I have deduced that the error is due to rescheduling the same event by ns2
which is the copies of the packet to be sent overall interfaces. So, I must
make the copied packets to appear as different events to ns2. For this
purpose I have changed the uid_ of the copied packets to be different from
each other as follows:
/*----------------------------------
int uuu = p->uid_;
if(nIfaces) {
for(int i = 0; i < nIfaces; i++){
Packet *p_copy = p->copy();
p_copy->uid_ = uuu--; //to avoid getting uid > 0
Scheduler::instance().schedule(targetlist[i], p_copy, 0.);
}
Packet::free(p);
}
------------------------------------*/
and it works 100%. Is my observation correct? I will appreciate any usefull
comments.
Thanx,
Ghada
Ghada Al-Mashaqbeh wrote:
>
>
> Dear all,
>
> I am working with ns-2 2.31, I have added the multi-interface capability
> according to Multi-interface support howto, by Ramon Aguero
>
> I have modified the routing agent (I have worked with AODV) to support
> broadcasting packets on all interfaces as follows:
>
> if(nIfaces) {
> for(int i = 0; i < nIfaces; i++){
> Packet *p_copy = p->copy();
> Scheduler::instance().schedule(targetlist[i], p_copy, 0.);
> }
> Packet::free(p);
> }
>
> when I run my simulation scenario ( which is a static grid topology of
> 20 wireless nodes)
> I got the error of:
> "Scheduler: Event uid is not valid" at time 67 sec of the simulation
> time.
>
> I have searched the mailing list and the available sources about this
> error, I have fixed all MAC bugs (most of them are already fixed in the ns
> distribution), then I have found a FAQ in which the following is stated:
> "2. You are dealing with packets. A packet is also a kind of event to be
> scheduled and a UID is associated with it. When you create a copy or alloc
> again before freeing it, due to the same packet with a positive UID, it
> cannot be scheduled again. "
>
> So, I gussed that the error is in copying the packet to be sent on all
> interfaces (in the modifed code presented above). So, I have modifed that
> code as follows to free the copies of the packet:
>
>
> if(nIfaces) {
> for(int i = 0; i < nIfaces; i++){
> Packet *p_copy = p->copy();
> Scheduler::instance().schedule(targetlist[i], p_copy, 0.);
> Packet::free(p_copy);
> }
> Packet::free(p);
> }
>
> but when I run my simulation scenario I got:
> " segmentation fault 'core dumped'"
>
> I am sure that the error is in the routing agent module, since I have
> run simulation scenarios without the modified AODV and it worked, but I
> cannot congifure where the bug is.
>
> Is there anybody have worked in multi-interface support for AODV? have
> you faced such problem in your testing?
>
> any useful comments and hints will be highly apreciated.
>
> Thanx,
>
> Ghada
>
>
> ---------------------------------
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>
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