TCP/IP explanation-Timestamp Option in TCP Header Options

I. Introduction

The TCP timestamp option adds 12 bytes to the TCP Header, enabling RTT calculation in a more precise way than the specific proportion of timeout.

 

Ii. Functions

1) The TCP timestamp is in the TCP option, kind =8; Lenth =10Data consists of two values: Timestamp and timestamp echo, each of which has a length of 4 bytes.2The theory of TCP timestamp has three functions: Serial Number rewinding, time judgment basis for disordered order, avoiding confirming ambiguity and calculating RTT.3) TCP timestamp: both parties maintain their own timestamps. The timestamp value increases monotonically with time (defined as 1 ms-1 S/time, the common values are 1 ms and 10 ms ). The local end sends the timesstamp value. After receiving the message, the peer returns the timestamp echo of the ACK to the local end and sends its own timestamp. TCP records the sending Timestamp and response time to obtain the RTT.

 

Iii. Common Operations

1) enable

Net. ipv4.tcp _ timestamps =1

2) Disable

Net. ipv4.tcp _ timestamps =0

TCP/IP explanation-Timestamp Option in TCP Header Options