Newsgroups: comp.dcom.lans
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From: jal@acc.flint.umich.edu (John Lauro)
Subject: Re: 10Base-T hubs
Message-ID: <1991Apr21.021222.947@engin.umich.edu>
Sender: news@engin.umich.edu (CAEN Netnews)
Organization: University of Michigan - Flint
References: <1991Apr16.182217.6151@netcom.COM> <1991Apr17.212748.7165@shl.com> <14740@darkstar.ucsc.edu>
Distribution: usa
Date: Sun, 21 Apr 1991 02:12:22 GMT

In article <14740@darkstar.ucsc.edu> woody@ucscb.UCSC.EDU (Bill Woodcock) writes:
>        > phil@shl.com (Phil Trubey) writes:
>        > Has anyone heard of a product that does per
>        > port *bridging* inside a 10BaseT hub instead
>        > of per port repeating?  ie. Packets would be
>        > sent into the hub and the hub would switch it
>        > out to the sole destination port. With a fast
>        > enough bridging unit, you could up the
>        > bandwidth of your ethernet hub by an order or
>        > magnitude or two...
>    
>    networks.  It bottlenecks any transmissions to faster media, (FDDI, in
>    this case, instead of Ethernet) and  it  renders  all  your  expensive
>    network  troubleshooting and packet analysis utilities useless. If the
>    hub's management software is, in and of itself, smart enough  to  give
>    you  those  same  features,  (as  is  partially  the  case  with Tribe
>    Computing's AppleTalk hub) then you're partially off the hook, but how
>    many  Ethernet  hardware  comapnies  would  you  trust  to  write good
>    software?  The only way to get around the gatewaying bottleneck is  to
>    add  multiple  gateways  per hub, which greatly complicates addressing
>    and troubleshooting, and starts costing _a lot_.

The hub would have to be extremely fast to bridge a large number of
ports.  Assuming worst case...  Number of ports * the speed of ethernet.
With 11 ports, you are talking about > FDDI speed.  Migrating to
FDDI should be easy, if it can be integrated right into the hub.  The
only problem is it wouldn't be cost effective at this point.  The best
price I seen on bridges that can handle full speed ethernet (filter rate
of 29,600 packets/second) are about $2,300.  I would hate to think of the
cost for 50 port or 100 port hub with bridging on each port.  (Could be
better than FDDI if affordable.  You could then run FDDI to your servers
on the same hub, etc...)  It would certainly eliminate any problems
of collisions...  The closest I've seen done is to have many small hubs,
and bridge each of the hubs into a central hub.