🚀 go-pugleaf

Steve Hubert replied to my posting of 20-Jun-91:

|On Thu, 20 Jun 91 22:11:40 EDT, Watt-Alan@mickey.ycc.yale.edu wrote:
|
|> Subject: Re: backplane backbone, routing or bridging?
|> To: hubert@cac.washington.edu
|> cc: cisco@spot.colorado.edu
|>
|> ...
|>
|
|> However you do not have to assign a whole subnet to each point-to-point
|> ethernet.  You can have a single subnet which is shared by all the
|> point-to-point ethernets on both ends.  Assuming you subnet a class B
|> on an 8-bit boundary, and the "point-to-point cloud" is subnet 100,
|> you could define the subnet mask 255.255.255.252 to allow 6 bits
|> of "sub-subnet" and 2 bits of "host" (0 is reserved, 3 is broadcast,
|> 1 and 2 are the two endpoints.
|
|I don't understand how to do this with cisco equipment.  My understanding is
|that the cisco has a single netmask for a network.  How do you get the
|variable length mask idea to work?

I think my fingers ran amok before my mind was properly engaged.  I have
actually never tried this and now that I think about it, it is quite
likely to get you in trouble.  However, I am quite sure that nothing
stops you from getting yourself a new class C network and subnetting
it as described above.  This still saves you from wasting unnecessary
subnets of your class B.

For all that, it may actually work to sub-subnet your class B.  On
a typical BSD system, datagrams would be output on the proper interface,
but the routing protocol daemons might get hopelessly confused.  Perhaps
the same thing would happen on a cisco box (or is it "Cisco box" these
days?).

	- Alan S. Watt
	  High Speed Networking, Yale University
	  Computing and Information Systems
	  Box 2112 Yale Station
	  New Haven, CT  06520-2112
	  (203) 432-6600 X394
	  Watt-Alan@Yale.Edu


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