2 Mar
2026
2 Mar
'26
6:42 p.m.
On Mar 2, 2026, at 11:44 AM, Johnny Billquist
<bqt(a)softjar.se> wrote:
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
Well, Multinet is not DDCMP, it isn't even in the same province. PyDECnet certainly
supports that, and when used over TCP should work ok in spite of its fundamental design
errors.
DECnet packet sizes are controlled by the executor parameters, in particular the segment
buffer size you mentioned. Yes, Ethernet supports bigger frames, but 576 was the
conventional max size used with DECnet. Actually, DDCMP also supports much bigger frames
(up to 16k is the max the protocol can handle) but that certainly isn't normally done,
especially not on PDP-11s for obvious reasons...
paul