The number of data packet in application and mac layer.

[Kimberry]

Hello.

I'm a new ns3 user and try to develop expanding ring search in aodv routing protocol. This is my configuration :

    Traffic Type : CBR (UDP)
    Packet Size : 512 Bytes
    Data Rate : 2 KiB/s
    Transmission range : 100 m
    Topology : Linear (step = 50)
    Mac Protocol : 802.11
    Mobility : 0 m/s
    Simulation time : 30 s
    Aplication start at 2 s
    Application stop at 20.008 s
    Source node : #0
    Destination node : #7

My problem is when i try to count the number of data packet from source node,  the number of data packet that send from application layer is 2250 packets and not equal to mac and physical layer that send only 2222 packets. I try to trace packet loss and found only 3 packets in  "ns3::WifiRemoteStationManager/MacTxFinalRtsFailed". Can anybody help me to clear this problem?

I will appreciate your suggestions.

Thank you in advance.
Kimberry.

[Kimberry]

Sorry.

 

I try to trace all packet loss and found only 3 packets in  "ns3::WifiRemoteStationManager/MacTxDataFailed".

I will appreciate your suggestions.

Thanks.
Kimberry.

[Tommaso Pecorella]

Hi,

have you checked the IP-level drops ?

In particular, check ns3::ArpCache::Drop, it is the usually forgotten one, and responsible for a large number of drops.

If you want, you can increase the cache queue size, it usually fixes a lot of issues with drops related to burst send.

Hope it helps,

T.

[Kimberry]

Hello Tommaso.

Thank you for your help. It's very helpful. Would you mind if i ask you one more question?

When i choose a farther destination node. In some situation, i found the number of data packet that destination node received from "packet sink" is more than the number of data packet that source node send from application. Could you please give me a suggestion?

Best regards,
Kimberry.

[Tommaso Pecorella]

Hi Kimberly,

most probably they're retransmissions. I'm not an AODV expert, but it could be as well multiple routes.

The point is that the Sink applicatinos blindly counts received packets, without discarding duplicates. By the way, since it does that, you can't be 100% sure that the counters are totally "right". E.g., you could have one lost packet and one duplicate one... it will look like no loss and no duplications.

You can use the UdpClient and UdpServer applications. They do embed a sequence counter in the packets, so you can check if the packet is a duplicate or not.

Cheers,

T.

[Kimberry]

Hi Tommaso,

Thanks so much for your help.

Best regards,
Kimberry