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NAM/Javis
Description
Network
Animator (NAM) and Javis, its Java counterpart, are packet flow
animators. Simulation
results from Network Simulator (NS) can be captured and fed into
NAM after a run has completed.
NAM will plot the simulated network and show animated
packet flows between nodes.
Layout
NAM uses a
topological force-directed layout algorithm.
This class of algorithms can be used to lay out general
graphs with hundreds of nodes.
The intuition behind the algorithm is as follows.
First, place nodes randomly on a plane.
Calculate the shortest path between any two nodes in the
graph. Attach a
spring with that length between every pair of nodes.
On each iteration, release the springs and let the nodes
fall into their lowest energy state.
In the resulting graph, the Euclidean distance between each
pair of nodes will approximate the shortest path between them.
Unfortunately, any 2-D layout of a large general graph will
be cluttered.
Interactivity
The
navigation controls for NAM are fairly primitive.
Javis doesn’t even support zooming. NAM can animate
packet flows and queue sizes.
The animation interface resembles that of a VCR.
Availability
Both NAM and Javis are
freely available. NAM
can be found on the NAM
website. Javis
can be downloaded from ftp://cs.ucl.ac.uk/nets/src/jns.
NAM has been released on
Windows, FreeBSD, Linux, Solaris and SunOS.
Using
NAM/Javis
NAM’s input
file format is confusing, and the documentation is obsolete.
Frankly, I haven’t gotten it to work yet.
The input file contains a number of events that can be used
to define nodes, links, queues, and packets.
Instead of specifying the x,y coordinates of each node, NAM
requires the user to give the angle and length of each link.
This can be awkward when attempting to manually plot a set
of points.
Links
NAM
website
Javis
FTP site
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