[ns] Release announcement for NS with NixVectors

[George Riley <riley@cc.gatech.edu>]

The COMPASS research group at Georgia Tech is please to release
the "Nix-Vector NS" modifications to the ns community.  The Nix-Vector
NS contains a new routing method for ns that uses substantially less
memory than the default routing method in the standard ns.  A Nix-Vector
is essentially a method of source routing, that allows the simulated
routers to make routing decisions without using routing tables.  With
Nix-Vector ns, you have the memory benefits of the ns hierarchical routing
methods without the requirement for a structured topology or assigning
the routing heirarchy manually.  For more details, and download instructions,
see our web page at:

http://www.cc.gatech.edu/computing/compass/nvns

A copy of the FAQ is below.

Contact George Riley (riley@cc.gatech.edu) with any questions.

This work is supported in part by the US National Science Foundation under
contract ANI-99-77544.

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NSNV Frequently Asked Questions

Is NixVector routing appropriate for all existing NS scripts?
No.  Since NSNV does not compute routing tables, any simulation which
uses the routing tables for anything other than unicast packet forwarding
will likely not work.  In particular, multicast flows cannot use
NixVector routing.

How do I know if NixVector routing is appropriate for my simulation?
The short answer is if you don't know what a "slot" is in NS terminology,
and you don't use multicast, your simulation has a good chance of
working with NixVector routing.

Since NixVector routing is not appropriate for all simulation scenarios,
what is it good for?
Any simulation that is concerned with end-to-end unicast flows under a
fairly large topology can benefit from NixVector routing.

What changes do I need to my ns script to use NVNS?
To enable NixVector routing in NVNS, just include a single ns command:
(this command must be executed PRIOR TO creating any nodes)
      $ns set-nix-routing

Does the inclusion of the NixVector modifications to ns break anything?
No, with the NixVector modification included, all ns validation tests produce
the same results as the original ns.

What is a NixVector anyway?
NixVector routing is described in detail in two research papers:
      http://www.cc.gatech.edu/~riley/papers/nsnv.ps.gz
      http://www.cc.gatech.edu/~riley/papers/nixvec.ps.gz

How much memory reduction will I see using NVNS?
It depends.  If your simulation has a large number of nodes (1000 or more)
and a smaller number of connections (100 or so), your savings will be
substantial.  If you only have a small number of nodes, your savings will be 
negligible or negative.

Where can I get the code for NVNS?
      http://www.cc.gatech.edu/computing/compass/nvns/index.html

					
			-George F. Riley (riley@cc.gatech.edu)