[HECnet] DECnet-10 doesn't work past Nov 9 2021?

From: "John Forecast" <john at forecast.name> To: "hecnet" <hecnet at Update.UU.SE> Sent: Sunday, December 27, 2020 12:30:54 PM Subject: Re: [HECnet] DECnet-10 doesn't work past Nov 9 2021?

> On Dec 27, 2020, at 11:46 AM, Robert Armstrong < [ mailto:bob at jfcl.com | > bob at jfcl.com ] > wrote:

> This topic came up on the alt.sys.pdp10 list > [ https://groups.google.com/g/alt.sys.pdp10/c/ZttQxHZGEJQ | > https://groups.google.com/g/alt.sys.pdp10/c/ZttQxHZGEJQ ] > Apparently DECnet-10 won?t work past November 9 th 2021, which isn?t that far > away. Personally I?d never heard this before and had no idea, and since I know > there are a few 36 bit emulations on HECnet that are obviously using DECnet I > thought I?d pass it along. > TOPS20 isn?t explicitly mentioned, but I?m guessing that it has the exact same > issue. That?d mean no DECnet on 36 bit systems after next year! Unless, of > course, you want to start playing games with the date (which I hate doing)? > Bob

It?s not just a DECnet-10/20 problem. DECnet event logging for any system may fail after Nov 9th 2021. Events are time-stamped when they are generated with a 2-byte field holding the number of half julian days since Jan-1 1977. The spec (Network Management 4.0.0, page 170/171) implies that these 2 bytes should be treated as a signed value (0 - 32767) which will overflow on Nov 9th 2021. If the code treats it as unsigned, then we?re good for another 44 years. I wrote most of the RSX and Ultrix event logging code but I don?t remember if that field was treated as signed or unsigned. Phase V fixed the problem allowing the time stamp to go well past the year 9999.

John.