To simulate HTTP and HTTPS projects using NS2 that needs modeling how web traffic flows among a client and a server. Because NS2 doesn’t natively support HTTPS (which involves encryption), HTTPS behaviour can be estimated by replicating encryption overhead, even though HTTP traffic can be mimicked using TCP connections. Both protocols usually operate over the TCP/IP stack.
In this guide, we will indicate how to simulate HTTP traffic and approximate HTTPS traffic by inserting encryption-related overheads.
Steps to Simulate HTTP HTTPS Projects in NS2
- Install NS2
- We can download and install NS2 from the official NS2 website.
- Make sure that necessary dependencies such as Tcl/Tk, OTcl, and NAM (Network Animator) are installed for running simulations and visualizing outcomes.
- Understand HTTP and HTTPS Concepts
- HTTP (Hypertext Transfer Protocol): A protocol utilized to fetch resources such as HTML documents over the web. It runs over TCP (port 80).
- HTTPS (HTTP Secure): An extension of HTTP in which the communication is encrypted using SSL/TLS, normally running over TCP (port 443). In NS2, encryption can be replicated by inserting delays to replicate encryption/decryption time.
- Define the Network Topology
Initially, we make a network topology in which the client (e.g., a browser) connects to a web server over TCP. We can configure intermediate routers to replicate a real-world network environment.
Example OTcl Code for HTTP/HTTPS Topology:
# Create a simulator instance
set ns [new Simulator]
# Define the topology (e.g., a client-server setup)
set topo [new Topography]
$topo load_flatgrid 1000 1000 ;# Define the area (1000×1000 meters)
# Create nodes (client and server)
set client [$ns node]
set server [$ns node]
# Set up routers between client and server (optional)
set router1 [$ns node]
set router2 [$ns node]
# Set up links between nodes (with bandwidth and delay characteristics)
$ns duplex-link $client $router1 10Mb 10ms DropTail
$ns duplex-link $router1 $router2 10Mb 20ms DropTail
$ns duplex-link $router2 $server 10Mb 10ms DropTail
In this example:
- Client: Denotes a web browser requesting data from a server.
- Server: Signifies a web server reacting to the client’s HTTP/HTTPS requests.
- Links among the nodes are set up with particular bandwidth and delay.
- Configure TCP Agents
Since both HTTP and HTTPS run across TCP we will require to set up TCP agents at the client and server nodes.
Example: Setting Up TCP Agents for HTTP/HTTPS Traffic
# Create a TCP agent at the client (for HTTP/HTTPS requests)
set tcp_client [new Agent/TCP]
$tcp_client set class_ 2 ;# TCP Reno by default
$ns attach-agent $client $tcp_client
# Create a TCP sink at the server (to receive HTTP/HTTPS traffic)
set tcp_sink [new Agent/TCPSink]
$ns attach-agent $server $tcp_sink
# Connect the TCP agent and the TCP sink
$ns connect $tcp_client $tcp_sink
In this example:
- TCP agent is made at the client to mimic HTTP/HTTPS traffic.
- TCP sink is made at the server to receive traffic.
- Simulate HTTP Traffic
We can be used an FTP application within NS2 to replicate bulk data transfer over a TCP connection that estimates HTTP traffic. For a more HTTP-specific scenario, we can be replicated several, shorter TCP connections.
Example: HTTP Traffic Using FTP Application
# Create an FTP application attached to the TCP client
set ftp [new Application/FTP]
$ftp attach-agent $tcp_client
# Start the FTP (HTTP-like) traffic at time 1.0 seconds
$ns at 1.0 “$ftp start”
This replicates a large data transfer, same to a file download through HTTP.
- Simulate HTTPS Traffic (with Encryption Overhead)
To replicate HTTPS, insert delays to account for encryption/decryption overhead. We can estimate the time needed for encryption by inserting an additional delay in the packet transmission process.
Example: Adding Encryption Overhead for HTTPS Simulation
# Function to simulate encryption/decryption delay in HTTPS
proc simulate_encryption_delay {pkt} {
global ns
set delay [expr rand() * 10] ;# Simulate random encryption delay (e.g., 0-10 ms)
$ns at [$ns now + $delay] “forward_packet $pkt”
}
# Function to simulate packet forwarding after encryption
proc forward_packet {pkt} {
puts “Packet forwarded after encryption”
# Normally forward the packet here
}
# Attach the encryption delay to packet transmission
$ns at 1.0 “simulate_encryption_delay packet1”
In this example:
- The simulate_encryption_delay function launches a random delay to replicate the time spent encrypting and decrypting traffic, simulating HTTPS communication.
- Run the Simulation
We can save OTcl script as http_https_simulation.tcl and run the simulation using NS2:
ns http_https_simulation.tcl
- Analyze the Results
The simulator NS2 generates trace files, which log all network events, containing packet transmission, delays, acknowledgments, and losses. We can investigate these trace files to estimate key performance parameters like:
- Throughput: The total amount of data sent among the client and server.
- Latency: The time taken to establish a connection and transfer data that will be higher in HTTPS because of encryption overhead.
- Packet Loss: The amount of dropped packets because of congestion or other factors.
Example: Analyze Trace Files Using Awk
awk -f analyze_trace.awk http_https_simulation.tr
- Visualize the Simulation Using NAM
We can be used Network Animator (NAM) to envision the communication among the client and server. NAM will indicate packet transmissions and routing via intermediate nodes (if any).
nam http_https_simulation.nam
- Advanced HTTP/HTTPS Features to Simulate
We can expand the HTTP/HTTPS simulation to contain more advanced aspects:
- Multiple HTTP Requests: Mimic several short TCP connections to simulate how web pages load resources like images, CSS, and JavaScript files.
- Traffic Types: Replicate distinct kinds of web traffic, like video streaming, file downloads, or small web page requests.
- HTTPS with Realistic Delays: We can use more complex encryption overhead models to replicate SSL/TLS handshakes and encryption for HTTPS.
- Congestion and Loss: Mimic how HTTP and HTTPS manage the network congestion and packet loss.
- HTTPS with TCP Variants: Test with distinct TCP variants (e.g., Reno, NewReno, Sack) to observe how they influence HTTPS traffic performance.
Example Simulation Script Outline for HTTP/HTTPS
# HTTP/HTTPS Simulation Script using NS2
set ns [new Simulator]
set topo [new Topography]
$topo load_flatgrid 1000 1000 ;# Define the topology area
# Create client and server nodes
set client [$ns node]
set server [$ns node]
# Create routers between client and server
set router1 [$ns node]
set router2 [$ns node]
# Set up links between nodes (with bandwidth and delay)
$ns duplex-link $client $router1 10Mb 10ms DropTail
$ns duplex-link $router1 $router2 10Mb 20ms DropTail
$ns duplex-link $router2 $server 10Mb 10ms DropTail
# Create a TCP agent at the client
set tcp_client [new Agent/TCP]
$tcp_client set class_ 2 ;# TCP Reno by default
$ns attach-agent $client $tcp_client
# Create a TCP sink at the server
set tcp_sink [new Agent/TCPSink]
$ns attach-agent $server $tcp_sink
# Connect the TCP client and sink
$ns connect $tcp_client $tcp_sink
# Create an FTP application to simulate HTTP traffic
set ftp [new Application/FTP]
$ftp attach-agent $tcp_client
# Start the FTP traffic at time 1.0 seconds
$ns at 1.0 “$ftp start”
# Simulate encryption overhead for HTTPS (add delay)
proc simulate_encryption_delay {pkt} {
global ns
set delay [expr rand() * 10]
$ns at [$ns now + $delay] “forward_packet $pkt”
}
proc forward_packet {pkt} {
puts “Packet forwarded after encryption”
}
# Start encryption delay simulation at time 1.0 seconds
$ns at 1.0 “simulate_encryption_delay packet1”
# End the simulation after 10 seconds
$ns at 10.0 “finish”
# Run the simulation
$ns run
Key Points:
- HTTP/HTTPS Traffic: Replicate web traffic using TCP agents and FTP applications to estimate HTTP and HTTPS communication.
- Encryption Overhead: Insert delays to mimic encryption and decryption overhead for HTTPS.
- Performance Metrics: Investigate throughput, latency, and packet loss to calculate how HTTP and HTTPS perform under distinct network conditions.
- NAM Visualization: We can use NAM to envision how packets pass through the network.
We thoroughly demonstrated the structured stepwise method to simulate HTTP traffic and approximate HTTPS traffic using NS2 simulator. We will also be presented additional insights on this topic, if necessary.
By providing comprehensive information on all relevant HTTP and HTTPS projects, we deliver effective guidance and a clear explanation, assisting you in achieving optimal simulation results.
