[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference netcad::hub_mgnt

Title:DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:NETCAD::COLELLADT
Created:Wed Nov 13 1991
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:4455
Total number of notes:16761

126.0. "DECbridge 90 and IP problem" by DPDMAI::DAVIES (Mark, SCA Area Network Consultant) Wed Jan 13 1993 17:07

    My customer has the following environment:
    
     === FDDI Ring ===
            ||             |      DEChub 90
    +-------||------+      |    +--------------+
    | DECbridge 600 |      |----| DECbridge 90 |
    +---+--------+--+      |    +-------+------+
        |        +---------|    | DECrptr 90C  |
        |  +-----------+   |    +-------+------+
        |  | PATHworks |                |  
        +--| VMS w/UCX |                |  
        |  +-----------+                |  +-----------+
        |                               |  | PATHworks | #2
        |  +-----------+                +--| DOS w/TCP |
        |  | PATHworks | #1             |  +-----------+
        +--| DOS w/TCP |                |
        |  +-----------+
        |
        |
    
    Here is the situation:
    
      The PW4DOS PC #2 boots up (locally) and makes its conenctions to the VMS
      PATHworks Server (across the bridges).  Everything works... as long
      as there is not any significant amount of idle time on the link, ie,
      don't walk away and get a cup of coffee.  Because, when you get back,
      the the PC will be locked up and must be rebooted.
    
    This environment works fine when the protocol was DECnet, which it was
    until they recently decided to start using TCP on their backbone.
    
    If they reboot the systems using DECnet as the transport (same PC),
    there are no problems at at.
    
    There are no problems what so ever when PW4DOS PC #1 (configured
    identically to #1) boots up and uses TCP/IP as the transport.  The
    links stay up no matter how long you have an idle PC (TCP link). 
    Because of this, it seems/appears to be a TCP/IP bridging problem in
    either the DECbridge 600 or DECbridge 90.
    
    They are running PATHworks for DOS V4.1A and PW4DOS TCP V2.0.
    
    Are there any known problems with the DECbridge 90 and the TCP/IP
    protocols?
    
    ANy other thoughts?
    
    Thanks,
    
    Mark
T.RTitleUserPersonal
Name		DateLines
126.1other configurationsDPDMAI::DAVIESMark, SCA Area Network ConsultantWed Jan 13 1993 17:3681
    This is an addition to .0:

    They hav tried the following configuration and it works:
    
        +-------+         +-----------+
        | DEMPR |---------| PATHworks |
        +---+---+         | DOS w/TCP |
            |             +-----------+
    ========+=================+==============
                              |
                        +-----+-----+
                        | PATHworks |
                        | VMS w/UCX |
                        +-----------+
    
    

    They have tried the following configuration and it works:
    
                       DEChub 90
                    -+-+-+-+-+-+
                             |D|                       +-----------+
                             |E|BNC side port|---------| PATHworks |
                             |C|                       | DOS w/TCP |
                             |b|                       +-----------+
                             |r|
                             |i|
                             |d|
                             |g|
                             |e|
        +-------+            | |
        | DEMPR |---------BNC|9|
        +---+---+            |0|
            |                +-+
    ========+=================+==============
                              |
                        +-----+-----+
                        | PATHworks |
                        | VMS w/UCX |
                        +-----------+
    
    

    They have tried the following configuration and it does NOT work. 
    Please note that the ONLY change from the previous working
    configuration is that a DECrepeater 90C was placed in the DEChub beside
    the DECbridge 90 (but nithing was connected to it.
    
                       DEChub 90
                    -+-+-+-+-+-+
                           |D|D|                       +-----------+
                           |E|E|BNC side port|---------| PATHworks |
                           |C|C|                       | DOS w/TCP |
                           | |b|                       +-----------+
                           |r|r|
                           |p|i|
                           |t|d|
                           |r|g|
                           | |e|
        +-------+          |9| |
        | DEMPR |-------/  |0|9| /--+------+
        +---+---+          |C|0|BNC port|--+
            |              +-+-+
    ========+=================+==============
                              |
                        +-----+-----+
                        | PATHworks |
                        | VMS w/UCX |
                        +-----------+
    
    
    Strange you say?  No kidding.  It has me stumped.  It makes it appear
    as though there are problems with TCP/IP on the DECbridge 90 only when
    a DECrepeater 90C is in the slot next to it.
    
    Any toughts/comments are appreciated.
    
    Thanks,
    
    Mark
126.2Client getting aged out of forwarding database?MEMIT::FORRESTWed Jan 20 1993 14:1513
	Mark, my initial guess is that a Pathworks PC running DECnet sends 
	out periodic MOP SYSID packets, and a Pathworks PC running TCP/IP 
	doesn't. In other words, if you leave the TCP/IP node alone, it 
	doesn't send any packets. This would cause a bridge (FDDI or Ethernet)
	to age it out of the database. The server gets no response then, 
	and the link gets dropped. 

	You might see if the time it takes to drop an idle link is related 
	to the shortest aging time of the bridges that may be inbetween 
	the client and server.

	jack