Can we multiplex ACKs without harming the performance of TCP?

This paper explores the application of traffic optimization techniques, based on header compression and multiplexing, to the flow of ACKs sent by a TCP client when downloading a file. Significant compression rates can be obtained, but a multiplexing delay has to be added as a counterpart. The influence of this delay in TCP dynamics is explored by means of simulations including FTP flows sharing a bottleneck. The results show that the impairments can be maintained in reasonable limits, by selecting proper values of the multiplexing period. Thus, the multiplexing of these ACK flows can be further studied and considered as a possibility for traffic optimization.

I. Introduction

The increase of emerging real-time services using small packets is modifying the traffic mix present on the Internet [1]. These services make an inefficient use of the network, especially when the header and the payload length are in the same order of magnitude. This problem is stressed for IPv6, which header is twice as big as that of IPv4.