Re: Multicast Questions

[Polly Huang <huang@tik.ee.ethz.ch>]

James,

Simulator instproc get-mcast-tree { src grp } {
        $self instvar link_ treeLinks_
        # iif == -2: from local
        set tmp [$src getRepByIIF $src $grp -2]
        if {$tmp == ""} {
                $self flush-trace
                error "No replicator for $grp at [$src id]"
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        }

It looks like the second error you encountered is due to no 'group
replicator for the (src grp) given'.  You should make sure you actually
have receivers joined to the 'grp' and the data sent from 'src'.
According to the script you attached, at least 'group' should be '$group'
(if that's not a typo in only the email) and you should probably call
'get-mcast-tree' later in the simulation to give the DM and data source
some time to set up the replicators (usually the (S,G) replicators are not
created in the setup phase). Just a couple speculation what the problems
might be. Hope this helps.  

In general, it's good to create a simple script, visualize it with nam,
(just to make sure it works and you're not overlooking something) and then
try to add more functions for your purpose.

        set mproto DM
                set mrthandle [$ns mrtproto $mproto {}]
                ........
                $ns join-group receiver_agent group            
        $ns get-mcast-tree $node($src) $group #src is srouce node id

Cheers,
-Polly


On Tue, 11 Jan 2000, jamester wrote:

> > James,
> > 
> > 0x8002 is considerred a unicast address when used with 'expanded'
> > addressing.  It is recommended to use 'Node allocaddr' instead of manually
> > configuring mcast addresses (unless you know the address format very
> > well).  
> > 
> > Cheers,
> > -Polly
> > 
> > >     	while executing
> > > 	"error "No replicator for $GROUP_ at [$src id]""
> > >     	(procedure "_o3" line 7)
> > >     	(Simulator get-mcast-tree line 7)
> > >     	invoked from within
> > > 	"_o3 get-mcast-tree _o53 0x8002]"
> > > 
> 
> Dear Polly Huang
> 
> Using Node allocaddr eliminated error of my first question - no target for slot
> error.  However, it did not solve problem with getting multicast tree.
> I am using "ns 2.1b4".  I notice that CtrMcastComp.tcl has routine for
> computing multicast tree.  Is there any way to find out which nodes are in the
> tree?  
> 
> Thanks
> 
> -James Kwon
>