[ndnSIM] [EXT] Can we access ns3 packet tags in forwarder.cc

Atif Rehman atif_r at outlook.com
Thu Jun 10 17:02:46 PDT 2021

Hi Sonia,

Just out of curiosity, why do you need physical/MAC layer parameter at network layer. Specifically, in SNR case, do we really need that at network layer or is it even possible that we can fetch SNR value at network layer? In the later case, I might be wrong but I don’t think SNR value will be retained at network layer, at least in the default implementation.

So here is the rationale with an example. Node 1 received a packet let say through wireless medium in this case, and at MAC layer the error in packet (frame) is calculated. Now MAC layer encountered that the SNR is high and the packet has to be fetched again from the forwarding node because there is no other way to reconstruct the original packet. In this case, the MAC layer will not forward the packet to the upper layer but rather wait for the forwarding node to send the packet again.

You may ask why the MAC layer shouldn’t send the packet to the network layer, and for that the rationale is,  if the received packet has many erroneous bits then it is useless to further process the packet.

Finally, if the packet is correctly received, it will be sent to the network layer and at this time there will be either no or extremely small SNR.

Concluding all this, I would say that, may be you will be able to fetch the SNR tag value using Junxiao solution but when you will extract its value, it will be 0 in most of the cases.

Please do share your experience once you done with the experiments. Thanks


Muhammad Atif Ur Rehman ( Ph.D. Candidate )

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