point-to-point upload and download bottlneck

[Hiba Yousef]

Dear all,

At first, thanks for having this helpful group!

I have a question regarding the point-to-point liink, I read that it is symmetric link,
But when I used it for uploading and downloading I got a bottleneck issue.

I used very simple point-to-poitnt configuration:

 // Default Network Topology

 //                                                                          emu{i}

 //                                                                                |

 //                                                                         +------------+

 //                                                                        | tap-bridge |

 //     +--------+                                                     +------------+

 //     | Server |                                                 | Csma ghost |

 //     +--------+                                                     +------------+

 //         |                                                                       |2

 //         |                                                                 10.1.{i}.0

 //         |                                                                        | 1

 //         |                                                              +--------------+

 //      emu0                                                        | Csma ghost |

 //   +----------+                                                      +------------+

 //   |  tap       |                                                       |   p2p      |

 //   | bridge   |                                                      +------------+

 //   +----------+                +---------+ 1     10.3.{i}.0      2 |

 //   | CSMA0 |                 |  p2p    | -------------------------+

 //    +----------+               +---------+ 1

 //          |                        |CSMA0 |

 //          |                        +---------+

 //          |0     10.1.100.0    5 |

 //          +-------------------------+

 //

I used  the following configuration :

NodeContainer outputNodes,

                p2ppeer{i},

                csmapeer{i};

  outputNodes.Create (noutputNodes);

  p2ppeer{i}.Add( outputNodes.Get (0));

  p2ppeer{i}.Create (1);

  csmapeer{i}.Add( p2ppeer{i}.Get (1));

  csmapeer{i}.Create (1);

  NetDeviceContainer outputDevices,

                     p2ppeer{i}Devices,

                     csmapeer{i}Devices;

  // CSMA channel

  CsmaHelper csma;

  csma.SetChannelAttribute ("DataRate", StringValue ("1Gbps"));

  csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (1)));

  outputDevices = csma.Install (outputNodes);

  csmapeer{i}Devices =  csma.Install (csmapeer{i});

  Ptr<NetDevice> devicepeer{i} = outputDevices.Get (0);

  devicepeer{i}->SetAddress (Mac48Address ("aa:ff:00:00:00:{I}"));

  // point-to-point channels

  PointToPointHelper pointToPoint;

  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("2Mbps"));

  pointToPoint.SetChannelAttribute ("Delay", StringValue ("1ms"));

  p2ppeer{i}Devices = pointToPoint.Install (p2ppeer{i});

 

 

Whenever I start uploading and downloading at the same time, the download bandwidth is dropped, and when I stop uplading the bandwidth goes back to 2Mbps

Do you think the point to point is a bottleneck ? if so I was thinking it might be a queue issue but I don't really know how to solve it  

(I can not upload the images or any files looks like there is a problem )

Thanks in advance for your time and help !!

 

[Jared Dulmage]

Maybe first see if the P2P net supports full-duplex TX.  I didn't see anything in the code that would suggest it wasn't.  But it seems simple enough to make just a P2P network with a couple nodes and have them transmit to each other.

Jared.

[Hiba Yousef]

Thanks for your answer,

In fact I solved this issue using different queue,
For some reason the default queue of p2p (fastcodel) was giving huge RTTs when I tried to ping, so I changes to CODEL queus and enabled BQL, this gave lower RTTs and full duplexity.

[Tom Henderson]

On 10/8/19 6:15 AM, Hiba Yousef wrote:
> Thanks for your answer,
>
> In fact I solved this issue using different queue,
> For some reason the default queue of p2p (fastcodel) was giving huge
> RTTs when I tried to ping, so I changes to CODEL queus and enabled BQL,
> this gave lower RTTs and full duplexity.
>

Which version of ns-3 are you using? The current default for p2p is
FQ-CoDel which has BQL and CoDel as part of it, so I am surprised that
changing to plain CoDel and BQL makes any difference. In older versions
of ns-3, however, the default queue configuration is different.

- Tom

[Hiba Yousef]

Then that's ally surprising !
I am using the 3.29 version. I also changed the queue maxSize to 25 packets. then added BQL where I got the best performance !

Hiba

[Tom Henderson]

On 10/8/19 6:49 AM, Hiba Yousef wrote:

Then that's ally surprising !
I am using the 3.29 version. I also changed the queue maxSize to 25 packets. then added BQL where I got the best performance !

OK, with ns-3.30, FqCoDel with BQL is now the default.

- Tom