Ideas on a network design?

Tim Keanini <blast@worldbit.com> Tue, 11 April 1995 04:45 UTC

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Date: Mon, 10 Apr 1995 21:39:35 -0700 (PDT)
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From: Tim Keanini <blast@worldbit.com>
To: rreq@isi.edu
Subject: Ideas on a network design?
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Hello,
I am new to this list and if my posting here is not the interests of
this mailing list please let me know so that I may take my question
elsewhere.
Here is my (long) post to share with you all:

We have a network that is 'Flat'.
There are two buildings and about 400 or so employees.
We have a Kalpana Ether Switch that helps us distribute the network
bandwidth.  The network primarily is a mature IPX and Appletalk
network.

+-----------------------------------------+
|          Kalpana ETher Switch           |
|1st    2nd    3rd    4th    5th     6th  |
+-+------+------+------+------+-------+---+
  |      |      |      |      |       |
  |      |      |      |      |       |
  |      |      |      |      |       |
HUB     HUB    HUB    HUB    HUB     HUB

Connection 1 through 5 are being used for IPX and Appletalk traffic.
The network connections 2 and 5 going to Novell servers in FULL DUPLEX mode. 

Here is my problem.
I now have to route IP in my internal network and I am going to have
to stick IP routers on the internal LAN.

In the Ether Switch manual, they show the solution like this.  If you
network used to look like this:

BEFORE
         router              router            router
           |                  |                  |
-----------------------------------------------------------------------
                    |                   |                |
                  router              router           router

AFTER

+---------------------------------------------+
|          Kalpana ETher Switch               |
|1st     2nd     3rd     4th     5th      6th |
+-+-------+-------+-------+-------+-------+---+
  |       |       |       |       |       |
  |       |       |       |       |       |
  |       |       |       |       |       |
router router  router  router  router  router
 
The idea here with Kalpana is that via the Ether Switch, each port
will get its share of the ether speed since it routes on the first
64k.

Well, if I have to buy 6 routers, I will limit the growth of the
network because if I dont buy routers that have all the snappy feature
that the IPX and Appletalk network people want(ie full duplex, 100mbit
etc.etc.)  
(I am not sure if I am being clear here but stay with me)

So, this is that I am going to do to make everyone happy.

+---------------------------------------------+
|          Kalpana ETher Switch               |
|1st     2nd     3rd     4th     5th      6th |
+-+-------+-------+-------+-------+-------+---+
  |       |       |       |       |       |
  |       |       |       |       |       |
  |       |       |       |       |       |
 HUB     HUB     HUB     HUB     HUB   +--+-------------+
                                       | HUB            |
                                       + +--+--+--+--+-++
                                         |  |  |  |  |  \_router to intenet
                                         |  |  |  |  |      
                                  +------+--+--+--+--+-----+
                                  |     16  17 18 19 20    |
                                  |                        |
                                  |PC with 5 ethernet cards|
                                  +------------------------+
This PC is running UNIX with IP forwarding in the kernel.
It has 5 ethernet card that are on networks xxx.xxx.16.0 though
xxx.xxx.20.0

The internet router sits on the xxx.xxx.16.0 network and routes out
to the internet via a firewall.

Please forgive me if this diagram looks silly but it all started when
I was just going to get my block of class C's, 
x.x.16.0, x.x.17.0, x.x.18.0, x.x.19.0, x.x.20.0, x.x.21.0, x.x.22.0,
and x.x.23.0 networks and pop them on a supernet but masking with 
255.255.248.0 and a broadcast of xxx.xxx.23.255
Well, to my suprise, there are a lot of IP stacks on
PC's that will not let you supernet like this with a block of class
C's
If all my internal hosts were UNIX machines, 
I would be set but they are mostly Macs and Windows machines.
So that is the method to my madness.  That is the reason that I have 5
ethernet cards all with a 255.255.255.0 mask.

The basic idea really is that all IP routing will happen on the 6th
channel of the ether switch.

If anyone would like to talk to me about this, please mail me.  I am
no network guru and would like to share this idea with some who has
setup a network with some of the same problems that I face.  If the
problems that I face are not clear, write me and I will try and make
my examples clearer.

--blast



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