These are the relevant lines from my SYSTEM:7-1-CONFIG.CMD:

DECNET BUFFER-SIZE 1476
DECNET MAXIMUM-ADDRESS 1023
NODE VENTI2 2.522
DECNET ROUTER-LEVEL-1
ETHERNET 0 DECNET

The maximum buffer size of 1476 is what I determined from a review of the relevant code in the monitor, which I commented about, some months back (but see below).

This is the response from my local excutor (VENTI2::)

OPR>ncp shOW exECUTOR chaRACTERISTICS

Request # 280; Show Executor Node Characteristics Completed

Executor Node = 2.522 (VENTI2)

  Identification = Venti Due Test System
  Management Version = 4.0.0
  CPU = DECSYSTEM1020
  Software Identification = Tops-20 7.1 PANDA II
  Loop Count = 1
  Loop Length = 127
  Loop With = Mixed
  Incoming Timer = 30
  Outgoing Timer = 60
  NSP Version = 4.0.0
  Maximum Links = 65535
  Delay Factor = 48
  Delay Weight = 10
  Inactivity Timer = 120
  Retransmit Factor = 10
  Routing Version = 2.0.0
  Type = Routing IV
  Routing Timer = 600
  Broadcast Routing Timer = 40
  Maximum Address = 1023
  Maximum Circuits = 20
  Maximum Cost = 100
  Maximum Hops = 16
  Maximum Visits = 20
  Maximum Broadcast Nonrouters = 64
  Maximum Broadcast Routers = 32
  Maximum Buffers = 80
  Buffer Size = 576
  Segment Buffer Size = 576

The buffer size of 576 is what I remember being for non-Ethernet packets going over an IMP (which I'm sure is irrelevant because this was IP only).  1500 is the maximum for non-jumbo sized Ethernet frames, the 1476 length being 24 bytes less.  I plan to investigate that when I finally get into the guts of why ERROR.SYS fills up with class 5 errors from NTMAN for packets being too long.

Anders...

On 2024-07-14 10:20, Anders Andersson wrote:

"merlyn drforbin" <kropotkin@gmx.com> wrote:

Any way to set endpoint buffer size on panda decnet phase IV

Could  some of this  (in SYSTEM:7-CONFIG.CMD) be what you are looking for?
This is from RARITY (not PANDA, but DEC vanilla distribution,kind of), I'm
not sure I have  the correct values myself, been  experimenting.
         ; DECnet parameters:
;default is DECNET BUFFER-SIZE 576
decnet buffer-size 1476
;default is DECNET MAXIMUM-BUFFERS 80
;decnet maximum-buffers 40

Hmm. That do not seem to be the values currently used:

.ncp tell rarity sho exec cha

Node characteristics as of 14-JUL-24 10:58:22

Executor node = 1.802 (RARITY)

   Identification = Rarity of Maneframe Six
   Management version = 4.0.0
   Software identification = DECnet-20 Version 4.0
   Loop count = 1, Loop length = 127
   Loop with = Mixed
   Incoming timer = 30, Outgoing timer = 60
   NSP version = 4.0.0
   Maximum links = 65535, Delay factor = 48
   Delay weight = 10, Inactivity timer = 120
   Retransmit factor = 10, Routing version = 2.0.0
   Type = Routing IV, Routing timer = 600
   Broadcast routing timer = 40
   Maximum address = 1023, Maximum circuits = 20
   Maximum cost = 100, Maximum hops = 16
   Maximum visits = 20, Maximum broadcast endnodes = 64
   Maximum broadcast routers = 32, Maximum buffers = 80
   Buffer size = 576, Segment buffer size = 576

.


However, also to clarify some things. The segment buffer size should probably stay at 576. This is basically the size of packets used at the DECnet level, and I have some vague recollection that nodes should use the same size, or DECnet might fail. DECnet is not that clever about different sizes there.
The buffer size on the other hand can be larger (modulo VMS bug that I mentioned a few days ago), but that would only be used by link layer protocols, like the routing information packets that are sent, for example.

But if you are experimenting, please let me know if you figure something out. Positive or negative. Always good with more information.

  Johnny