Mac Retransmission ad MacDrop

[Matteo Danieletto]

Hi all,

I am interesting, for some simulations, to collect the total number of packet retransmission at Mac layer during a run. 

I found the point where the Mac retransmissions are counted, 

My question is:

is there a better way (tracing) than modify the ns3 core?

The second question 

When 

• MacRxDrop: A packet has been dropped in the MAC layer after it has been passed up from the physical layer.

succeed? 

Thank you

Matteo

[Sebastien Deronne]

1/ Maybe those traces could help:
 
    MacTxDataFailed: this is triggered each time a transmission fails, regardless there is a retransmission that will be scheduled.
  
    MacTxFinalDataFailed: this is triggered if a retransmissions fails and that no retransmission is scheduled (packet is dropped).

I believe by combining those traces you could get what you want.

2/ What is your question? This is not clear.

[Matteo Danieletto]

Hi Sebastian 

thank you to replay me.

Yes I think that combining both traces I can obtain the measurement I want. 

For the second question, when a packet is dropped? I understood the packet comes from the PHY layer and MAC layer drop it, but why the MAC layer drop packet? The MAC queue is full and/or other events?

Thank you

Matteo

[Tommaso Pecorella]

LMLATCFY (Let Me Look At The Code or You).

StaWifiMac::Receive (Ptr<Packet> packet, const WifiMacHeader *hdr)
...
      NS_LOG_LOGIC ("packet is not for us");
      NotifyRxDrop (packet);
...
          NS_LOG_LOGIC ("Received data frame while not associated: ignore");
          NotifyRxDrop (packet);
...
          NS_LOG_LOGIC ("Received data frame not from the DS: ignore");
          NotifyRxDrop (packet);
...
          NS_LOG_LOGIC ("Received data frame not from the BSS we are associated with: ignore");
          NotifyRxDrop (packet);
...
      //This is a frame aimed at an AP, so we can safely ignore it.
      NotifyRxDrop (packet);

ApWifiMac::Receive (Ptr<Packet> packet, const WifiMacHeader *hdr)
...
          //this is an AP-to-AP frame
          //we ignore for now.
          NotifyRxDrop (packet);
...
          //we can ignore these frames since
          //they are not targeted at the AP
          NotifyRxDrop (packet);

Suggestion: a good IDE (e.g., Eclipse, NetBeans, etc.) can do wonderful tricks.

T.

PS: no, there's no Rx queue at MAC level. There's a Tx queue only, Rx packets are immediately delivered to upper layers.

[Matteo Danieletto]

Thank you.

I have small final question about the trace.

To call the trace MacTxFinalDataFailed and MacTxDataFailed I used the following path:

/NodeList/*/DeviceList/*/RemoteStationManager/MacTxFinalDataFailed and MacTxDataFailed

and it works using Config::Connect

But, before to achieve that path I wrote with WifiRemoteStationManager instead to RemoteStationManager  and the functions weren't triggered.

Do you know why?

Thank you

Matteo

[Konstantinos]

Hi Matteo,

I will refer you the the NS-3 API for WifiRemoteStationManager 

https://www.nsnam.org/docs/doxygen/classns3_1_1_wifi_remote_station_manager.html

and more specifically, the point where the config path is given

ns3::WifiRemoteStationManager is accessible through the following paths with Config::Set and Config::Connect:

• "/NodeList/[i]/DeviceList/[i]/$ns3::WifiNetDevice/RemoteStationManager"

This, will answer your question.