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Date:      Wed, 20 Nov 1996 12:03:37 -0500
From:      exidor@superior.net (Christopher Masto)
To:        jgreco@brasil.moneng.mei.com (Joe Greco)
Cc:        exidor@superior.net (Christopher Masto), hackers@freebsd.org
Subject:   Re: Ipx to ip routing
Message-ID:  <199611201703.MAA11015@nimbus.superior.net>
In-Reply-To: <199611201618.KAA07394@brasil.moneng.mei.com>; from Joe Greco on Nov 20, 1996 10:18:43 -0600
References:  <199611201450.JAA06770@nimbus.superior.net> <199611201618.KAA07394@brasil.moneng.mei.com>

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Joe Greco writes:
> > Joe Greco writes:
> > > Ideally, in a school environment, each networked classroom or lab should
> > > be on its own subnet, or perhaps several subnets.  When the machines are
> > [...]
> > 
> > This falls apart when you have to deal with roaming.  If your "school
> > environment" isn't dealing with student laptops now, it will be within
> > the next few years.
> > 
> > The nicest solution I've seen is a large subnet (~13 bits) with smart
> > IP switches.
> 
> What do you do about IP address collisions, then???????  Good lord.  Hope
> you are great with an Ethernet sniffer, and your switches can trace on
> your behalf.  We had this problem at MEI, trust me, it is virtually
> impossible to track down transient collisions on such a large network.

The switches don't allow IP address collisions.  They associate a
hardware address with an IP address and talk to each other to keep
things in sync.  This is what they did where I went to school (RPI).
When you're in your room with a laptop, packets for your IP get
forwarded to that physical wire..  if you unplug the laptop and
reconnect it in a classroom, the switch sees your first packet and
updates its knowledge of where you are, physically.  If you try to use
the wrong IP, you are only affecting the physical segment that you are
on, because the switch knows it's not correct and probably even sends
an SNMP trap to let the administrators know.
-- 
Christopher Masto  .   .   .   .   Superior Net Support: support@superior.net
chris@masto.com  .   .   .   .   . Masto Consulting:           info@masto.com

On Machismo and Pestilence:
 In the early sixties, we were strong, we were virulent...
 - John Connally, Secretary of Treasury under Richard Nixon.



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