Re: Supporting large very large number of nodes

[Lloyd Wood <L.Wood@surrey.ac.uk>]

On Thu, 15 Oct 1998, Manor Shiri wrote:

> I used ns version 1.4.
> I run tests with 1000 nodes, 
> The main problem you will have is with memory.
> It depends on the amount of packets, and the network topology
> that you build.

I've run multicast simulations with 1680 nodes under the normal
simulator with recent snapshots, and _some_ of them have worked,
albeit inconsistently;  running-out-of-memory problems, I suspect,
since there are rather a lot of link objects too.

For large simulations where you're not interested in queuing delay,
you should apparently use SessionSim, which discards queueing
information etc to save memory. (Contrary to nsDoc, first part of
chapter 23, up to and including the latest release of 29 September,
SessionSim does not discard propagation delay - so I'm looking at it
with renewed interest.)

You'll need to use one of:
# traditional, deprecated
Node expandaddr

# new fashionable equivalent object syntax
$ns set-address-format expanded

# gives 1024 nodes with patch to support one level of hierarchy;
# (bit reserved for multicast) I haven't played with multiple levels.
$ns set-address-format hierarchical 1 11

after initialising the simulator to get a large address space to
create the nodes in.

hth,

L.

> On Thu, 15 Oct 1998, Arnis Ziedins wrote:
> 
> > Does somebody have  experience of running ns script with a very large number
> > of nodes? 
> > 
> > How many nodes running TCP can be simulated with ns?
> > For my experiment I would like to  have more than 1000 nodes.
> > Is it feasible with ns?

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>