Measurement of RTT and calculation of RTO in TCP_Broad sea and sky sky1992’s blog
Kernel version: 3.2.12 This article mainly analyzes: RTT measurement, RTO calculation Author: zhangskd @ csdn Link: http://blog.csdn.net/zhangskd/ article/details/7196707 Overview RTO (Retransmission TimeOut) is the retransmission timeout. A very important part of TCP timeouts and retransmissions is the measurement of the round trip time (RTT) for a given connection. Due to changes in network traffic, this time will change accordingly, and TCP needs to track these changes and dynamically adjust the timeout RTO. RTO is described in this way in RFC2988: “The Transmission Control Protocol (TCP) uses a retransmission timer to ensure data delivery in the absence of any feedback from the remote data receiver. The duration of this timer is referred to as RTO (retransmission timeout).” RTT (Round Trip Time) consists of three parts: link Propagation delay, processing time in end systems, queuing and processing time in router caches (queuing delay). Among them, the values of the first two parts are relatively fixed for a TCP connection, and the queuing and processing time in the router cache will change with the change of the entire network congestion. Therefore, the change of RTT reflects the degree of network congestion to a certain extent. average Deviation Mean deviation, abbreviated as mdev. It…
