PEswitch/DECswitch Configuration Cautions


    PEswitch Configurations:

    The PEswitch  900TX  is a six port Personal Ethernet (dedicated 10
    Mb per user)  to  FDDI bridge.  The front panel Ethernet ports are
    all 10BaseT while the FDDI port goes to the DEChub backplane only  

    NOTE: There is  NO   front  panel  FDDI connection on the PEswitch
          900TX.  When  using  FDDI  TREES  in  the DEChub  backplane,
          only  ONE  DECswitch  or  DECconcentrator  will  be required 
          for tree configurations.

    The PEswitch 900TX has all the filtering  capablities  people have
    come to expect from a bridge (source address, destination address,
    protocol  type)  but  supports  a  very  small number of  Ethernet
    addresses  (only 64) as a Desktop Personal Ethernet product should. 
    Over 7,900 addresses can be learned through the FDDI port.

    The PEswitch  900TX  supports  bridge  filtering between all ports
    (Ethernet  to Ethernet  as  well  as  Ethernet  to  FDDI).    Full
    translation of packets between  Ethernet and FDDI (IEEE 802.1i) is
    supported as well as IP packet fragmentation per RFC-791 (Internet  
    Protocol),  RFC-1191 (Path MTU Discovery) and  specialized support 
    for Non-Translating Protocols (IEEE 802.1h) like AppleTalk.    The 
    PEswitch  900TX  is  a   bridge-only  product  and it  will NOT be 
    upgradable to support routing.   

    NOTE: The  PEswitch 900TX should NOT be used as a backbone network
          bridge  connecting multiple Ethernet segments with dozens of
          users each  to  an  FDDI  backbone  since it has the limited
          Ethernet address space.    If  a  customer wants a multiport
          Ethernet  to FDDI bridge,they  should  order  the  DECswitch
          900EF.  Customers attempting to  use the PEswitch 900TX as a
          backbone interconnect will be extremely dissatified with the
          performance since it will act as a  buffered  repeater  when
          the Ethernet 64 address table gets filled.   That means that
          all messages sent to address #65 and above will  be  FLOODED
          out all ports since the PEswitch will not know which port to
          send the message to.


    DECswitch Configurations:

     The DECswitch 900EF is a six port Ethernet to FDDI bridge with the
     ability  to  now  be  upgraded  with  a  brouter firmware  release
     There are four front panel 10BaseT Ethernet ports, two front panel 
     AUI Ethernet ports and a DAS ANSI optics FDDI port.

    NOTE: Careful  evaluation of the power requirements of the modules
          in any DEChub configuration should be done when using one or
          more  DECswitch  900EFs (aka DECbridge  900MX)  since  these
          devices  consume  more power (67.5 watts)  than  an  average
          module (typically 50 watts or less)