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From: markat@cyrano.llnl.gov (Mark Tassinari)
Newsgroups: comp.dcom.sys.cisco
Subject: Network config questions
Message-ID: <32870@boulder.Colorado.EDU>
Date: 5 Mar 91 05:03:07 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 48


Greetings.

We just purchased a number of cisco AGS+ routers and intend to begin routing 
IP, DECnet and eventually Appletalk.  I have heard somewhere that sites are
configuring their nets to take advantage of cisco's high bandwidth backplane.
We were hoping to do this also, but are running into some problems with regard
to IP addressing.  I hope someone that has traveled this road can offer some
advice on how to set up the IP addressing.

The concept was simple.  Rather than having a 10Mb ethernet connect all the 
node routers together we would connect them to a single cisco and use the
backplane as the backbone.


           Bld1  Bld2  Bld3
	     \    |   /
              \   |  /
	     ---------   ---------   ---------   ---------
	    |  Node1  | |  Node2  | |  Node3  | |  Node4  |
	    |  cisco  | |  cisco  | |  cisco  | |  cisco  |
	     ---------   ---------   ---------   ---------
	          \          \           /          /
		     \        \         /        / 
	                \      \       /      /
       		           \    \     /    /
			      \  \   /  /
	                     -------------
			    |     hub     |
			    |    cisco    |
			     -------------


Each of the Bldx networks is assigned one class B subnet.  My big question is,
what's the best way to address the node<->hub links?  Its seems wasteful to 
use a class B subnet for each.  We tried mucking with the netmask to make a
single subnet into a number of smaller subnets and using one of these small
subnets on each link.  We then got into trouble with conflicting netmasks.  

Is there a better way?

Thanks.


~~~~~~~~~~~~~
Mark Tassinari				markat@cyrano.llnl.gov
Lawrence Livermore National Lab		(415) 422-4090
PO Box 808   L-408			Livermore, CA 94550