Telecommunication Networks

Congestion Management Schemes

Srisankar Kunniyur

Due to tremendous increase in the number of users and applications using the Internet, congestion has become a major problem in today's Internet which has resulted in excessive packet drops and delays in the network. As a result, there has been a surge of interest in designing low-loss and low-delay networks by encouraging users to adapt to changing networks conditions using minimal information from the network. Explicit Congestion Notification (ECN) has been recently proposed [1] to provide early indication to sources about imminent congestion in the network. Current versions of TCP rely on loss as indicators of congestion. Clearly, this is undesirable if one wants to operate the network at low-levels of loss. On the other hand, losses are good indicators of congestion and one needs other signals from the network to make congestion-control decisions with very little or no loss. ECN marking is a mechanism to provide such information about the network to the users.