Re: setting up a LAT service via a terminal server

From: Albrecht Schlosser (ajs856_at_tiscali.de)
Date: 08/25/03

  • Next message: Phillip Helbig: "Re: setting up a LAT service via a terminal server" 
    Date: Mon, 25 Aug 2003 18:21:44 +0200

    Phillip Helbig wrote:
    >
    > Apart from the consoles, I have a VT320 connected to a serial port of a
    > node in my hobbyist cluster. If that node is down for some reason,
    > however, then of course one can't log in via that terminal. (The
    > terminal in question is in my son's bedroom. How many 9-year-olds do
    > you know who know how to use EDT? One of my biggest triumphs was when I
    > heard him say "Mama's PC doesn't have a PROPER keyboard"!) Thus, I
    > would like to have the terminal connect to the CLUSTER instead of to a
    > specific node.
    >
    > It seems the way to do this would be to connect via a terminal server.
    > I have a DECserver 250 and a DECserver 200/MC. Presumably these will
    > work fine for what I want to do. I also have the necessary cables etc.
    > [...]
    >
    > At the moment, the cluster has a VAX at 7.3, a VAX at 7.2 and an ALPHA
    > at 7.2-1. There is no DECnet running.

    If you don't have DECnet running, then you need LANCP to configure the
    MOP loading. As others wrote about the DECserver, LANCP also has set and
    define commands. To enable MOP (aka DLL), you should do something like

    $ lancp :== $lancp
    $ lancp def dev ewb0 /mop=(enable,exclusive,noknown)
    $ lancp list dev ewb0 /mop

    Device Listing, permanent database:
                  --- Downline Load Service Characteristics ---
      Device State Access Mode Clients Data Size
      ------ ----- ----------- ------- ---------
      EWB0 Enabled Exclusive NoKnownClientsOnly 246 bytes
    $

    (Replace ewb0 with your network device, see "LANCP show device). See
    LANCP HELP (or the docs) for details.

    This enables MOP loading for all clients, even "unknown" clients, if
    they request a specific file (PR0801ENG.SYS for DECserver 200). You need
    only this file to get a DS-200 started. For LANCP, the load file
    directory is defined by the logical name LAN$DLL:

    $ sho log lan$dll
       "LAN$DLL" = "SYS$SYSROOT:[MOM$SYSTEM]" (LNM$SYSTEM_TABLE)

    Use

    $ lancp sho mop

    LAN MOP DLL Status:
      EWA0 disabled
      EWB0 enabled in exclusive mode for all requests, data size 246 bytes

           #Loads Packets Bytes Last load time Last loaded
           ------ ------- ----- -------------------- -----------------
      EWA0 0 0 0
      EWB0 1 1712 207763 20-AUG-2003 17:18:17 08-00-2B-16-5F-58

    to see the MOP/DLL status (MOP and DLL are synonyms wrt LANCP).

    As you can see, I have LANCP DLL enabled on EWB0 only, because EWA0 is
    served by DECnet MOP/DLL (***):

    $ ncp sho circ ewa-0 char

    Circuit Volatile Characteristics as of 25-AUG-2003 18:20:30
     
    Circuit = EWA-0
     
    State = on
    Service = enabled (***)

    > LAT is configured so that one
    > can SET HOST/LAT to and from any machine in the cluster. With TCPIP I
    > have a cluster alias so that to the outside world, the cluster behaves
    > as one machine. Ideally, I'd like the same functionality with LAT.

    As others stated, more than one node can offer the same service. There
    are examples in SYS$MANAGER:LAT$SYSTARTUP.TEMPLATE. If you have not done
    so, copy this file to SYS$MANAGER:LAT$SYSTARTUP.COM and modify it as you
    need. In fact, this file is called by LAT$STARTUP.com, which is called
    from SYSTARTUP_VMS.COM.

    > (In fact, since the connection to the outside world is via a DSL
    > switch/router which does PAT and forwards incoming connections to the
    > cluster alias, not only is there just one address for INcoming
    > connections, but just one address for OUTgoing connections as well, the
    > external address of the router. (Normally, a cluster alias applies to
    > just incoming connections, whereas each node will use its own address
    > for outgoing connections.))
    >
    > Load-balancing would be nice just to get some experience with it, but
    > for my purposes failover (like with the TCPIP cluster alias) would be
    > enough.

    You don't want to route LAT over the internet, do you? LAT can't be
    routed (LAN only), but you surely know this :-).

    > While I'm at it, I have an LNO3 sitting around. Can I connect that to
    > the terminal server as well?

    Yes.

  • Next message: Phillip Helbig: "Re: setting up a LAT service via a terminal server"

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