Early Window Tailoring: A New Approach to Increase the Number of TCP Connections Served

Marcos Talau,Mauro Fonseca,Emilio C G Wille

doi:10.1155/2019/2187543

Marcos Talau, Mauro Fonseca + Show 1 more

Open Access

https://doi.org/10.1155/2019/2187543

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Abstract

In the absence of losses, TCP constantly increases the amount of data sent per instant of time. This behavior leads to problems that affect its performance, especially when multiple devices share the same gateway. Several studies have been done to mitigate such problems, but many of them require TCP side changes or a meticulous configuration. Some studies have shown promise, such as the use of gateway techniques to change the receiver’s advertised window of ACK segments based on the amount of memory in the gateway; in this work, we use the term “network-return” to refer to these techniques. In this paper, we present a new network-return technique called early window tailoring (EWT). For its use, it does not require any modification in the TCP implementations at the sides and does not require that all routers in the path use the same congestion control mechanism, and the use in the gateway is sufficient. With the use of the simulator ns-3 and following the recommendations of RFC 7928, the new approach was tested in multiple scenarios. The EWT was compared to drop-tail, RED, ARED, and the two network-return techniques—explicit window adaptation (EWA) and active window management (AWM). In the results, it was observed that EWT was shown to be efficient in congestion control. Its use avoided losses of segments, bringing expressive gains in the transfer latency and goodput and maintaining fairness between the flows. However, unlike other approaches, the most prominent feature of EWT is its ability to maintain a very high number of active flows at a given level of segment loss rate. The EWT allowed the existence of a number of flows, which is on average 49.3% better than its best competitor and 75.8% better when no AQM scheme was used.

Highlights

Unlike other approaches, the most prominent feature of early window tailoring (EWT) is its ability to maintain a very high number of active flows at a given level of segment loss rate. e EWT allowed the existence of a number of flows, which is on average 49.3% better than its best competitor and 75.8% better when no active queue management (AQM) scheme was used
(1) TCP Efficiency. e results are presented in Figure 11. e efficiency of the drop-tail, random early detection (RED), and adaptive RED (ARED) methods was similar, with a small difference in medium and heavy congestion. e explicit window adaptation (EWA) and active window management (AWM) had a small loss of efficiency with heavy congestion. e EWT maintained the TCP efficient at the three levels of congestion
We presented a new network-return technique called early window tailoring (EWT). e approach was applied in multiple scenarios

Summary

Motivation

Disregarding the problem of misleading reduction, where losses in the physical layer cause TCP to reduce its transmission rate improperly, there are problems that occur in an internetwork environment. Is method is designed to work with UDP and TCP traffic [14] Just like others, it changes the value contained in the receiver’s advertised window of ACK segments. Is control is done by updating the value contained in the receiver’s advertised window (Wr) of TCP ACK segments based on the number of bytes available in the gateway’s memory. New flows tend to have their congestion window low, so the return of the EWT would not have an immediate effect; to mitigate this and to save resources of the gateway when the memory usage is low, the parameter St is used to define the start-up point of the method.

Results

Conclusion and Future Work