Bandwidth Management

Bandwidth management refers to the methods used to monitor and control data transmission over a network to prevent congestion and ensure smooth communication. Bandwidth, represented by bit rate and measured in bits per second (bit/s) or bytes per second (B/s), is the capacity of a network link to handle data.

Effective bandwidth management involves several mechanisms and techniques to optimize performance and avoid overloading the network:

1. Traffic Shaping: Also known as rate limiting, it regulates the data flow into a network. Techniques like the Token Bucket and Leaky Bucket algorithms help control this flow. TCP rate control is another method where the TCP window size is adjusted, and the rate of ACKs (Acknowledgements) sent back to the sender is controlled.
2. Scheduling Algorithms: These algorithms manage how data packets are handled by network devices, ensuring fair distribution. Examples include Weighted Fair Queuing (WFQ), Class-Based Weighted Fair Queuing, Weighted Round Robin (WRR), Deficit Weighted Round Robin (DWRR), and Hierarchical Fair Service Curve (HFSC).
3. Congestion Avoidance: This involves techniques to prevent network congestion before it happens. Methods like Random Early Detection (RED), Weighted RED (WRED), and Policing (which marks or drops excess packets) help in managing traffic. Explicit Congestion Notification (ECN) and Buffer Tuning, which adjusts router memory allocation, are also used.
4. Bandwidth Reservation Protocols: Protocols like Resource Reservation Protocol (RSVP) and Constraint-based Routing Label Distribution Protocol (CR-LDP) enable applications to request specific network resources. Algorithms like the Top-nodes algorithm assist in efficient bandwidth allocation.
5. Traffic Classification: This process categorizes network traffic based on policies to apply appropriate management techniques to different traffic types.

Issues that can affect link performance include the TCP protocol's management of connection capacity, router queuing that increases latency and jitter, TCP global synchronization wasting bandwidth, and the burstiness of web traffic requiring extra bandwidth. Additionally, lack of support for ECN and QoS management on the Internet, as well as ISP control over queue management, can limit performance. Finally, tools like packet sniffers, which monitor network traffic, and traffic measurement techniques are essential for effective bandwidth management.