The VERS9012 update to BITEARN NODES contains duplicate links for certain
nodes (all  of them from BITNET),  which could have resulted  in critical
operational  problems for  LISTSERV if  we had  not been  very lucky.  My
production server (1.6f)  detected an odd number of links  in the network
and refused to continue, under the  assumption that this meant you have a
node "hanging off the air" or  the like. After writing verification execs
and spending  1h trying to understand  what was wrong, I  discovered that
what we have is a number of duplicate links, as in ':adjnodes1.DUPR (...)
:adjnodes2.DUPR (...)'.
 
The net  effect on  release 1.6e  is that  no error  is detected  and the
server appears to work properly BUT:
 
1. Any LINKSWT FILE override for the  weight of a duplicated link will be
   ignored if the new weight is higher  than the normal one (which is the
   case most  of the time); this  is because only the  first occurence of
   the link will  be altered. Luckily, none of the  affected links had an
   override  in LINKSWT  FILE; I  will let  you imagine  what would  have
   happened if  transcontinental links  had failed  to have  been weighed
   properly and  EARN traffic  had been  routed through  the US,  or vice
   versa.
 
2. The  server will suffer from  a degradation in performance  due to the
   larger amount  of possible paths to  explore (all leading to  the same
   result).
 
3. I cannot guarantee  that there will be no other  problem, the code was
   simply not designed to handle multiple definitions of the same link.
 
LISTSERV@CEARN  crashed with  no message  whatsoever in  the console  log
during  the  tables  generation  procedure. It  subsequently  started  up
successfully after having been rebooted, but took an inordinate amount of
time (about  10 times longer  than normally) to  come up. Whether  or not
this means that the errors in VERS9012 cause 1.5o to crash is uncertain.
 
In  any case,  ALL  LISTSERV  sites may  want  to  monitor their  servers
carefully until the problem is corrected.  Here is a list of the affected
links:
 
-------------------------------------------------------------------------
3231 nodes in file.
Duplicate link: BYUVAX1  -> BYUVM
Duplicate link: CUCSC    -> CUHKVM
Duplicate link: DUVM     -> VILLVM
Duplicate link: DUVM     -> SWATPRM
Duplicate link: DUVM     -> DUPR
Duplicate link: DUVM     -> DUPHY1
Duplicate link: JNETC    -> JNETB
Duplicate link: NCSUMVS  -> NCSUVM
Duplicate link: NCSUVAX  -> NCSUIE
Duplicate link: NCSUVAX  -> NCSUECE
Duplicate link: NCSUVAX  -> NCSUCHE
Duplicate link: NCSUVAX  -> NCSUCE
Duplicate link: NER      -> FSUAVM
Duplicate link: PSUVM    -> BKNLVMS
Duplicate link: UICVM2   -> UIUCVMD
Duplicate link: UNTVAX   -> UNTVM1
Duplicate link: UNTVAX   -> NTSUVAXA
Duplicate link: UTARL    -> TAMNET
Duplicate link: UTHOU    -> UTMDAPH2
Duplicate link: UTHOU    -> UTMDAH
Duplicate link: UTORDOP  -> UTORUGW
Duplicate link: VCURUBY  -> URVAX
Duplicate link: WELLCO   -> WHEATNMA
Duplicate link: WISCPSLC -> WISCPSLB
Duplicate link: WISCPSLC -> WISCPSLA
Total: 25 duplicate links.
-------------------------------------------------------------------------
 
Two months  in a row,  now I'm getting  curious... What will  be UPDATE's
Christmas present to  the network? I think I'd better  not be around when
VERS9014 comes out.
 
  Eric
 
PS: I have moved  the LSTSRV-M list to SEARN so  that its subscribers can
    hope to receive this warning before the end of the month.