Evaluating-Network-switch-Scheduling-algorithm

A Python/Jupyter Notebook project that simulates and compares packet scheduling algorithms used in input-queued crossbar switches.

This project evaluates how scheduling policies impact:

• Total service time
• Average packet delay
• Throughput
• Queue backlog
• Head-of-Line (HoL) blocking

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Algorithms Implemented

1. FIFO (First-In First-Out)

Each input port has one queue.

Characteristics

• Simple and easy to implement
• Only the head packet can be transmitted
• Suffers from Head-of-Line blocking

Observed Performance

• Highest delay
• Lowest throughput

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2. Optimal VOQ (Virtual Output Queuing)

Each input port maintains separate queues for each output port.

Characteristics

• Eliminates HoL blocking
• Finds maximum matching every slot
• Gives best possible scheduling result

Observed Performance

• Highest throughput
• Best service efficiency

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3. iSLIP

A practical iterative matching scheduler used in real switches.

Characteristics

• Request → Grant → Accept phases
• Round-robin fairness using pointers
• Lower complexity than exhaustive optimal matching

Observed Performance

• Much better than FIFO
• Near-optimal in practice

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Project Structure

Evaluating-Network-switch-Scheduling-algorithm/
│── switch_simulation.ipynb
│── Results/
│   ├── switch_simulation_results.png
│   ├── FIFO_Packet_Timeline.png
│   └── iSLIP_Packet_Timeline.png
│── README.md

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Requirements

Install dependency:

pip install matplotlib

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How to Run

Run in Jupyter Notebook

jupyter notebook

Open:

switch_simulation.ipynb

Run all cells in order.

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Notebook Sections

1. Imports & Setup
2. Packet Class
3. Switch Classes
   • FIFOSwitch
   • OptimalVOQSwitch
   • iSLIPSwitch
4. Packet Loader
5. Simulation Runners
   • FIFO Runner
   • OptimalVOQ Runner
   • iSLIP Runner
6. Visualization Functions
7. Metrics Functions
8. Main Execution

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Results Generated

Saved inside:

Results/

Output Files

• switch_simulation_results.png → Comparison graphs
• FIFO_Packet_Timeline.png → FIFO packet schedule
• iSLIP_Packet_Timeline.png → iSLIP packet schedule

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Performance Metrics (Actual Output)

Algorithm	Average Delay	Throughput (packets/slot)
FIFO	2.22	1.636
Optimal VOQ	—	2.571
iSLIP	1.06	2.250

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Analysis

FIFO

• Highest delay due to HoL blocking
• Lowest throughput
• Inefficient under contention

Optimal VOQ

• Best throughput among all algorithms
• Fully utilizes switch fabric
• Computationally expensive for large systems

iSLIP

• Delay reduced significantly vs FIFO
• Throughput close to optimal
• Practical and scalable solution

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Key Learning Outcomes

• FIFO queues can waste switch capacity
• VOQ removes Head-of-Line blocking
• Maximum matching improves utilization
• iSLIP balances performance and complexity

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Technologies Used

• Python
• Jupyter Notebook
• Matplotlib
• deque (queue simulation)

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Author

Deepanshu Sharma
IIT Guwahati

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License

Educational / Academic Use