[Q] A bug of NAM ? ^.^

["Lee Jiwoong" <porce@viscom.kaist.ac.kr>]

Dear Seniors

I guess I found a very strange phenomenon of LAN, under nam.
My LAN is simple Mac/802_3 Channel. node 5,6,7,8 shares a LAN.

Node 5 is a router and Node 6 is receiving a multicast session with 
"join-group."
I just put: 
==========================================
$ns at 0.4 "$n(6) join-group  $R6L2 0x8023"
$ns at 0.7 "$n(6) leave-group $R6L2 0x8023"
==========================================
 without attaching receiver agent to node 6, intentionally.

This simulation works correctly. (That is, node 6 receives multicast
session well.) 

### Problem Statement:
However, when node 6 leaves group, Nam shows that NOT ONLY node 6
BUT ALSO node 7 and 8 generate control message AT THE SAME TIME.

The more strange thing is, Trace file and NAM trace file do not show that 
phenomenon in the sense of trace data. 

How can I understand this thing ? Why does ns run even though I missed receiver
agent attaching ?

Thanks in Adv.

Jiwoong Lee@KAIST



Env: ns2.1b5. 


....
$ns make-lan "$n(5) $n(6) $n(7) $n(8)" 10Mbps 5ms LL Queue/DropTail Mac/802_3 Channel
.... 

==========================================
.......
h -t 0.69961 -s 3 -d 5 -p rtp -e 210 -c 1 -i 364 -a 1 -x {0.1 128.19 -1 ------- null}
v -t 0.69999999999999996 sim_annotation 0.7 0.69999999999999996 6 leave-group 32803
r -t 0.70004 -s 3 -d 5 -p rtp -e 210 -c 1 -i 358 -a 1 -x {0.1 128.19 124 ------- null}
.......
==========================================
.......
- 0.69961 3 5 rtp 210 ------- 1 0.1 128.19 127 364
v 0.7 eval {set sim_annotation {0.69999999999999996 6 leave-group 32803}}
r 0.70004 3 5 rtp 210 ------- 1 0.1 128.19 124 358
.......
==========================================

---
 Jiwoong Lee @ KAIST EE