK file of some 10 kb's takes like 10 minutes). To 
check things out, i was logged into V, and made a identical copy of the 
identical file, from S to V, while S was doing a 10 min. copy to P2. 
this S to V copy was finished within seconds...

Might it be a clue that I can't initiate any copy to V from any PDP 
(real or simulated), as I get "remote FAL not ...", but the same 
transfer initiated the other way workes fine. (I have guessed this is a 
separate problem I'll addres later, but I can be misstaken here...)

Details:
All these PDP11 systems are 11/93 running RSX11M-PLUS 4.6 bl 87. The VAX 
is running VMS v 7.1 Ethernet interfaces in the PDP:s are DELQUA or 
DELQUA+ (I haven't checked which one) - the VAX is using the 
"mother-board" interface.
All machines run DECnet phase IV, as "original" (read: oldish...) DEC 
supply. The name and addresses of the simulated PDP is entered into the 
table of these machines, but not into all machines on the network. All 
these machines are within the same DECnet area.
The network uses a few cisco swithches, but is not mixed with any TCP/IP 
or other traffic. (The machines are located in different buildings...)

The SIMH is v 3.7-3, WinPcap 4.0.2, Win XP fully "updated", the system 
also has a Symantec antivirus program installed, (but I think it should 
not interactat at all in this, and espetially not more in S to P1 than 
in S to V). HW is some DELL pc, with an extra netw. card in the PCI-bus. 
"Regular" PC netwroking (TCP/IP) is run on the mother-board ethernet, 
the extra plugged in adapter is "enabled" in windows set-up, but all 
protocols etc that can be selected to use this port are "un-hatched", 
thus not one single item in the network setup "this connection uses the 
following items" is active towards it. The SIMH PDP is attached to this 
network adapter that is connected to the DECnet. None of the PDPs or the 
SIMH has any TCP/IP onboard.

Any clue where to start looking for the problems, or any other 
suggestion to address this problem of mine, is appreciated,
/Göran
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