HECnet

[Johnny Billquist]

"Robert Armstrong" <bob at jfcl.com> wrote:

>   I'm interested in setting up a network of hobbyist DEC machines linked
> together in a DECnet phase IV network.  Why?  I suppose there's no really
> good reason, but it seems like it would be fun to be able to do "SHOW NET"
> or "NCP SHOW ACTIVE NODES" and see a whole long list of machines that aren't
> mine :-)  Besides, it would be a good way to share access to real,
> non-simulated, VMS/RSX/RSTS and even, maybe, TOPS-10 or 20, machines.

And it's fun to interconnect different OSes and architectures.

Since this question now has popped up, I thought I'd go through a few 
points of interest for those who want to know or join.

First of all, yes, HECnet exists, works and have done so for a couple of 
years. But the interest have been very limited.
I don't know why. Maybe because I don't frequent the right group of 
people. Same reason people tend to forget the ftp archive I have of 
PDP-11 software, which (in my eyes) is the better place to find atleast 
RSX stuff. :-)

To begin with: HECnet is DECnet Phase IV, and nothing else.

Anyway. HECnet started out as point-to-point connections using asynch 
serial DDCMP. This was because it was the easiest and most obvious way 
to solve this. Tunneling normal serial interface traffic is very easy. 
It was, however, limited by both by which OSes actually supported this 
(RSX and VMS afaik), the fact that you needed physical asynch interface 
on the machine, and the fact that this limited the network speed to 9600 
bps.

The next step was to tunnel ethernet instead. I wrote a small program 
running under Unix which does exactly that. It uses the berkley packet 
filter to get packets, and to send them as well.

This means that an independent machine on the same ethernet segment is 
needed to do the tunneling. At the time I was doing this, I couldn't 
find any ready solution for this.
I did look at GRE, but figured it cannot be used, since it requires the 
OS to atleast understand the packet in order to figure out that it 
should go on the GRE tunnel. DECnet is not understood by most Unix 
versions. Now, if I'm wrong, I'm all ears to implementing it.
There also sometimes exist a bridge interface, which might be useful, 
but once again I haven't exactly been sure, so I've skipped it for now.

My current bridge program have some flaws that are related to DECnet. 
First of all it don't learn where different MAC addresses are, to limit 
transmits. Second, you can decide which machines packets that are sent 
out on a bridge, but since it appears as one single ethernet segment, 
things can get wrong when one machine in one area wants to talk with a 
machine in another area, and wants to use the other areas router 
directly (since they have contact). This means that if you run an area 
router, you actually need to allow all machines to send traffic to anywhere.

Some of these things are easy to improve, and I should probably address 
them. But since interest have been so low, the need hasn't exactly been 
acute. But maybe if this picks up.

If you want to join HECnet, there are a few things we need to fix. First 
of all, we need the connection established. My machines are sitting at a 
site where I have very large bw, and no problems running 24/7. I have an 
area router, and another machine that acts as the bridge. So what you 
need is a machine to act as your endpoint of that bridge. It can either 
be a Unix machine, or something else, if we just get the connection 
going to some other host on HECnet. The requirements for my bridge 
software is really a machine that can send ethernet packets with 
anything as the source mac address, since that need to be faked. Most 
modern PCs can fake that, but I don't think SUN machines can. If you'd 
prefer to run something else than Unix, I'd be happy to help porting my 
bridge program. If you have a machine that actually can route DECnet 
over IP, it's in a way a better solution, but I can't deal with it right 
now. We'll have to start working on it. Let me know and we can talk.

Second, since DECnet have addresses as well, this address database needs 
to be organized and allocated. For HECnet, I need to administer this. 
What I do is either allocate an area for someone who wants it, and then 
that area can be managed locally, or I can assign addresses from area 1, 
which I use myself.
At the moment, only areas 1 and 11 have been spoken for.
The node namespace in DECnet is flat, and while it's also local to every 
machine, it's nice to try to keep it uniform, so I prefer to keep track 
of node names, and have a master list locally, which people can copy 
from when they want to. That also means you should register wanted node 
names.

The area router for area 1 is an RSX-11M-PLUS machine. There are 
actually several area routers on area 1.
MAGICA:: is a real PDP-11/70 running RSX-11M-PLUS.
MIM:: is an emulated PDP-11, running RSX-11M-PLUS.
ERNIE:: is a real PDP-11/84 running RSX-11M-PLUS.
PONDUS:: is a real PDP-11/83 running RSX-11M-PLUS.

ERNIE and PONDUS are at my home, and since my ISP left me stranded I 
don't have any permanent connection to my home right now, so they are 
mostly offline.
MAGICA is normally not on at the moment, because of budget problems.
This leaves MIM. MIM is normally online and running. I have been 
experimenting (together with John Wilson, the author of E11) with MIM 
lately in some interesting new features, which unfortunately have left 
MIM without a working ethernet at times. However, if we're serious about 
this, I can always keep MIM running a bit more safe.

There are about 20 machines in area 1, and about the same number in area 
11, which is managed by Saku Setala in Finland.

The machine running the bridge is normally always on as well, so even 
with MIM out of the loop, everything should work fine.

If you have any questions, just write me.
If you want to join, write me as well. We'll start by figuring out how 
to hook you up, and we'll also allocate nodes, or an area for you.

	Johnny

> 
>   Does anyone else agree?  Is anyone else interested in participating?
> 
>   I know I'm not the first to think of this; in particular, I've had a few
> email discussions recently with Johnny Billquist about HECnet,
> 
> 	http://www.update.uu.se/~bqt/hecnet.html
> 
> At some point I'd like to link up with HECnet, but right now Johnny is
> having ISP problems and it sounds like HECnet is down to one or two nodes.
> 
>   Are there any other hobbyist DECnet associations that are going strong?
> 
>   As for technology, it seems like the best thing would be to use the
> Internet as our communications medium.  Nobody wants to pay for
> point-to-point leased lines anymore, after all.  Multinet, TCPware, and even
> DECNet Phase V all have the ability to send DECnet traffic over IP.  Right
> now I'm leaning towards Multinet - they have a free hobbyist license
> program, and Multinet can create point-to-point virtual DECnet circuits
> using UDP packets that can be routed over the Internet.  They're simple to
> set up and administer.
> 
>   I have a fair amount of Internet bandwidth available at my location, and I
> can set aside a VS4000 VLC or model 90 to serve as a dedicated Phase IV
> routing node.
> 
> Bob Armstrong
> 
> 
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Thu, 8 Dec 2005 23:43:29 GMT
> From: Pete Turnbull <pete at dunnington.plus.com>
> Subject: Re: Legacy apps in Windows/OS X was Re: Old MS-DOS & Win
> 	Software
> To: "General Discussion: On-Topic and Off-Topic
> 	Posts"<cctalk at classiccmp.org>
> Message-ID: <10512082343.ZM22810 at mindy.dunnington.plus.com>
> Content-Type: text/plain; charset=us-ascii
> 
> On Dec 8 2005, 16:26, Jim Leonard wrote:
> 
>>Allison wrote:
>>
>>>You lived a shelterd life.
>>
>>I lived a young life.  I first became of programming age in late
> 
> 1970s so my
> 
>>first CPUs were 6502, Z80, 68000, and 808x.
> 
> 
> Whether it's called a Half Carry or an Auxiliary Carry seems to depend
> somewhat on whose data book you read.  I've seen both used for the Z80
> for example, indifferent manuals.
> 
> ...in a 6800, it's called the Auxiliary Carry; in a 6809 it's called a
> Half Carry.  It's bit 5 of the status register in both.
> 
> ...in a Z80 and 8086 it's called the Auxiliary Carry; it's bit 4 in the
> Flags register in these and 8080/8085.
> 
> ...it's bit 5 in 8048 and 8051 series micrcontrollers.
> 
> There's no (visible) equivalent in a 6502 because of the way its
> special Decimal Mode for BCD arithmetic works.  Ditto for a 68000.
>  There isn't one in an ARM either.
> 

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol