addressing format questions

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

A browse through the comments in ns/tcl/lib/ns-address.tcl was
enlightening. 

I see that "mcast should be enabled before Simulator is inited (new
Simulator is called)" - yet a lot of Tcl sample code doesn't appear to
do this.

A play with hierarchical addressing was interesting; after
realising that:

$ns set-address-format expanded

could really just be considered legacy-compatible shorthand for an
equivalent: 

$ns set-address-format hierarchical 1 22

(and that the default smaller space therefore ought to be equivalent
 to:
 $ns set-address-format hierarchical 1 8 
 ...)

I was hoping that something of the form: 

$ns set-address-format hierarchical 1 10

would provide a workable solution for me with a customisable flat
address space of useful size, but alas it provided instead: 

can't read "cluster_num_": no such variable
    while executing
"eval $rl send-num-of-clusters $cluster_num_"
    (procedure "_o4" line 28)
    (Simulator hier-topo line 28)
[..]

...while setting multiple levels of hierarchy provided complaints of
the form:

Default value for cluster_num set to 4
 
can't read "nodes_num_": no such variable
    while executing
"eval $rl send-num-of-nodes $nodes_num_"

etc.

The start of Chapter 23 comfortingly suggests that large multicasts
are commonplace, so I must be suffering an installation-specific
problem... 

but, finally, how are all nodes specified as multicast nodes when
under SessionSim instead of Simulator? I've yet to get a SessionSim
script to work from the example code I've studied.

thanks,

L.

vaguely wondering if multipath can be combined with multicast in ns.

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