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From: cmilono@netcom.COM (Carlo Milono)
Newsgroups: comp.dcom.lans
Subject: Re: 10Base-T hubs(now Bridging)
Message-ID: <1991Apr26.032625.26585@netcom.COM>
Date: 26 Apr 91 03:26:25 GMT
References: <1991Apr17.212748.7165@shl.com> <14740@darkstar.ucsc.edu> <1991Apr21.021222.947@engin.umich.edu>
Distribution: usa
Organization: Netcom - Somewhere in the S.F. Bay Area
Lines: 47

In article <1991Apr21.021222.947@engin.umich.edu> jal@acc.flint.umich.edu (John Lauro) writes:
>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...
>	......[stuff deleted to protect innocent....]

>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

       Ah, filtering is one thing, but forwarding is another and is
always slower by quite a bit!
>.  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...

       And, when you bridge, you are going to bridge to all others? 
I suppose what you are asking for is a *star* arrangement, much like
RS232-C, that supports *private* 10Mbps to a server from the client.
No need for Carrier Sense, there would be no Multiple Access, and
you would not need to Detect Collisions...= not 802.3 CSMA/CD!  And
how would you support multiple hosts?  Link them via SONET/FDDI and
'telnet' through your 'local' host.

>  The closest I've seen done is to have many small hubs,
>and bridge each of the hubs into a central hub.

...and you had better have a server on each hub or else you suffer the
fate of the forwarding rate...

-- 
+--------------------------------------------------------------------------+
|  Carlo Milono:  cmilono@netcom.apple.com   or   apple!netcom!cmilono     |
|"When a true genius appears in the world, you may know him by this sign,  |
|that the dunces are all in confederacy against him."   - Jonathan Swift   |