Abstract Applications running in data center networks exhibits barrier-synchronized many-to-one communication pattern. Under this pattern, multiple workers synchronously transmit data to single aggregator. Synchronized transmission from multiple workers overload small-sized buffer of switch connected to aggregator. This causes severe packet drops and leads to overall application goodput degradation. This is named as TCP Incast problem in data center network. In this paper, an application layer technique called Delayed Server Response at Application Layer (DSRAL) is proposed to mitigate TCP Incast problem. It is delay-based sequential data transmission technique. In DSRAL, aggregator first determines amount of time required by each worker to finish its data transmission. This can be done by knowing Server Request Unit (SRU) size, average Round Trip Time (RTT) and packet scheduling time. Then along with request packet, aggregator communicates distinct SRU transmission time with each worker and enforces them to transmit SRUs sequentially. Through simulation it is proved that DSRAL avoids TCP Incast problem and provides improved performance than existing application layer serialized method. It supports large number of workers and simultaneously achieves high application goodput without causing any packet loss.
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