[HECnet] SETNOD, Part 2

[Johnny Billquist]

If there is some additional commands you'd like for me to put into 
FIX.T20, let me know.

The VMS commandfile I creates starts like this:

$ MCR NCP
PURGE NODE * NAME
CLEAR NODE * NAME
def nod 41.28 name 28NH
.
.
.

Which means that any previous definitions are first cleared out before 
any definitions go in.
This is because VMS (and RSX) do not handle if you have a node name that 
gets a different address. Clearing things out first solves that.

The alternate thing that can be done in VMS is that you can copy 
nodenames from within NCP from another node, which seems to avoid the 
problem as well (I think).

In RSX, the permanent nodename database in RSX can be created by a 
separate tool that does not at all relates to the current nodename 
database, so in RSX it's rather easy. You download a new database, and 
then you switch it over to the new db.

With other systems I don't know at all.

   Johnny


On 2021-05-31 20:50, Thomas DeBellis wrote:
> I was wondering if anybody would care to explain how routine node 
> maintenance happens for DECnet on non-Tops-20 systems. Specifically, 
> Johnny's node list on MIM:: changes more or less about once a month, 
> sometimes more, sometimes less.
> 
> Is anybody keeping up on this?  How?  I had a (bi-weekly) re-occurring 
> batch job which NFT'ed the latest node file from MIM:: and simply used 
> SETNOD to shove the whole thing into the running monitor, on the 
> assumption that the monitor would figure out what to do.  While slapping 
> in the whole list (with .NDINT) during timesharing did strike me as 
> somewhat wasteful, I didn't pay much attention to the matter as it did work.
> 
> This is mistaken.  Tops-20 will not 'make it' work, nor does it 
> apparently detect certain situations which appear to be problematic.  It 
> does detect and reject two situations.
> 
>  1. You may not change either the name or address of the host (I.E., the
>     Executor).  These can only be set once at boot up. Do other
>     operating systems have this restriction?
>  2. You may not change the address of an existing node in the local area.
> 
> A node insertion in the local area which usurps an address of another 
> node deletes that node.  Outside of the local area, you are on your 
> own.  It does whatever you want, which means that you can have multiple 
> nodes with the same address.  Is that a problem?  On IP4, this would 
> been known as 'aliasing', but I don't think DECnet allows this.
> 
> So it would appear that the appropriate behavior is that a new node list 
> implies a system reboot.  Unless I'm actively doing monitor development, 
> I can't stand doing this.
> 
> However, fixing the problem turned out to be pernicious.  Neither of the 
> two cases above is reported to the user program; there is no way to 
> determine what might have gone wrong.  There is no way for the user 
> program to proactively prevent errors because, while you can ask Tops-20 
> to translate a DECnet address to a node name and to verify that a DECnet 
> node name exists, there is no way to return the address for a verified 
> DECnet node name.  Is this an oversight?  Can a user program get the 
> address of a DECnet node name on other operating systems?
> 
> I remediated the low level error reporting issue and implemented a new 
> function for NODE% to return the address of an existing DECnet node 
> (.NDVFX or Verify Node Extended).  Fixing SETNOD proved impossible.  I 
> discovered that the actions to be performed were complex enough when 
> automated that the dimensions of the solution were wholly beyond its 
> capabilities.  Not that there was anything wrong with SETNOD, it just 
> wasn't designed for this kind of heavy lift.  So I rewrote it from 
> scratch (cleverly naming it SETND2). I'm converging on completion, but I 
> don't work on it actively, so this will probably be a few more weeks.
> 
> Here is some sample output; let's suppose that BOINGO needs its address 
> changed from 2.399 to 2.400 and that this conflicts with another node 
> (in this case, APOLLO). To get this to work right, what you need to do 
> is tell Tops-20 to do is delete BOINGO first, so that there is no name 
> clash on the insertion.  Then you have to delete APOLLO, so that there 
> is no address conflict.  Once you are done performing both these 
> actions, it's safe to do the insertion and Tops-20 doesn't reject it or 
> otherwise get itself confused.
> 
> @*setnd2*
> % Insufficient capabilities for INSERT command
> 
> SETNODE>*vERBOSITY* (level is) *vERBOSE *
> Verbosity level is VERBOSE
> SETNODE>*get /sECTION-MAP /nO-ACCESS*
> [BIN file: TOMMYT:<SYSTEM>NODE-DATA.BIN.91;RESTRICTED-JFN:13 ]
> Mapped one section (4 pages), 1778 Words, 889 Nodes.
> SETNODE>*recONSTRUCT /sILENT *
> [Closed log file: NUL:]
> SETNODE>*shoW aREA 2 uNCHANGED*
> [Area 2]
> A2RTR   ADAGIO  ADVENT  ADVNT5  AMAPUR  APOLLO  AUG11 AUGVAX  BASSET  
> BEAGLE  BELLS   BOINGO  BOXER   BULDOG  CHARON
> CODA    COLLIE  CONDOR  CORGI   COYOTE  CYPHER  DALMTN DIVISI  DOGPAK  
> ELIDYR  ELITE   FOX     GLDRTR  GLOVER  GRUNT
> HERMES  HUIA    HUNTER  HUSKY   JACKAL  JENSEN  KELPIE LABRDR  LAPDOG  
> LARGO   LEGATO  LENTO   MASTIF  MENTOR  MEZZO
> MULTIA  MUTT    NO0K    ODST    OINGO   OSIRIS  PAVANE POCO    POODLE  
> PUG     PUGGLE  PUPPY   R2X899  REACH   SPARK
> TERIER  THEARK  TOMMYT  VENTI   WLFHND  WOLF    ZITI
> Total nodes in area 2: 67
> SETNODE>*shoW **uNCHANGED boiNGO*
> BOINGO:: (2.399)
> SETNODE>*set 2.400 boingo*
> Set existing node BOINGO:: (2.400)
> Node BOINGO:: (2.400)
> % Removing node BOINGO:: (2.399) from same list to insert in the delete list
> % Re-using key text for insertion in delete list, BOINGO (2.399)
> % Removing BOINGO::'s previous address (2.399)
> % Removing node APOLLO:: (2.400) from same list to insert in the delete list
> % Re-using key text for insertion in delete list, APOLLO (2.400)
> % Deleting APOLLO:: (2.400) to reassign its address to BOINGO::
> % Allowing update request for node BOINGO:: (2.400) because being 
> deleted as (2.399)
> % Removing node BOINGO:: (2.399) from unchanged list because its address 
> has changed to (2.400)
> % Re-using key text for insertion in update list, BOINGO (2.400)
> Node change request for BOINGO:: (2.400)
> SETNODE>
> 

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol