2 Mar
2026
2 Mar
'26
6:57 p.m.
On 02/03/2026 18.50, Paul Koning wrote:
Agreed. Multinet and UDP is a bad match. It usually works, but it's far
from ideal. TCP makes much more sense.
And RSX only speaks Multinet. DDCMP without the Multinet headers are not
dealt with. I guess it would be possible to add, but then I'd have to
process and understand when one frame ends, so I can give it to DECnet
properly.
On Mar 2, 2026, at 12:46 PM, John H. Reinhardt
<johnhreinhardt(a)thereinhardts.org> wrote:
On 3/2/2026 10:44 AM, Johnny Billquist wrote:
PyDECnet is basically omnilingual. So you need to find out what line protocol the other
end uses and then configure PyDECnet to match. If theother side runs Multinet, you'd
configure that (making sure to set the directions correctly: one is originating, the other
incoming). And don't use Multinet over UDP unless nothing else is available, because
it is an utter crock. Hm. The command "MNC SET CIR IP-0-5 MODE
DDCMP" should have given a warning that this has been deprecated. In essence, it does
nothing.
All links are just multinet links, which is DDCMP, with a small header to just get whole
packets when using TCP.
Johnny
That explains the "MLTNET" in Marks error log. So, if I set up the phDECnet
circuit as a Multinet one is should work?
On 02/03/2026 17.38, Johnny Billquist wrote:
> I don't think I've ever tried that DDCMP mode. I don't even rememberwhat
it does...
>
> Why are you wanting to use it?
>
> Johnny
>
Because that's what I was told needed to be done to connect to other HECnet nodes?
Mark has several set up that way and so does Supratim. I generallly suggest DDCMP because it works well, but
lots of other options have been used. Some of my preference comes from history; for
example I tend not to use Ethernet (or GRE, basicallly the same thing) for "wide
area" use because it's a LAN and back when it wouldn't work for WANs.
Nowadays the Internet is so fast that it's a reasonable option in many cases (though I
would still hesitate to run it on a trans-Atlantic circuit).
It works to the other side of the world just fine. However, the problem
if you play ethernet is that you're doing my bridge, and that have
scaling issues, since on ethernet everyone is supposed to be able to
directly talk to everyone, but also multicasts should go everywhere.
Which becomes ugly if the ethernet is tunneled to many places but still
appears as one segment.
GRE can get into the same pickle. While individual GRE links are also
point-to-point, there is no stopping you from having multiple ones of
them...
Johnny