[HECnet] Thousands of DECnet errors on Tops-20

[Thomas DeBellis]

DDP?  I thought it was DUP-11.

> ------------------------------------------------------------------------
> On 1/15/21 4:21 PM, Peter Lothberg wrote:
>
> Well, MRC was receiving "suggestions" from Stu Grossman on how to do 
> it, but
> if my memory does not fail me the block size was 312, due to lack of 
> buffer space
> in the already crammed single section 512KW 2020. I'm afraid my tape 
> and disk-pack
> are in Seattle. I knew it was not 576 as it had two DUP-11's and using 
> it for transit failed...
>
> Quiz, do you knew what a DDP is?
>
> -P
>
> ------------------------------------------------------------------------
>
>     *From: *"tommytimesharing" <tommytimesharing at gmail.com>
>     *To: *"hecnet" <hecnet at Update.UU.SE>
>     *Sent: *Friday, January 15, 2021 3:59:25 PM
>     *Subject: *Re: [HECnet] Thousands of DECnet errors on Tops-20
>
>     Was this maybe that magical version 5 of Tops-20 that MRC put
>     together for the 2020?  I sure would love to see the sources for
>     that!  I'm not sure if this is relevant, but the following macro
>     in D36COM is of interest:
>
>         DEFINE KNMMCS,<
>         ;              Symbol,Name,Cost, Maximum receive block size
>                 KNMMAC LD.TST,TST,  1, 0                       ;TST DEVICE
>                 KNMMAC LD.DTE,DTE,  3, <^D576>                 ;DTE DEVICE
>                 KNMMAC LD.KDP,KDP,  4, <^D576>                 ;KDP DEVICE
>                 KNMMAC LD.DDP,DDP,  5, <^D576>                 ;DDP DEVICE
>                 KNMMAC LD.CIP,CI,   2, <^D576>                 ;CI DEVICE
>                 KNMMAC LD.NI ,NI,   1, <^D1504-%RTEHS>         ;NI DEVICE
>                 KNMMAC LD.DMR,DMR,  2, <^D576>                 ;DMR DEVICE
>         >;END OF KNMMCS
>
>     What can be seen is that the maximum block size is 576 in _all_
>     cases except the NI, which is 1476 bytes.  I don't know if any of
>     these devices are relevant to the 2020; one assumes that the DTE,
>     CI and NI are not.
>
>         ------------------------------------------------------------------------
>         On 1/12/21 3:29 PM, Peter Lothberg wrote:
>
>         The DECnet segment size has to be the same "network wide".
>
>         If I remember right DECnet looks at the two end nodes and uses
>         the smalles segment size,
>         so if there is any transit node in the path with a small
>         segment size things will not work as
>         it will drop packets bigger than it''s size.
>
>         The only SW/HW combination I knew of that has other than 576
>         is MRC/Stu DECnet for
>         Tops20 4.x on DEC2020.
>
>         -P
>
>
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