ndnSIM

• I plan on trying to port ndn-udp-face first since it's simpler
• I'll use ndn-net-device-face as a baseline

Questions:

• To receive data, should I be registering a receive callback with the underlying transport mechanism(ns3 socket?)
• What is the point of TcpBoundaryHeader in ndn-tcp-face? Is it used for debugging or do we actually need to add an extra header ? (https://github.com/NDN-Routing/ndnSIM/blob/master-v1/plugins/ip-faces/ndn-tcp-face.cc)

Hello Steven,

1) To my understanding, the answer is yes, you will need to use the ns3 socket class, but you will have to replace the existing Face class with the Face class of NFD and, in general, overload the methods of the nfd::Face class. For example, the RegisterProtocolHandlers and UnRegisterProtocolHandlers methods do not exist anymore.
2) To my understanding again by looking at the source code, Alex has made some tricks (or "magic" as he likes to call it :)) and actually sends two NS3 packets. The first one contains the segment length at its header and the second one is the actual TCP segment:

https://github.com/NDN-Routing/ndnSIM/blob/master-v1/plugins/ip-faces/ndn-tcp-face.cc#L172-L177

I guess that he did that to make the sending the receiving process easier.

@Alex: feel free to correct me, if I have said something wrong. Actually, I have not worked enough with these TCP, IP and UDP faces in order to be 100% sure that the things I have said are fully correct.

• To receive data, should I be registering a receive callback with the underlying transport mechanism(ns3 socket?)
  Yes, though I don't really understand this question. With TCP face, you need to communicate through tcp tunnel, not raw network interface like in NetDeviceFace.

• What is the point of TcpBoundaryHeader in ndn-tcp-face? Is it used for debugging or do we actually need to add an extra header ?
  (https://github.com/NDN-Routing/ndnSIM/blob/master-v1/plugins/ip-faces/ndn-tcp-face.cc)
  This could be my question for you in cs118 :) This additional header was useful with old packet format (as there was no indication about message length in the packet format itself). With new packet format, it is no longer needed.

I noticed NetDeviceFace increments a FwHopCountTag before sending a packet. Should the Udp/Tcp Faces also increment the hop count? https://github.com/NDN-Routing/ndnSIM/blob/master/model/ndn-net-device-face.cpp#L84-L87

Yes. FwHopCount needs to be increased.

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