In the context of networks, congestion is defines as a network state where a link or node carries so much data, hence reducing the network service quality. This leads to queuing delay, data packet or frame loss as well as blocking of new connections (Lu, et al., 2017). The internet is designed as a queue of packets constituting the transmitting nodes with constantly adding packets and the receiving nodes are constantly removing packets from the queue. In some cases too many packets can be present in the queue so that the transmitting nodes are adding packets at higher rate than receiving nodes are removing them. In simple terms, congestion is described as condition where there is more number of packets in the network than it can handle.
Common causes of congestion
There are several conditions that leads to congestion in the network. For instance, a network or internet receives so many stream of packets all over a sudden from several input lines and these stream is required to be out of the network through the same output line, thus building a long queue in the network (Lu, et al., 2017). If the network system does not have enough memory to hold the packets, these packets are likely to be dropped. The other cause is associated with infinite amount of memory in the router which cannot be expanded. As the packets reaches the head of the queue to be removed through the outline, they have already been timed-out hence creating duplicates.
Slow processor is the also another cause of congestion. When the router CPU performs the required task such as reporting any exceptions, updating tables or queuing buffer at a slower rate, queue is likely to build up even when the line has excess capacity. Similarly, Low-Bandwidth line also leads to congestion since it can receives so much packets and dispatches them at a slower rate.
The role of a bridge or a switch in network congestion
A bridge or a switch can create congestion in a network by linking more stations to a single network.
Techniques deploy to resolve the issue of congestion
There are two broad techniques that can be deployed to control congestion in a network: open loop and close loop. Open loop is described as a protocol deployed to control congestion by ensuring that the network or a system does not enter into a congestion state (Kelly, 2003). On the other hand, closed loop is a mechanism that allows the network or a system to enter into a congested state, detect the congestion and get rid of it. The other techniques for controlling congestion in a network are network-based and host-based mechanism. Network-based involves the implementation and enforcement of the bandwidth allocation in a network. Host-based technique can be deployed to control the sending rate.
The most effective technique
In my opinion, the most effective technique for controlling congestion in a network is open loop technique. This technique is effective because it involves traffic shaping, admission control, choke packets and load shedding (Zhang, et al., 2014). This technique uses VC subnets such as ATM networks as well as avoiding bursty traffic by producing a more uniform output at the hosts.
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