UDP - TCP- Congestion Control – Presentation aspects.

User Datagram Protocol (UDP)

Transmission Control Protocol(TCP)

Congestion control in computer networks is a set of techniques and strategies used to manage and relieve network congestion, ensuring that the network operates efficiently and effectively even during periods of high traffic. 

Congestion can happen when the demand for network resources, such as bandwidth and processing capacity, exceeds the available supply, leading to degraded performance, increased latency, and packet loss. 

Here are some key aspects of congestion control in network environment

1.Traffic Policing and Shaping

• • Traffic Policing- Network devices, such as routers and switches, can enforce traffic limits by discarding or marking packets that exceed specified rate limits. This prevents excessive traffic from entering the network.

  • Traffic Shaping Rather than discarding excessive traffic, traffic shaping smooths out traffic bursts by buffering and releasing packets at a controlled rate. This helps in avoiding sudden spikes in network congestion.

2.Quality of Service (QoS)

• • QoS mechanisms prioritize certain types of traffic over others based on predefined rules. This ensures that critical or real-time traffic (e.g., VoIP, video conferencing) receives better treatment than less time-sensitive traffic.

3.Window-Based Congestion Control (TCP)

• • In the Transmission Control Protocol (TCP), which is widely used for reliable data transmission, window-based congestion control mechanisms adjust the rate at which a sender transmits data based on feedback from the network.

  • TCP uses techniques like the Slow Start, Congestion Avoidance, and Fast Recovery algorithms to dynamically adapt the sender's transmission rate to the network's congestion level.

4.Explicit Congestion Notification (ECN):

• • ECN allows routers to mark packets as they pass through congested areas of the network. The sender receives this feedback and can adjust its transmission rate accordingly, avoiding further congestion.

5.Random Early Detection (RED) and Active Queue Management (AQM):

• • RED is a queue management algorithm that helps routers manage congestion by dropping or marking packets when the queue length exceeds a certain threshold. This encourages sources to reduce their sending rates.

  • AQM extends RED by actively managing the queue length to maintain an optimal balance between low latency and high throughput.

6.Load Balancing:

• • Distributing incoming network traffic across multiple paths or resources helps prevent any single point of congestion. Load balancers ensure that no individual component becomes overwhelmed.

7.Multipath Routing

• • Using multiple paths for data transmission can help avoid congestion on a single path. Multipath routing algorithms dynamically select paths based on current network conditions.

8.Congestion-Aware Routing:

• • Some routing algorithms take congestion into account when selecting paths for data transmission. They avoid routes with high congestion and prefer paths with lower traffic loads.

9.Feedback Mechanisms:

• • Congestion control often relies on feedback from routers, switches, and endpoints to adjust transmission rates and routing decisions.

10.Network Monitoring and Measurement:

• Monitoring tools continuously assess network performance and congestion levels. This data is crucial for making informed decisions about congestion control strategies.

Congestion control is a complicated and ongoing challenge in network engineering. 

Effective congestion control mechanisms ensure that networks can handle varying levels of traffic while providing a consistent, reliable experience for users and applications.