Revisiting TCP Outcast Problem Using DCTCP in Data Center Networks

Data Center Networks (DCNs) today are used to compute and store the data of multiple users because of low cost, flexibility and availability. In this multi-tenant cloud environment, resources are shared among different users. Suppose two users fetch data at same time from the same DCNs, one fetches small amount of data (like web search) while another user fetches larger amount of data (like software update). If these large set of flows and small set of flows arrive at two different input ports of a switch and compete for same output port, then large flow packets get the buffer while small flow packets are dropped consecutively. This issue occurs due to drop tail implementation of queue in switches and as one set of flows is outcast by other, the problem is known as TCP Outcast. While a few studies have already explored the TCP Outcast problem, this paper aims to revisit this problem by using DCTCP in DCNs. The experiments carried out using Mininet show that DCTCP solves the problem of TCP Outcast by ensuring fairness for all types of flows.