On making TCP more robust to packet reordering

Abstract

Previous research indicates that packet reordering is not a rare event on some Internet paths. Reordering can cause performance problems for TCP's fast retransmission algorithm, which uses the arrival of duplicate acknowledgments to detect segment loss. Duplicate acknowledgments can be caused by the loss of a segment or by the reordering of segments by the network. In this paper we illustrate the impact of reordering on TCP performance. In addition, we show the performance of a conservative approach to "undo" the congestion control state changes made in conjunction with spurious retransmissions. Finally, we propose several alternatives to dynamically make the fast retransmission algorithm more tolerant of the reordering observed in the network and assess these algorithms.

A Performance Study of Loss Detection/Recovery in Real-world TCP Implementations

“…Several techniques have been designed to (i) detect and rectify the adverse impact of spurious retransmissions in an ongoing TCP transfer [17], [18], [19], [20], [21], and (ii) detect losses using alternate mechanisms [22], [23], [24], [25], [26], [27]. Unfortunately, due to deployment hurdles, most of these techniques have not been widely deployed in TCP implementations.…”

A Design for an Internet Router with a Digital Optical Data Plane

“…Recirculation systems handle output port collision by sending colliding packets to a set of fiber delay lines (FDLs) of different delay, in which those packets are returned to the input for a new attempt at switching [34][35][36][37]. Recirculation causes packet reordering, which can severely affect some protocols [38]. Some switches handle only fixed-sized packets that arrive aligned (synchronously) [35], whereas others recirculate variable-length packets into FDLs of different length [37] or have input ports with one FDL staging area for each output port [39].…”

Robust TCP (TCP-R) with Explicit Packet Drop Notification (EPDN) for Satellite Networks

“…In [4], the authors use the DSACK information to detect whether the retransmission is spurious and propose various techniques to increase the value of dupthresh value. The main drawback in this proposal is that if the packets had in fact been dropped, having an increased value of dupthresh would not allow the dropped packets to be retransmitted quickly and the dupthresh value would be decreased to three dupacks upon a timeout.…”