16 Jul
2024
16 Jul
'24
3:20 a.m.
My question wasn't about the exact number, but the fact that it was not
the number shown by NCP.
There is control over both in RSX as well, but there NICE isn't
reporting the buffer size in that parameter, but you can see it in
another place, and yes, it's the value used in the routing advertising,
which makes sense, since that is what you announce you will accept as
size for routing packets. And yes, it's (completely) unrelated to the
segment buffer size, which is what NSP cares about. And as long as the
buffer size is atleast large enough to hold the maximum segment size,
everything will be happy.
I also haven't checked any code, but for ethernet, I would think that
routers will either send out 1500 byte packets, or send out the packet
the size of the smallest announced accepted size. Now I'm sortof curious
which. Maybe the DECnet routing spec already would tell me... I know
that for point-to-point links, RSX sends packets larger than the segment
size if routing init says it can accept that, as long as the sending
side can build that size.
And that is also where VMS had the bug that I mentioned before.
Johnny
On 2024-07-16 03:12, Thomas DeBellis wrote:
Yes, 1746 has always struck me as an odd number, but
the macro
definitions which calculate it were puzzling enough that I didn't want
to assume. As I recall, there was commentary about fidgeting withthe
number which I also didn't think I understood at the time. But this was
over three years ago, so I could certainly be misremembering.
Just as a reminder for any Tops-20 user: your ERROR.SYS file */will/*
fill up with class 5 events (buffer not large enough) if you don't
condition NTMAC to ignore this. At NMXFIL+1, you need to change three
lines, viz:
NMXFIL: $SFIL
$FIL(2,4) ;[T152] ;Event classes 2 through 4 known by monitor
$NOFIL(5,5) ;[T152] ;HECnet overflows us with packet too long
$FIL(6,6) ;[T152] ;Event class 6 known by monitor
$NOFIL(^D96,^D96) ;LCG specific events - turned off
IFN FTDEBUG <
$FIL(^D480,^D480) ;Accept event class 480 while debugging
$EFIL
On 7/15/24 9:04 PM, Paul Koning wrote:
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
I think that 1476 is a TOPS-20 private thing, the
data link buffer sized used by the Ethernet driver. The NCP parameters control what
routing advertises (buffer size) and what NSP asks for as connection segment size(segment
buffer size).
paul
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To unsubscribe send an email to hecnet-leave(a)lists.dfupdate.se On Jul 15, 2024, at 8:49 PM, Johnny
Billquist<bqt(a)softjar.se> wrote:
Maybe someone can explain to me why it looks like the buffer size reported by NCP is 576
when it sounds like you are both setting it to 1476?
Johnny
On 2024-07-15 22:48, Thomas DeBellis wrote:
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To unsubscribe send an email tohecnet-leave(a)lists.dfupdate.se 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 1476length 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 NTMANfor packets being too long.
------------------------------------------------------------------------
On 7/14/24 5:04 AM, Johnny Billquist wrote:
> Anders...
>
> On 2024-07-14 10:20, Anders Andersson wrote:
>> "merlyn drforbin"<kropotkin(a)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 theDECnet 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
>
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--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email:bqt@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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