[ns] Beowulf simulation

["Chad Fox" <chad.fox@mankato.msus.edu>]

For research involving message passing on a beowulf cluster, 
we want to simulate the network traffic on the cluster.

We are all new to NS, so we are spending more time trying to 
learn NS than working on our research.

Could anyone give us an example tcl script for creating a 
network topology of:
Multiple ethernet switches interconnected via Gb ethernet
(such that there is a Gb link between a switch and all the others)

	S1 -- S2
	 |\  /|
	 | \/ |
	 | /\ |
	 |/  \|
	S3 -- S4

and Multiple nodes connected to each switch via 100Mb 

We want to use FTP sources over TCP agents

Just an idea of how to construct switches and interconnect them
would be very helpful.

Thank you,

Chad Fox