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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

1445.0. "PEswitch vs. DECswitch" by NWD002::TUTAK_PE (Garbage Pie: Gimme Two !) Mon Sep 19 1994 15:51

    
    What are the differences between the new PEswitch 900TX and the DECswitch 
    900EF (nee DECbridge 900MX) ? I know the physical interfaces on the TX 
    Ether ports are all RJ45, EF is a blend of AUI and RJ45, but the
    information given on the Fact Sheets seems pretty ambiguous.
    
    Does TX support the routing s/w planned for EF ? What are the
    differences in the bus architectures (if any)? Does TX contain the 400 Mbps
    internal bus that was planned for it, or has that been scaled back ?
    
    Just trying to sort out fact from fiction. Thanks !
    
    Peter
T.RTitleUserPersonal
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1445.1NETCAD::ANILMon Sep 19 1994 23:5138
    Some of the significant differences:
    
    1. The PEswitch is cheaper.
    
    2. It supports a maximum of 64 addresses on all 6 Ethernets combined,
       so it MUST be used as a Personal Ethernet switch and not as a full
       bridging switch.  That is, only a few Ethernet stations can be
       connected to each port (an average of 64/6, but it's the total
       that counts).  By comparison, the DECswitch 900EF can be used as a
       full bridge; its 8000 address capacity is shared by all its LANs.  As a
       result, if you try to save money by buying the PEswitch rather
       than the DECswitch, you pay for it in the long run due to
       a lot of unnecessary flooding when the Ethernet database capacity is
       exceeded.  (Note that the FDDI is still treated as a full LAN
       and has plenty of database room, over 7000).  There will be counters
       in HUBwatch which will start incrementing if the PE's get overused.
    
    3. On the PEswitch, there is no FDDI connector on the front panel.
       The FDDI is available only for connection into the hub
       backplane.  A 400 Mbps internal bus is not present, however you
       could view the FDDI as a high-speed interconnect between
       these PEswitches.  Note that with the FDDI-capable docking
       station, you could bring out the FDDI in standalone mode.
    
    4. The Ethernet ports are not only all UTP, but they are cross-wired
       rather than straight-through - like a repeater.  Think of Personal
       Ethernet switches as replacements for repeaters, which give each
       port a full 10 Mbps instead of the SHARED Ethernet which the
       repeaters give you, and you get the idea.  It increases the
       bandwidth delivered to the desktop without rewiring.
    
    5. The PEswitch does not have the memory to accomodate routing
       functionality, while the DECswitch hardware supports future routing
       upgrades.
    
    The max throughput is about the same as the DECswitch: 60 Kpps.
    
    Anil
1445.2ThanksNWD002::TUTAK_PEGarbage Pie: Gimme Two !Wed Sep 21 1994 01:266
    
    Thanks, Anil. That's what I was looking for. I knew it was cheaper. I
    just wanted to know why the delta.
    
    Peter
1445.3NETCAD::ANILWed Sep 21 1994 18:165
    In describing these to customers, it would be best to refer to
    DECswitch 900EF as a Departmental Switch and the PEswitch 900TX
    as a Desktop Switch.
    
    Anil
1445.4STRWRS::KOCH_PIt never hurts to ask...Tue Jan 24 1995 00:184
    In regard to the fact that the FDDI has 7000 addresses, can you string
    multiple PEswtiches together and each one maintains its store and
    forward database? That is, is the 64 address limit affected by the
    number of addresses floating around the FDDI?
1445.5Yes, you can stringDELNI::PIEPERThu Feb 23 1995 11:477
    The PEswitch supports a maximum of 64 MAC addresses across the six
    Ethernet ports and 7936 MAC addresses through the FDDI port.  So that
    means we can connect DOZENS of PEswitches via FDDI and even connect
    them to other FDDI departmental bridges and everything will work fine.
    The 64 MAC address limitation applies to the Ethernet ports only. 
    Putting more than 64 stations on the Ethernet ports will cause the
    switch to start flooding packets.