Dropping Policy for Improving the Throughput of TCP over Optical Burst-Switched Networks.
ABSTRACT Burst loss due to contention in Optical Burst-Switched (OBS) networks significantly degrades the throughput of TCP sources
in the local access networks because TCP congestion control mechanism makes a TCP source enter a slow start phase regardless
of the congestion degree of OBS networks. In this paper, to improve TCP throughput over OBS networks, we first introduce a
dropping policy (DP) with retransmission of the bursts dropped due to contention, by the ingress node. Then, we extend the
DP with retransmission to drop a burst that has experienced fewer retransmissions in the event of contention in order to reduce
the number of events that a TCP source enters the slow start phase due to contention. Additionally, we propose to limit the
number of retransmissions of each burst to prevent severe congestion. For the performance evaluation of the proposed schemes,
we provide an analytic model of TCP throughput over OBS networks. It is shown via numerical and simulation results that the
proposed schemes can achieve better TCP throughput performance than an existing DP without retransmission.
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ABSTRACT: Since its advent in 1981, TCP has been subject to a tremendous amount of research effort and enhancements for achieving better performance over various network environments and application scenarios. Due to the transmission characteristics of optical burst switched networks, such as random burst dropping, retro-blocking (i.e., bursts proceeding or delayed from their actual reservation time slot), burstification delay, and burst signaling delay, TCP could be significantly affected if no corresponding countermeasure and enhancement are developed. In this review article we provide a comprehensive survey on reported studies for TCP enhancements over OBS networks in order to mitigate the numerous side effects due to the buffer- less characteristic of burst transmission. Furthermore, we closely analyze TCP behavior over OBS networks with various burst transmission characteristics while highlighting the open challenges that have not yet been extensively tackled or solved.IEEE Communications Surveys & Tutorials 08/2008; DOI:10.1109/COMST.2008.4564480 · 6.49 Impact Factor