There is no mistake actually...Just NS2 did not exactly follow the OSI
modelSome short cut to solve this problem: try to change the port
number of the packet into 255 when it was originated from the
source...Then the recv() can be invoked when the packet reaches the
destination!!!But in order for the upper layer to receive the packet, you
have to change the port number back to its original value and send it to
upper layer once recv() is called in destination.Hope it helps!!
I am a novice to the internals of ns-2. I would appreciate it if you can
tell me where the mistake it. Looking at the structural diagram did not
give me any answers w/ respect to multiple interfaces!
Thanks,
Sita
I am not sure if you are talking about this problem on routing
agent...If
yes, it is normal since if you checked the structurural diagram of a
mobile node in NS2, you can find out that once the packet reaches the
destination, the address classifier and port classifier will forward it
in
different way and the recv() in routing agent does not get invoked at
all...The solution also lies in that structural diagram!!!Think about
the
condition on which address classifier and port classfier will make
different selection!!
Hailun Tan
Hi There,
Thank you again for the reply. This is not my work, I am trying to use
something from NRL for my WSN work. Basically they have multiple
interfaces to a node. One channel carries just sensing info and another
channel is used for routing to sink. They want the sensing info to come
to
the agent, so that it can send info about it to the sink on the other
channel. That is why they have the up-target statement in the tcl code.
By
doing this, I was hoping the recv will come to the agent and it can
handle
it, but it does not. So I am not sure if the problem is in the
interface
implementation or somewhere else. Please share your thoughts.
Regards,
Sita
Hi again,
Yes I understand a little more of what you are trying to accomplish,
but
i
still have some questions; Are you modifying an existing routing
protocol
in ns2? Do packets get forwarded correctly from source to destination
according to your Mac level trace? If the packets don't get forwarded
there is as you say something wrong with the link layer's connection
to
the network layer (Your Router-module). When I designed my routing
protocol I started out with AODV and modified it. Also there are some
pictures of the architecture of the ns2 layers on the Internet that
may
help you. And finally, you say that you changed some thing in the Link
layer's up target so your routing module will be the receiver of
packets,
I'm not sure if you need to do that, if I remember correctly a
classifier
gets the packet from the link layer and the classifier decides if the
packet shall be sent to the routing module for processing (forwarding)
or
if the packet shall be sent to agent level (when the pac
ket have reached it's destination).
Regards Micke
- Originalmeddelande -
Från: Sita S. Krishnakumar [EMAIL PROTECTED]
Datum: Tisdag, Januari 24, 2006 16:58
Ämne: Re: [ns] Agent::recv method not reached
Mikael,
Thanks for your reply. I have more information that may shed more
light on
the problem.
I basically have a new agent designed. In my code, I specify that
the link
layer's 'up-target' is my agent node so that it can come to my
recv() for
processing. But looks like that is not working fine.
The MAC layer receives the packet but the agent does not. That is
why I
see it in the MAC trace but not in the agent trace. Even if it
does not
come to my recv(), it should go to the agent's recv() - but it
does not
go there either. So I am not sure where it goes altogether. Also I
am not
sure what the 'add-ll' does when an agent is created. I am trying
to add
someone else's work. I am not sure why they didn't have an add-ll
statement.
This is work from NRL and they say it works in 2.27, I am trying
to get it
to work in 2.29
Thanks,
Sita
Hi,
I had a similar problem, but I?m not sure if I understand
exactly what you
mean.
If you are sending one packet from source to destination
over some
number of intermediate nodes, you will only see the packet at
agent level,
if you have that trace level turned on in ns2 and you will only
see it at
the source and destination node. If you want to do something
with your
routing protocol when a data packet has been received at the
destination you have to understand that ns2's layers don't
exactly work as the OSI
reference model. When a data packet reaches it's destination a
classifier sends it to the agent layer, so you will never see
this packet at the
router layer(Network layer). If I remember correctly this has
some thing
to do with the mobile node class. I know for a fact that the AODVUU
implementation uses a newer class where packets are received and
sent bottom up through all layers. So you could
