A possible bug in ARP

[Cosmos]

Consider a scenario with 1 AP and 120 stations, each transmitting a maximum of 100,000 bytes. All stations are within range of the AP. 802.11ac is used, with the Ideal Wifi Manager, and data is sent using the BulkSendApplication. Out of the 120 stations, 14 do not send any data. Zero data.

Zero data received from the following IPs:
Node 1: 10.0.0.7
Node 2: 10.0.0.21
Node 3: 10.0.0.28
Node 4: 10.0.0.36
Node 5: 10.0.0.37
Node 6: 10.0.0.42
Node 7: 10.0.0.72
Node 8: 10.0.0.83
Node 9: 10.0.0.85
Node 10: 10.0.0.89
Node 11: 10.0.0.96
Node 12: 10.0.0.116
Node 13: 10.0.0.118
Node 14: 10.0.0.121

Even if the SNR at these nodes was so low that packet reception did not occur, it does not explain how other nodes that were further away from the AP (10.0.0.8 is further away than 10.0.0.7) were able to transfer the data successfully. The topology can be seen in the attached .xml file.

Through the PCAP file, I tried to see why these 14 nodes could not send their data. I realized that these nodes are not broadcasting ARP requests for the AP's IP, even after associating with them. The PCAP file can be found here: https://drive.google.com/open?id=0BxUolX14t897RkZ4dTRXOVJBM3c

Is this a possible bug? Even if collisions did occur, why aren't ARP retransmissions occurring?

Thanks.

P.S: How do I post a bug on bugzilla? I can't seem to make an account.

[Tommaso Pecorella]

Hi,

I think Bugzilla account generation has been disabled because we had a spam attack. i don't know if it has been reactivated. I'll check with the system admins.

About the ARP issue... I so hate when I find this:

1035/2642] Compiling scratch/wifi-tcp.cc

../scratch/wifi-tcp.cc:133:23: error: variable length array of non-POD element type 'ns3::Ipv4Address'

  Ipv4Address NoPacket[nWifi];

                      ^

1 error generated.

Anyway, I checked your script (after fixing it).

There is one more offending line:

  wifiPhy.SetErrorRateModel ("ns3::YansErrorRateModel");

don't ask me why, in the latest ns-3-dev it generates an error. Please check with Sébastien Deronne.

Anyway, after fixing everything, all the nodes are receiving packets.

Summarizing: use ns-3-dev.

Cheers,

T.

[Tom Henderson]

On 07/07/2017 04:01 PM, Tommaso Pecorella wrote:

Hi,

I think Bugzilla account generation has been disabled because we had a spam attack. i don't know if it has been reactivated. I'll check with the system admins.

Please see the front page of Bugzilla: 

For new account creation, email webm...@nsnam.org

- Tom