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# Network Simulation: Labwork 2
Consider the ns-3 example `tutorial/first.cc`.
## Logging
Enable LOG_LEVEL_FUNCTION for UdpEchoServer and UdpEchoClient:
```diff
diff --git a/examples/tutorial/first.cc b/examples/tutorial/first.cc
index f68eb6a8e..38a277a69 100644
--- a/examples/tutorial/first.cc
+++ b/examples/tutorial/first.cc
@@ -38,8 +38,8 @@ main (int argc, char *argv[])
cmd.Parse (argc, argv);
Time::SetResolution (Time::NS);
- LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
- LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);
+ LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_FUNCTION);
+ LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_FUNCTION);
NodeContainer nodes;
nodes.Create (2);
```
List out functions used by the two classes:
```console
$ waf --run first.cc 2>&1 | grep UdpEcho
UdpEchoServerApplication:UdpEchoServer(0x55d1742cdd30)
UdpEchoClientApplication:UdpEchoClient(0x55d1742f4820)
UdpEchoClientApplication:SetDataSize(0x55d1742f4820, 1024)
UdpEchoServerApplication:StartApplication(0x55d1742cdd30)
UdpEchoClientApplication:StartApplication(0x55d1742f4820)
UdpEchoClientApplication:ScheduleTransmit(0x55d1742f4820, +0ns)
UdpEchoClientApplication:Send(0x55d1742f4820)
UdpEchoServerApplication:HandleRead(0x55d1742cdd30, 0x55d1742bdcf0)
UdpEchoClientApplication:HandleRead(0x55d1742f4820, 0x55d1742ba420)
UdpEchoClientApplication:StopApplication(0x55d1742f4820)
UdpEchoServerApplication:StopApplication(0x55d1742cdd30)
UdpEchoClientApplication:DoDispose(0x55d1742f4820)
UdpEchoServerApplication:DoDispose(0x55d1742cdd30)
UdpEchoClientApplication:~UdpEchoClient(0x55d1742f4820)
UdpEchoServerApplication:~UdpEchoServer(0x55d1742cdd30)
```
## Attributes
1. Set up data rate of 10 Mbps and propagation delay of 10 ms:
```diff
diff --git a/examples/tutorial/first.cc b/examples/tutorial/first.cc
index f68eb6a8e..973b6fc14 100644
--- a/examples/tutorial/first.cc
+++ b/examples/tutorial/first.cc
@@ -45,8 +45,8 @@ main (int argc, char *argv[])
nodes.Create (2);
PointToPointHelper pointToPoint;
- pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
- pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
+ pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("10Mbps"));
+ pointToPoint.SetChannelAttribute ("Delay", StringValue ("10ms"));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
```
2. Run the updated script and compute the average delay of received packets
at the server and client:
```console
$ waf --run first.cc
At time +2s client sent 1024 bytes to 10.1.1.2 port 9
At time +2.01084s server received 1024 bytes from 10.1.1.1 port 49153
At time +2.01084s server sent 1024 bytes to 10.1.1.1 port 49153
At time +2.02169s client received 1024 bytes from 10.1.1.2 port 9
```
3. Compare the average delay of received packets at server and client
between device and channel attributes of (5 Mbps, 1 ms) and (10 Mbps, 10 ms)
with the number of packets set to 100:
```diff
diff --git a/examples/tutorial/first.cc b/examples/tutorial/first.cc
index f68eb6a8e..62169f460 100644
--- a/examples/tutorial/first.cc
+++ b/examples/tutorial/first.cc
@@ -66,8 +66,8 @@ main (int argc, char *argv[])
serverApps.Stop (Seconds (10.0));
UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9);
- echoClient.SetAttribute ("MaxPackets", UintegerValue (1));
- echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.0)));
+ echoClient.SetAttribute ("MaxPackets", UintegerValue (100));
+ echoClient.SetAttribute ("Interval", TimeValue (Seconds (0.0)));
echoClient.SetAttribute ("PacketSize", UintegerValue (1024));
ApplicationContainer clientApps = echoClient.Install (nodes.Get (0));
```
To make best use of the bandwidth, we send all packets at the same time.
The average delay of received packets is calculated as follows:
```bash
waf --run first.cc 2>&1 |
sed -rn 's/.*\+2([.0-9]+)s client received .*/\1/p' |
awk '{sum+=$1} END {print "Packet delivery ratio =", NR,
"%\nAverage delay =", sum/NR/2*1000, "ms"}'
```
For attributes of (5 Mbps, 1 ms), we get:
Packet delivery ratio = 100 %
Average delay = 44.4248 ms
For attributes of (10 Mbps, 10 ms), we get:
Packet delivery ratio = 100 %
Average delay = 31.7124 ms
In short, the latter has lower *mean* latency.
## Packet Traces Capturing
### ASCII Tracing
We revert to the initial configuration (10 Mbps rate, 10 ms delay)
and apply the following patch:
```diff
diff --git a/examples/tutorial/first.cc b/examples/tutorial/first.cc
index f68eb6a8e..a63f43835 100644
--- a/examples/tutorial/first.cc
+++ b/examples/tutorial/first.cc
@@ -74,6 +74,9 @@ main (int argc, char *argv[])
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
+ AsciiTraceHelper ascii;
+ pointToPoint.EnableAsciiAll (ascii.CreateFileStream ("first.tr"));
+
Simulator::Run ();
Simulator::Destroy ();
return 0;
```
The content of `first.tr` is pasted below:
+ 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
- 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Dequeue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
r 2.01084 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/MacRx ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
+ 2.01084 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)
- 2.01084 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Dequeue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)
r 2.02169 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/MacRx ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)
It can be seen that the total packet size is 1052 bytes
and thus the delay for packet receival can be computed as
1052 B / 10 Mbps + 10 ms = 0.8416 ms + 10 ms = 10.8416 ms
which matches the simulated figures.
### PCAP Tracing
The following patch is used for PCAP tracing:
```diff
diff --git a/examples/tutorial/first.cc b/examples/tutorial/first.cc
index f68eb6a8e..1f5a7fa08 100644
--- a/examples/tutorial/first.cc
+++ b/examples/tutorial/first.cc
@@ -74,6 +74,8 @@ main (int argc, char *argv[])
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
+ pointToPoint.EnablePcapAll ("first");
+
Simulator::Run ();
Simulator::Destroy ();
return 0;
```
## Results
The result of each simulation has been detailed in the respective section.
|
