TCP ETS: Extensible Timestamp Options

Document Type Expired Internet-Draft (individual)
Authors Kevin Yang  , Neal Cardwell  , Yuchung Cheng  , Eric Dumazet 
Last updated 2021-05-06 (latest revision 2020-11-02)
Stream (None)
Intended RFC status (None)
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document presents ETS: an Extensible TimeStamps option for TCP. It allows hosts to use microseconds as the unit for timestamps to improve the precision of timestamps, and advertise the maximum ACK delay for its own delayed ACK mechanism. Furthermore, it extends the information provided in the [RFC7323] TCP Timestamps Option by including the receiver delay in the TSecr echoing, so that the receiver of the ACK is able to more accurately estimate the portion of the RTT that resulted from time traveling through the network. The ETS option format is extensible, so that future extensions can add further information without the overhead of extra TCP option kind and length fields.


Kevin Yang (
Neal Cardwell (
Yuchung Cheng (
Eric Dumazet (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)