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Re: loss of original packet type info when tracing multiple protocols.




Only packets generated by the mac-802.11 protocol such as RTS, CTS and ACK 
packets have PT_MAC as the packet type in the common header (if you look at 
mac-802_11.cc, you'll notice the packet type is set to PT_MAC only in sendRTS, 
sendCTS and sendACK methods). I dont think the packet type is changed to 
PT_MAC for packets generated by higher layer protocols.

Satish


> Hi,
> 
> - How does one retain the original information in the common header -
> the packet type being the most important- when using nodes consisting of
> multiple protocol layers and tracing for some of these layers is
> required?
> 
> Consider for example a node containing a MAC layer and a TCP agent.. The
> ns/cmu trace objects generate their traces by looking at the packet type
> field in the common header. For a MAC packet, the type therefore needs
> to be changed from PT_TCP  to PT_MAC in the sending MAC object (I know
> this is being done in mac-802_11.cc when a Packet is passed to the
> channel). On the receiving MAC side, the packet type should be changed
> back to PT_TCP but I don't see how this information can be retained. I
> also don't see how / if  this is being done by the MAC object in
> mac-802_11.cc
> 
> I guess there are ways to avoid it, e.g. packing the original (TCP/IP)
> packet into the data field of the Packet transmitted by MAC (and
> unpacking at the MAC receiver) or using an additional header to store
> the information contained in the original common header,  but I'd really
> like to know how the people from CMU did this in mac-802_11
> 
> Regards, Sjoerd Janssen.
> 
> 
> 
> 
>