TCP Control Block Interdependence

The information below is for an old version of the document
Document Type Expired Internet-Draft (tcpm WG)
Authors Joseph Touch  , Michael Welzl  , Safiqul Islam 
Last updated 2020-10-31 (latest revision 2020-04-29)
Replaces draft-touch-tcpm-2140bis
Stream Internet Engineering Task Force (IETF)
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state In WG Last Call (wg milestone: Jul 2020 - Submit document on T... )
Document shepherd Michael Scharf
IESG IESG state Expired
Consensus Boilerplate Unknown
Telechat date
Responsible AD (None)
Send notices to Michael Scharf <>

This Internet-Draft is no longer active.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


This memo provides guidance to TCP implementers that are intended to help improve convergence to steady-state operation without affecting interoperability. It updates and replaces RFC 2140's description of interdependent TCP control blocks and the ways that part of TCP state can be shared among similar concurrent or consecutive connections. TCP state includes a combination of parameters, such as connection state, current round-trip time estimates, congestion control information, and process information. Most of this state is maintained on a per-connection basis in the TCP Control Block (TCB), but implementations can (and do) share certain TCB information across connections to the same host. Such sharing is intended to improve overall transient transport performance, while maintaining backward-compatibility with existing implementations. The sharing described herein is limited to only the TCB initialization and so has no effect on the long-term behavior of TCP after a connection has been established.


Joseph Touch (
Michael Welzl (
Safiqul Islam (

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