A network consists of various devices or resources. Each resource is assigned to perform a particular task. Sometimes the available resources are more but the task or load to be performed is less whereas sometimes it is completely opposite. In such scenarios when the load is more as compared to the available resources in the network it is known as congestion. Many times to control such congestion either load is decreased or resources are increased. But this does not work properly for the networks. Various techniques are used for congestion control.

What is Load Shedding?

Load shedding is one of the techniques used for congestion control. A network router consists of a buffer. This buffer is used to store the packets and then route them to their destination. Load shedding is defined as an approach of discarding the packets when the buffer is full according to the strategy implemented in the data link layer. The selection of packets to discard is an important task. Many times packets with less importance and old packets are discarded.

Selection of Packets to be Discarded

In the process of load shedding the packets need to be discarded in order to avoid congestion. Therefore which packet needs to be discarded is a question. Below are the approaches used to discard the packets.

1. Random Selection of packets

When the router is filled with more packets, the packets are selected randomly for discarding. Discarding the packets it can include old, new, important, priority-based, or less important packets. Random selection of packets can lead to various disadvantages and problems.

2. Selection of packets based on applications

According to the application, the new packets will be discarded or old packets can be discarded by the router. When the application is regarding file transfer new packets are discarded and when the application is regarding multimedia the old packets are discarded.

3. Selection of packets based on priority

The source of packets can mark the priority stating how much important the packet is. Depending upon the priority provided by the sender the packet can either be selected or discarded. The priority can be given according to price, algorithm, and methods used, the functions that it will perform, and its effect on another task upon selecting and discarding the packets.

4. Random early detection

Randomly early detection is an approach in which packets are discarded before the buffer space becomes full. Therefore the situation of congestion is controlled earlier. In this approach, the router initially maintains a specific queue length for the outgoing lines. When this average set line is exceeded it warns for congestion and discards the packets.

Advantages of Load Shedding

• Using the load shedding technique can help to recover from congestion.
• Load shedding technique reduces the flow of network traffic.
• It discards the packet from the network before congestion occurs
• Load shedding maintains a synchronized flow of packets in the network.

Disadvantages of Load Shedding

• If the size of the buffer is very less it discards more packets
• It is an overhead task for the router to continuously check if it has becomes full.
• Load shedding can sometimes discard important packets also considered as old packets.
• Load shedding cannot completely guarantee the avoidance of congestion.

FAQs on Load Shedding

1. What are other techniques used for controlling congestion in networks?

Various techniques used for controlling congestion in networks are traffic throttling, admission control, network provisioning, traffic-aware routing, etc.

2. How the packets are filtered based on priority in the load-shedding technique?

The source of the packet sends it with priority. Therefore when congestion occurs these priorities are checked. Packets with less priority are discarded.

3. What is the need for load shedding?

Load shedding is required in order to avoid the congestion. During load shedding the packets are discarded when the buffer is full.

4. What are the risks encountered during the implementation of congestion?

The risks encountered during congestion are the important packets might also get discarded, and it cannot guarantee the solution for congestion completely.