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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

557.0. "Unseen LAT services" by LARVAE::HARVEY (Baldly going into the unknown...) Tue May 05 1992 09:59

    
      Further to the previous note from Adrian Leate and DECnet "funnies", we 
      are seeing some strange LAT (and possibly similar DECnet) behaviour in 
      our second MDF installation too.
    
      We are running LAT over the ethernet controllers of FDDI connected nodes.
      A DECbridge 510 in each lobe connects the ethernet to the FDDI. 
      There are no bridge filters installed.
    
      Symptoms:
      A terminal server on the same ethernet segment can see/offer ALL LAT 
      services from nodes on that segment - including the FDDI connected (MDF) 
      nodes.
    
      A remote lobe terminal server (connecting over the FDDI backbone via 
      DECbridge 510) can see/offer LAT services of all the ethernet connected 
      nodes but cannot see/offer the LAT services of the FDDI connected nodes.
    
      This situation works the same for terminal servers on each lobe's 
      ethernet segments   ie. it's consistent at least !
    
      Anyone have any ideas ? We are chasing up the startup sequence of LAT at 
      the moment as it appears there are problems if you start it over one 
      circuit, stop it and restart over another circuit   ie. stop LAT over 
      FDDI and restart over ethernet etc. This may be the culprit in our 
      current configuration.
    
      Thanks in advance
    
      Rog
T.RTitleUserPersonal
Name		DateLines
557.1Further update/progressLARVAE::HARVEYBaldly going into the unknown...Thu May 07 1992 11:4547
    
      Just to add some more info after more activity last night and today.....
    
      The scenario described in -1 was still there after we had checked the 
      startups for LAT, which was set to work over the ethernet only.
    
      After discussion with the customer he undertook to start LAT over the 
      FDDI links AS WELL as ethernet on the cluster nodes. This cured the 
      "unseen" LAT services problem as described previously, and remote 
      terminals could connect to all offered LAT services - quite essential for 
      correct cluster/network operations really !
    
      However, I was/am not altogether happy that this dual-circuit LAT 
      operation (on the same extended/bridged LAN) is supported and a "clean" 
      solution - I am attempting to check this out - and in due course today 
      the customer has since reset LAT to use only the FDDI links. 
    
      It appears that the cluster nodes' LAT services can be seen and used by 
      terminal servers - so far so good !
    
      I might add that DECnet is running over the FDDI only, the ethernet 
      circuit being switched off.
    
      Now another "funny" has occured with LAT - this time with PCs running 
      PCSA. (I may need to gather more info here, but this is the scenario as I 
      currently understand it from a phone call taken earlier...)
    
      A PC connects via Thinwire (behind a DESPR) to a cluster lobe's thickwire 
      segment.
    
      This system boots/loads PCSA and can see its server which resides on 
      another separate thinwire behind another repeater off the thick segment.
    
      Ethernet only nodes can be seen/connected to via DECnet SETHOST and LAT 
      Terminal Emulation software. However, the MDF Cluster nodes offering LAT 
      and DECnet via the FDDI links cannot be seen/conneted to, even though 
      there is the DECbridge 510 in place linking the ethernet segment to the 
      FDDI. Both LAT and DECnet don't work. Wierd !?
    
      Any takers for this set of "features" ?
    
      Hoping for a speedy response - my customer has been very patient so 
      far.....
    
      Thanks
    
      Rog
557.2A few SuggestionsSR71A::RLEBLANCRene' Marc LeBlanc DTN 297-6794Thu May 07 1992 13:1223
    
    
    	Simple Questions for Features...
    
       Have you checked to make sure that the nodes on the FDDI offering
      LAT services have the LAT$DEVICE or SET LINK command pointing to the
      right hardware controller? do a SHOW DEV xxx /Full (xxx = mnemonic
      FDDI device) and see if there is a LATCP process associated with it.
     
      As far as the Herky Jerky DECnet stuff you need a Logical Topology
      Map of all Network Hardware and then pull lots of various bridge
      counters to check for errors. Also ask yourself some questions
      like is this related to a particular Cluster , Segment or time of
      day. Maybe you should consider renting an Ethernet or FDDI analyzer
      to see what's going on or try to track a pattern. 
    
      I hope someone can spend a couple of days on this. This is not always
      easy data to collect.
    
    							Good Luck,
    
    							  Rene'