PIM-URGENT

[Shuqian Yan <syan@jupiter.nal.utoronto.ca>]

Hi, Ahmed

I have been doing simulation using the PIM simulator in ns2 for a while, I
have some concerns about the pim simulator in ns2. There are certain
occurrence that PIM simulator is not working properly, i.e. it doesn't
forward the pkt to the desired receivers, the shared tree not build
correctly(there are no shared tree built at all, for some cases), and the
RP is not doing its job (the RP doesn't forward the decapsulated data pkt
to the receivers along the shared tree). Among 10 random graphs simulated,
there are 2-3 cases like this. When I look at the trace file, I can see
the join messages are correctly sent to the RP from individual receiver,
and I assume that's how the routing state on the reverse path been
established, based on the pim spec.

As an impression, pim simulator is a simplified version of pim spec (or
pimd)?? how simplify is it? I can see for some of the graphs, the
simulator does not perform pim function, such as building of shared tree
rooted at RP.

Another scenario I encountered in the simulation is that if there is a
direct link between the source and one of the receiver, the source will
straightaway send naked data packet to the receiver and bypass the RP. Is
this true only for leaf node? because if I have a chain of receiver
following the first receiver(who has a direct link to the source), then
this is a very serious problem, where is the shared tree and what the RP
is doing in this case? 

Could you share with me  your knowledge about this pim simulator, how can
I possibly check the routing table or the forward cache to know whether it
is properly set (I suspect some receivers didn't receive the data packet
is due to no forwarding cache built???)

The simulation result is very important as part of my research project, it
has to make some sense or be representative of pim in certain degree,
although there could be some simplification made compared to the spec, I
assume??  

Tks,

shuqian