Is there an easy way to calculate Link Utilization?

[Syd]

Hi Everyone,
I am using the flow monitor to capture network
statistics such as RTT, packet loss ratio etc. Is there some way I can
use it or calculate link utilization (for every link in the network)?
If not, is there some other means I can use to extract this info?
Thanks.

Cheers!
Syd

[posco]

link utilisation = (flow on the link/capacity of the link) in specific
time window.

[Syd]

True. But let me rephrase the question:

How would I determine the flow on a link? Flow monitor provides the
flow on a route. However, this route could contain multiple links.

If this were a smaller network (say 20 nodes), I could probably send a
packet from every source node to every destination and use the
AsciiTraceHelper to get the links on the routes. But with 118 node
network, this may take forever.

Thanks!
Syd

[posco]

what I meant is no way to infer link utilisation from rtt and loss. In
stead, you may try to install trace on every node, e.g.

void FlowTrace::SetupTxTrace(int dev_id, int ith_id)
{
std::ostringstream oss;
oss << "/NodeList/"<<dev_id<<"/DeviceList/"<<ith_id<<"/
$ns3::CsmaNetDevice/TxQueue/Dequeue";
Config::Connect (oss.str (), MakeCallback (&FlowTrace::TxTrace,
this));
}

and then in the callback, capture number of bytes entering the link.

void FlowTrace::TxTrace(std::string context, Ptr<Packet const> packet)
{
total_bytes[dev][iface]+=packet->GetSize();
}

and then compute link utilisation for every specified time window
(e.g. 1s)

void FlowTrace::CalcStatictis()
{
//compute link utilisation
...
...
Simulator::Schedule (Seconds (1), &FlowTrace::CalcStatictis,
this);
}


Hope this helps.

-Posco

[Ali Sydney]

How should I go about determining the values for "dev" and "iface" in "total_bytes[dev][iface]" as defined in the function "TxTrace"?

REF:

Below is a snapshot of the actual script where I'm trying to print the number of bytes on each interface of every node. However, in my call to "CalcStatictis" the total_bytes values are always 0. It appears that "total_bytes[dev][iface]" is not being populated. 

// Install a trace on all pointToPoint interfaces of every node

void NS3ElectricalModel::SetupTxTrace(int dev_id, int ith_id)

{

   std::ostringstream oss;

   oss << "/NodeList/"<<dev_id<<"/DeviceList/"<<ith_id<<"/$ns3::PointToPointNetDevice/TxQueue/Dequeue";

   Config::Connect (oss.str (), MakeCallback (&NS3ElectricalModel::TxTrace, this));

}

// Callback

void NS3ElectricalModel::TxTrace(std::string context, Ptr<Packet const> packet)

{

     total_bytes[devI][ifaceI]+=packet->GetSize();

}

void NS3ElectricalModel::CalcStatictis()

{

   //compute link utilisation

int node, eth;

node=eth=0;

// For every node in the node container "Nodes_Tier3"

  for (NodeContainer::Iterator n = Nodes_Tier3.Begin (); n != Nodes_Tier3.End (); ++n) 

    {

      Ptr<Node> n = *node;

     

      // For every interface on node "n"

      for (uint32_t eth = 0; eth < n->GetNDevices (); ++eth)

        {

            // Print out the number of bytes

           std::cout<<"Interface " << "\t" << eth << "\t" << "bytes" << total_bytes[node][eth]

          eth++;

        }

     node++;

     eth=0;

    }

   Simulator::Schedule (Seconds (1), &NS3ElectricalModel::CalcStatictis,this);

}

-Syd

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[Syd]

In my previous post, I said "total_bytes[dev][iface]" was not being
populated. Actually, I manually set dev=0 and iface=0 and so
total_bytes[0][0] was being populated. However, can you help me figure
out how to dynamically set "dev" and "iface"?

[posco]

dev = i-th node.
iface = j-th devices in i-th node.

e.g.

for(int i=0; i<(int)c.GetN(); i++)
{
for(int j=1; j<(int)c.Get(i)->GetNDevices(); j++)
{
SetupTxTrace(i,j);
}
}

-Posco

[Ali Sydney]

I do something similar when calling  "SetupTxTrace" as shown in the REF. However, in the "TxTrace" function, how are the values for "dev" and "iface" passed to this function (i.e. TxTrace)? Does the "Connect" call from "SetupTxTrace" implicitly pass the values for "dev" and "iface" to TxTrace? 

Config::Connect (oss.str (), MakeCallback (&NS3ElectricalModel::TxTrace,
 this));

REF:

// IN MAIN FUNCTION

...

  NetDeviceContainer devs;

  for (NodeContainer::Iterator i = Nodes_Tier3.Begin (); i != Nodes_Tier3.End (); ++i)

    {

      Ptr<Node> node = *i;

      for (uint32_t j = 0; j < node->GetNDevices (); ++j)

        {

          devs.Add (node->GetDevice (j));

        }

    }

  // Setup trace on all devices 

  for (NetDeviceContainer::Iterator i = devs.Begin (); i != devs.End (); ++i)

    {

      Ptr<NetDevice> dev = *i;

      NS3ElectricalModel::SetupTxTrace( dev->GetNode ()->GetId (), dev->GetIfIndex ());

     }

 NS3ElectricalModel::CalcStatictis();

...

}

//END OF MAIN FUNCTION

 // Install a trace on all pointToPoint interfaces of every node
void 

NS3ElectricalModel::SetupTxTrace(int dev_id, int ith_id)
 {
    std::ostringstream oss;
    oss <<
 "/NodeList/"<<dev_id<<"/DeviceList/"<<ith_id<<"/$ns3::PointToPointNetDevice /TxQueue/Dequeue";
    Config::Connect (oss.str (), MakeCallback (&NS3ElectricalModel::TxTrace,
 this));
 }

 // Callback
 void 

NS3ElectricalModel::TxTrace(std::string context, Ptr<Packet const>
 packet)
 {

      total_bytes[dev][iface]+=packet->GetSize();
 }

void 

[Syd]

From your previous post, that is correct (i.e. passing the node and
its corresponding device to to SetupTxTrace): and I have done
something similar (as shown in the previous post).

But I was referring to to the values of "dev" and "iface" in the
function "TxTrace". Which function passes these values to "TxTrace"?
It appears that "SetupTxTrace" makes a "Connect" call to "TxTrace".
Are the values for "dev" and "iface" implicitly passed? Or do I have
to modify the connect call as follows?

Config::Connect (oss.str (), MakeCallback

(&NS3ElectricalModel::TxTrace,this, dev_id, ith_id));

-Syd

[posco]

NS3ElectricalModel::TxTrace(std::string context, Ptr<Packet
const>packet)
{

//"dev" and "iface" are incorporated in context string, so you'll need
to parse the string for retrieving them

[Syd]

Hi Posco,
Everything works perfectly! Thanks a million!

Cheers!
Syd

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