TapBridge: issues with Access Point wifi network

[Mauro Sardara]

Hi there,

I'm meeting some problems with the TapBridge Device. I'm trying to build a very simple netwotk:

- 2 Linux container

- 1 Access Point

- 2 Simulated Hosts

Here is the code:

 std::string mode = "UseLocal";
  std::string tapName = "tap-left";


  CommandLine cmd;
  cmd.AddValue ("mode", "Mode setting of TapBridge", mode);
  cmd.AddValue ("tapName", "Name of the OS tap device", tapName);
  cmd.Parse (argc, argv);


  GlobalValue::Bind ("SimulatorImplementationType", StringValue ("ns3::RealtimeSimulatorImpl"));
  GlobalValue::Bind ("ChecksumEnabled", BooleanValue (true));


  //
  // The topology has a Wifi network of four nodes on the left side.  We'll make
  // node zero the AP and have the other three will be the STAs.
  //
  NodeContainer nodesLeft;
  nodesLeft.Create (4);


  YansWifiPhyHelper wifiPhy = YansWifiPhyHelper::Default ();
  YansWifiChannelHelper wifiChannel = YansWifiChannelHelper::Default ();
  wifiPhy.SetChannel (wifiChannel.Create ());


  Ssid ssid = Ssid ("left");
  WifiHelper wifi = WifiHelper::Default ();
  NqosWifiMacHelper wifiMac = NqosWifiMacHelper::Default ();
  wifi.SetRemoteStationManager ("ns3::ArfWifiManager");


  wifiMac.SetType ("ns3::ApWifiMac",
                   "Ssid", SsidValue (ssid));
  NetDeviceContainer devicesLeft = wifi.Install (wifiPhy, wifiMac, nodesLeft.Get (0));




  wifiMac.SetType ("ns3::StaWifiMac",
                   "Ssid", SsidValue (ssid),
                   "ActiveProbing", BooleanValue (false));
  devicesLeft.Add (wifi.Install (wifiPhy, wifiMac, NodeContainer (nodesLeft.Get (1), nodesLeft.Get (2), nodesLeft.Get (3))));


  MobilityHelper mobility;
  mobility.Install (nodesLeft);


  InternetStackHelper internetLeft;
  internetLeft.Install (nodesLeft);


  Ipv4AddressHelper ipv4Left;
  ipv4Left.SetBase ("10.0.0.0", "255.255.255.0");
  Ipv4InterfaceContainer interfacesLeft = ipv4Left.Assign (devicesLeft);


  TapBridgeHelper tapBridge;
  tapBridge.SetAttribute ("Mode", StringValue (mode));
  tapBridge.SetAttribute ("DeviceName", StringValue (tapName));
  tapBridge.Install (nodesLeft.Get (0), devicesLeft.Get (0));

  tapBridge.SetAttribute ("DeviceName", StringValue ("tap-right"));
  tapBridge.Install (nodesLeft.Get (1), devicesLeft.Get (1));
  //
  // Run the simulation for ten minutes to give the user time to play around
  //
  Simulator::Stop (Seconds (600.));
  Simulator::Run ();
  Simulator::Destroy ();

I took this code from a your example.

Here is the list of things I tried:

- When I connect with one container to the AP node, I'm able to ping all the virtual nodes

- If I connect the linux container on a virtual node (so a Ghost node), I'm not able to ping the other virtual nodes

- If I connect with a Lxc to the AP, I'm able to ping the other virtual hosts but not another virtual container connected to a ghost

With the ad hoc topology everything is working well, I do not understand why with an access point the interaction does not work.

I wait for your help as soon as possible.

Thank you in advance,

Mauro.

[Mauro Sardara]

So, nobody in the community could help me? :(

[Tommaso Pecorella]

Hi,

sadly my current setup doesn't allow me to run this code. I need the work computers and... well, it's holidays.

Moreover, mind to attach the full script and tell us exactly the commands you used (and are either working or not working) ?

Thanks,

T.

[Mauro Sardara]

Hi Tommaso!

I'm following this tutorial:

https://www.nsnam.org/wiki/HOWTO_Use_Linux_Containers_to_set_up_virtual_networks

Rapidly, you have to do the following operations:

#Create bridge and tap net devices

sudo brctl addbr br-left
sudo brctl addbr br-right

sudo tunctl -t tap-left
sudo tunctl -t tap-right

sudo ifconfig tap-left 0.0.0.0 promisc up
sudo ifconfig tap-right 0.0.0.0 promisc up

sudo brctl addif br-left tap-left
sudo ifconfig br-left up
sudo brctl addif br-right tap-right
sudo ifconfig br-right up

cd /proc/sys/net/bridge

sudo -s

for f in bridge-nf-*; do echo 0 > $f; done
exit

cd -

# Create linux containers with conf file in ns3-allinone/src/tap-bridge/examples

sudo lxc-create -n left -f lxc-left.conf

sudo lxc-create -n right -f lxc-right.conf

sudo lxc-start -n left /bin/bash
sudo lxc-start -n right /bin/bash

After this, you have 2 linux containers connected to a tap interface through a linux bridge.

Now, you can try the example script ns3-allinone/src/tap-bridge/examples/tap-wifi-virtual-machine.cc

This script, connects the 2 linux container with an emulated AD-HOC wifi network. And with this network, all works well, I can create an arbitrary number of linux container, they are always able to talk together through the wifi.

The problem happens when I try to connect the containers through an emulated Wi-Fi network with an access point.

The linux containers are not able to communicate, and I can only ping emulated hosts.

You can try the following script:

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

//

// This is an illustration of how one could use virtualization techniques to

// allow running applications on virtual machines talking over simulated

// networks.

//

// The actual steps required to configure the virtual machines can be rather

// involved, so we don't go into that here.  Please have a look at one of

// our HOWTOs on the nsnam wiki for more details about how to get the 

// system confgured.  For an example, have a look at "HOWTO Use Linux 

// Containers to set up virtual networks" which uses this code as an 

// example.

//

// The configuration you are after is explained in great detail in the 

// HOWTO, but looks like the following:

//

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

//  | virtual  |                           | virtual  |

//  |  Linux   |                           |  Linux   |

//  |   Host   |                           |   Host   |

//  |          |                           |          |

//  |   eth0   |                           |   eth0   |

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

//       |                                      |

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

//  |  Linux   |                           |  Linux   |

//  |  Bridge  |                           |  Bridge  |

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

//       |                                      |

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

//  | "tap-" |                       | "tap-right" |

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

//       |           n0            n1           |

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

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

//               | bridge |    | bridge |

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

//               |  wifi  |    |  wifi  |

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

//                   |             |

//                 ((*))         ((*))

//

//                       Wifi LAN

//

//                        ((*))

//                          |

//                     +--------+

//                     |  wifi  |

//                     +--------+

//                     | access |

//                     |  point |

//                     +--------+

//

#include <iostream>

#include <fstream>

#include "ns3/core-module.h"

#include "ns3/network-module.h"

#include "ns3/mobility-module.h"

#include "ns3/point-to-point-module.h"

#include "ns3/wifi-module.h"

#include "ns3/internet-module.h"

#include "ns3/csma-module.h"

#include "ns3/applications-module.h"

#include "ns3/ipv4-global-routing-helper.h"

#include "ns3/tap-bridge-module.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("TapWifiVirtualMachineExample");

int 

main (int argc, char *argv[])

{

  //

  // We are interacting with the outside, real, world.  This means we have to 

  // interact in real-time and therefore means we have to use the real-time

  // simulator and take the time to calculate checksums.

  //

  GlobalValue::Bind ("SimulatorImplementationType", StringValue ("ns3::RealtimeSimulatorImpl"));

  GlobalValue::Bind ("ChecksumEnabled", BooleanValue (true));

  std::string mode = "UseLocal";

  std::string tapName = "tap-left";

  CommandLine cmd;

  cmd.AddValue ("mode", "Mode setting of TapBridge", mode);

  cmd.AddValue ("tapName", "Name of the OS tap device", tapName);

  cmd.Parse (argc, argv);

  //

  // The topology has a Wifi network of four nodes on the  side.  We'll make

  // node zero the AP and have the other three will be the STAs.

  //

  NodeContainer nodes;

  nodes.Create (4);

  YansWifiPhyHelper wifiPhy = YansWifiPhyHelper::Default ();

  YansWifiChannelHelper wifiChannel = YansWifiChannelHelper::Default ();

  wifiPhy.SetChannel (wifiChannel.Create ());

  Ssid ssid = Ssid ("WiFi");

  WifiHelper wifi = WifiHelper::Default ();

  NqosWifiMacHelper wifiMac = NqosWifiMacHelper::Default ();

  wifi.SetRemoteStationManager ("ns3::ArfWifiManager");

  wifiMac.SetType ("ns3::ApWifiMac",

                   "Ssid", SsidValue (ssid));

  NetDeviceContainer devices = wifi.Install (wifiPhy, wifiMac, nodes.Get (0));

  wifiMac.SetType ("ns3::StaWifiMac",

                   "Ssid", SsidValue (ssid),

                   "ActiveProbing", BooleanValue (false));

  devices.Add (wifi.Install (wifiPhy, wifiMac, NodeContainer (nodes.Get (1), nodes.Get (2), nodes.Get (3))));

  MobilityHelper mobility;

  mobility.Install (nodes);

  InternetStackHelper internet;

  internet.Install (nodes);

  Ipv4AddressHelper ipv4;

  ipv4.SetBase ("10.0.0.0", "255.255.255.0");

  Ipv4InterfaceContainer interfaces = ipv4.Assign (devices);

  TapBridgeHelper tapBridge;

  tapBridge.SetAttribute ("Mode", StringValue (mode));

  tapBridge.SetAttribute ("DeviceName", StringValue (tapName));

  tapBridge.Install (nodes.Get (1), devices.Get (1));

  tapBridge.SetAttribute ("DeviceName", StringValue ("tap-right"));

  tapBridge.Install (nodes.Get (2), devices.Get (2));

  //

  // Run the simulation for ten minutes to give the user time to play around

  //

  Simulator::Stop (Seconds (600.));

  Simulator::Run ();

  Simulator::Destroy ();

}

Is there an error in this script? Maybe I'm missing some things, I don't know.

Thank you in advance for the response.

Kind Regards,

Mauro Sardara.

[Mauro Sardara]

Any suggestion?

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