engleski

TCP ECN in ATM Network

TCP's reactive congestion control scheme of droping packets has the advantage of not making any assumptions about the operation of the underlying network layer but it is inadequate for high speed networking. The explicit congestion notification (ECN) is a mechanism which provides IP networks with means to inform end-system TCPs of incipient congestion. For congestion notification in ATM networks, ATM switches can use the Explicit Forward Congestion Indication (EFCI) bit in an ATM cell header. Unfortunately, the setting of the EFCI bit is not based on the average but on the instantaneous queue size. Because of this, the EFCI bit is generally considered not applicable for ECN. Nevertheless, this article explores possible ways of using EFCI in ECN scheme because such a configuration would greatly benefit TCP traffic passing through ATM network. The simulation results obtained by using the xGlobe network simulator are analyzed. The ECN/EFCI congestion control has been implemented in the Linux kernel which provides a platform for further testing. Finally, several implementation issues are discussed.

ECN; ATM; EFCI; Congestion Control

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