Network Congestion is networking condition which could happen when there are too many sources sending too much data too fast for network to handle. This phenomenon could be observed when there are packet losses (due to buffer overflow at Routers and increasing end-to-end delays (due to queuing in router buffers). The result is the unfairness and poor utilisation of network resources due to resources used by dropped packets before they were lost, retransmissions, and poor resource allocation at high load.
Network Congestion
- TTP3121 Chapter 1: Introduction
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Switch
Switch provides means to resolve Network Congestion#, e.g. Quality of Service (QoS)#
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Scavenger QoS
Scavenger QoS imposes a traffic limit on ports, and if the packets exceeding the limits, it will be marked to lower priority, and might be dropped eventually. If we know an application’s normal behaviour on a device and on the network, a safeguard could be built using Scavenger QoS to recognise and stop the application upon abnormal behaviours. It works in the opposite way of Quality of Service (QoS)#. It reduces Network Congestion and possible DDoS or worm attacks especially if the attacks create a traffic spike (exceeding bandwidth thresholds) for sustained periods.
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Quality of Service (QoS)
QoS is the ability of a network to provide improved service to selected network traffic over various underlying technologies. The increasing need for real-time traffics such as video streaming and VoIP has made QoS as an important requirement for a #reliable network. It decreases the Network Congestion# and the effect on the quality of the critical packets especially low delay and low jitter. QoS can potentially filter out malicious low prioritised packets (from unknown type or origin) as a policing mechanism, but it is still vulnerable to DDoS and concealed traffic.
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Frame Relay
To deal with network congestion#, Frame Relay switching equipment can mark a Frame Relay packet with forward explicit congestion notification (FECN) or backward explicit congestion notification (BECN). The former will be sent to the destination device whereas the latter will be sent to the source router. The respective DTE equipment will notify higher layer about the congestion based on such mark, and decide whether act accordingly or ignore such messages. Other than FECN and BECN, the packet could be marked as discard eligible (DE), which enable the switching equipment to drop it whenever there is a congestion.
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Bridge
It will learn all the addresses of the computers that connected to it and only transfer the network traffic to the destination device or the network that contains it. This can reduce the occurrence of the collisions and improve the Network Congestion#.