To simulate Link Aggregation Protocol (LACP) projects using NS2, we can simulate the behavior of link aggregation by integrating several physical links into a unique logical link to maximize bandwidth and offer redundancy. Even though NS2 does not directly support LACP that the behavior can be replicated by setting up numerous links among the nodes and considering them as a single logical connection.
Link Aggregation Protocol, part of IEEE 802.1AX, dynamically negotiates and handles the link aggregation, balancing traffic over various physical links. We will mimic this by setting up numerous links among two nodes and distributing traffic over them to simulate load balancing and redundancy.
Here’s is a common method on how to simulate LACP-like behavior in NS2:
Steps to Simulate Link Aggregation (LACP) in NS2
- Set Up NS2 Environment
Make sure NS2 is installed and executing on the machine. We can check this by entering:
ns
This should open the NS2 shell if the installation is effective.
- Understanding Link Aggregation
In Link Aggregation, various physical links are integrated to form a unique logical link. Traffic can be distributed through these links that offering higher bandwidth and fault tolerance. If one link fails then the protocol can reroute traffic over the remaining links without disruption.
- Write a TCL Script to Simulate Link Aggregation (LACP)
Following is an instance script, which configures two nodes are associated by several physical links to replicate link aggregation. The traffic is split among the links.
# Create a simulator object
set ns [new Simulator]
# Open trace and NAM output files
set tracefile [open out.tr w]
set namfile [open out.nam w]
$ns trace-all $tracefile
$ns namtrace-all $namfile
# Define the two nodes involved in link aggregation
set n0 [$ns node]
set n1 [$ns node]
# Create multiple physical links between the nodes (simulating link aggregation)
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
# Enable static routing to simulate the aggregated behavior
$ns rtproto Static
# Create two traffic flows to distribute across the aggregated links
# First UDP agent and flow from n0 to n1
set udp0 [new Agent/UDP]
$ns attach-agent $n0 $udp0
set null0 [new Agent/Null]
$ns attach-agent $n1 $null0
$ns connect $udp0 $null0
# Second UDP agent and flow from n0 to n1
set udp1 [new Agent/UDP]
$ns attach-agent $n0 $udp1
set null1 [new Agent/Null]
$ns attach-agent $n1 $null1
$ns connect $udp1 $null1
# Create CBR traffic generators to simulate traffic distribution across the aggregated links
# First traffic generator
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 512
$cbr0 set interval_ 0.005
$cbr0 attach-agent $udp0
# Second traffic generator
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packetSize_ 512
$cbr1 set interval_ 0.01
$cbr1 attach-agent $udp1
# Schedule the traffic to start and stop
$ns at 1.0 “$cbr0 start”
$ns at 1.5 “$cbr1 start”
$ns at 4.5 “$cbr0 stop”
$ns at 4.5 “$cbr1 stop”
$ns at 5.0 “finish”
# Define the finish procedure
proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exec nam out.nam &
exit 0
}
# Run the simulation
$ns run
- Explanation of the Script
- Multiple Links: Three physical links are made among nodes n0 and n1, which replicating the behavior of link aggregation.
- Traffic Distribution: Two separate traffic flows are made, each using one of the aggregated links. This replicates the load-balancing feature of LACP.
- Static Routing: Traffic is distributed across several links in a way that mimics link aggregation behavior. In a real LACP configuration, the protocol would automatically balance the traffic among the links.
- Running the Simulation
We can save the script as lacp_simulation.tcl and then execute it in the terminal:
ns lacp_simulation.tcl
It will make a trace file (out.tr) and a NAM file (out.nam) for network visualization.
- Visualizing the Simulation
To envision the simulation using NAM, execute:
nam out.nam
In NAM, we will observe various links among the two nodes including traffic flowing across these links to replicate link aggregation.
- Simulating Link Failures and Recovery
We can replicate link failures to monitor how traffic is rerouted over the remaining links in case of a failure. For instance, we can replicate a failure of one of the links:
# Simulate link failure at 2.0 seconds
$ns rtmodel-at 2.0 down $n0 $n1 1 ;# Disable one of the links
# Restore the link at 3.5 seconds
$ns rtmodel-at 3.5 up $n0 $n1 1 ;# Re-enable the link
It will replicate the failover behavior in which traffic is rerouted over the remaining links once a link goes down.
- Analyzing the Trace File
The trace file (out.tr) encompasses detailed data regarding packet transmissions, link failures, and traffic flow. We can be used grep or awk to extract key performance parameters like:
- Packet Delivery Ratio (PDR): The percentage of effectively delivered packets.
- Link Utilization: Calculate how traffic is distributed across numerous links and how failover is managed.
For instance, to compute the number of packets received:
grep “^r” out.tr | wc -l
- Performance Evaluation
We can estimate the performance of the replicated LACP by:
- Increasing the number of links: Insert more physical links among the nodes to replicate a larger link aggregation group.
- Varying traffic load: Modify the traffic generator metrics to mimic diverse levels of network traffic.
- Simulating different failure scenarios: Experiment how the network executes when several links fail and retrieve.
Through the entire approach, you can acquire the simulation and execution process for Link Aggregation Protocol projects offered in it using NS2 tool. We are furnished to offer the demonstration steps of these projects through another manual for you.
We specialize in the Link Aggregation Protocol, which is a component of IEEE 802.1AX. This protocol dynamically negotiates and manages link aggregation, effectively balancing traffic for your projects. Simply provide us with the details of your Link Aggregation Protocol project, and we will offer you expert simulation assistance along with insights on current trends.
