Conference netcad::hub_mgnt

2090.0. "HUB90/DB90 config question" by ODIXIE::RICHARDSON (Are we there yet??) Fri Mar 10 1995 08:22

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Note 640.0                 DECHUB/DB90 config question                No replies
ODIXIE::RICHARDSON "Are we there yet??"              71 lines   9-MAR-1995 15:22
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     I was out at a customer site today and they were having "intermittent" 
     (i.e. unreproducable) errors (performance problems) on their network.  It 
     looks like the following:
     
     
     
     Location 1                           Location 3
     
     HUB_____FREP___fiber___FREP__
                                  |
     Location 2                   |    |---thinwire repeater
                                  |  __v____________________
     HUB_____FREP___fiber___FREP__|__|_ |
                                _____|_ |  Cabletron HUB
                               |     |  |
                               |   __|_ | 
                               |  |  |  |
                               |  |  |  |
                               |  |  |  |  
                               |  |  |__|___________________
                               |  |_______Goes to another Cabletron HUB
                         ___*__|_____      with a bunch (300) of PC's
                         |          |
                       Desta       Desta
                         |          |
                          Prism SONET
                            bridge
                               |
                          single mode
                             fiber
                               |
                          Prism SONET
                            bridge
                         |          |
                       Desta       Desta    Location 4
                         |___*_______|
                               |
                               |--3com bridge
                               |
                               |    |---DR90C
                               |  __v____________________
                               |__|_ |               |  |
                             _____|_ |               | <|--DECbridge 90
                            |     |  |               |  |
              Alpha________ |     |  |  DECHUB       | _|___H4005__thkwire
              6410                |  |               |  |
              Networked fax       |  |               |  |  
                                  |__|_______________|__|
                         
     Sniffers are located at *
     
     The sniffer in location 4 is showing a LOT (about 1 every 1-2 seconds) of 
     CRC errors.  However, it is also not showing any packet losses or 
     retransmits.  the sniffer in location 3 is not showing any errors.  The 
     exact error being logged is "JUNGLEMUX BRIDGE PROBE FRAME TO CLEAR LAN 
     ERROR. BAD CRC IS INTENTIONAL"  The Junglemux bridge is the Prism SONET 
     bridge.  This doesn't look to be an issue to me but they are wondering why 
     the errors are being logged.  (I recommended them calling Prism).
     
     The PC's in location 1, however are "reportedly" running slowly.  They 
     don't look to be violating any repeater rules, but there is an awful lot 
     of "stuff" off the repeater in location 4.  Could this be a problem?  
     Would it be better to put the thinwire segment coming from the SONET 
     bridge in location 4 directly onto the thickwire?  As it is, that's an 
     awful large "workgroup" off that hub (about 400 PC's and 5 Servers).
     
     Is there a better way to do this?  As it is, it is working, but it looks 
     rather shaky to me.
     
     thanks