How to Implement IEEE 802.1Q VLAN Tagging in ns2

To implement the IEEE 802.1Q VLAN tagging within the tool NS2 (Network Simulator 2) that can be challenging since the simulator NS2 does not have native assist for the VLANs or the 802.1Q standard. But, we can mimic VLAN behaviour by expanding the competences of the NS2 using custom code and TCL scripts. The following procedure on how effectively to approach the execution of VLAN tagging in NS2.

Step-by-Step Implementation:

  1. Understand the Basics of VLAN Tagging:
  • IEEE 802.1Q is a networking standard that assist the Virtual Local Area Networks (VLANs) on an Ethernet network. It needs to include tagging Ethernet frames with a VLAN ID to find the VLAN to which the frame belongs.
  1. Set Up the NS2 Environment:
  • Make sure NS2 is installed on the system.
  • Get to know the writing TCL scripts and possibly extending NS2 with C++ if required.
  1. Simulating VLAN Behavior:
  • Since NS2 doesn’t natively assist VLANs, we can mimic VLAN behaviour by marking packets including the VLAN tags and controlling how packets are routed among the nodes according to these tags.
  1. Define the Network Topology:
  • Make a nodes and links in NS2 as we could for a normal network. We will have to mimic VLAN-aware switches using custom logic.

# Define the simulator

set ns [new Simulator]

# Create a trace file

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Create a NAM file for animation

set namfile [open out.nam w]

$ns namtrace-all $namfile

# Create the nodes

set n0 [$ns node]

set n1 [$ns node]

set n2 [$ns node]

set n3 [$ns node]

set n4 [$ns node]  ;# This node will act as a VLAN-aware switch

# Create links between nodes

$ns duplex-link $n0 $n4 100Mb 10ms DropTail

$ns duplex-link $n1 $n4 100Mb 10ms DropTail

$ns duplex-link $n2 $n4 100Mb 10ms DropTail

$ns duplex-link $n3 $n4 100Mb 10ms DropTail

  1. Simulate VLAN Tagging:
  • Generate a custom procedure in the TCL to mimic VLAN tagging. We can denote the VLAN tags with custom fields or variables in the packets.

# Define a custom procedure to add VLAN tags to packets

proc add_vlan_tag {pkt vlan_id} {

$pkt set_vtag $vlan_id

}

# Define a custom procedure to check and route packets based on VLAN tags

proc route_vlan_packet {src dst pkt} {

set vlan_id [$pkt get_vtag]

if {$vlan_id == 10} {

$ns connect $src $dst ;# Route within VLAN 10

} elseif {$vlan_id == 20} {

$ns connect $src $dst ;# Route within VLAN 20

} else {

drop $pkt ;# Drop the packet if it doesn’t belong to a valid VLAN

}

}

  1. Create Traffic Sources and Add VLAN Tags:
  • Make the traffic sources such as TCP or UDP and append the VLAN tags to the packets.

# Create a TCP agent and attach it to node n0

set tcp0 [new Agent/TCP]

$ns attach-agent $n0 $tcp0

# Create a Null agent as the sink and attach it to node n2

set sink0 [new Agent/Null]

$ns attach-agent $n2 $sink0

# Connect the agents via the VLAN-aware switch

$ns at 0.1 “add_vlan_tag $tcp0 10”

$ns at 0.1 “route_vlan_packet $tcp0 $sink0 $tcp0”

# Create an FTP application and attach it to the TCP agent

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

# Start the FTP transfer at 0.5 seconds

$ns at 0.5 “$ftp0 start”

  1. Implement VLAN Routing Logic:
  • Expand the TCL script to route packets according to the VLAN tags and this could mimic the behaviour of a VLAN-aware switch.

# Example of routing logic within the switch (n4)

proc vlan_switch_logic {pkt} {

set vlan_id [$pkt get_vtag]

switch $vlan_id {

10 {

$ns connect $pkt $n0 $n2 ;# Route VLAN 10 packets

}

20 {

$ns connect $pkt $n1 $n3 ;# Route VLAN 20 packets

}

default {

drop $pkt ;# Drop packets that don’t match any VLAN

}

}

}

# Apply the VLAN switch logic to packets arriving at the switch (n4)

$n4 set ragent_ [vlan_switch_logic]

  1. Run and Analyse the Simulation:
  • State when the simulation should terminate and execute it.

# Define the finish procedure

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam out.nam &

exit 0

}

# Schedule the finish procedure at 5 seconds

$ns at 5.0 “finish”

# Run the simulation

$ns run

  1. Visualize and Analyse the Results:
  • We can use the NAM to visualize the simulation and observe how VLAN tags affect packet routing.
  • Evaluate the trace file to know how packets are being managed and routed according to the VLAN tags.

In this entire page, we demonstrated on how to implement and evaluate the IEEE 802.1Q VLAN Tagging through the use of the suggested method. Further details will be shared based on your needs. We provide customized help for implementing IEEE 802.1Q VLAN Tagging in ns2, designed just for you. Our project guidance is top-notch so share with us all your research details to guide you more.