RFC 2140 (rfc2140) - Page 1 of 11

TCP Control Block Interdependence

Network Working Group                                           J. Touch
Request for Comments: 2140                                           ISI
Category: Informational                                       April 1997


                   TCP Control Block Interdependence

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.


Abstract

   This memo makes the case for interdependent TCP control blocks, where
   part of the TCP state is shared among similar concurrent connections,
   or across similar connection instances. TCP state includes a
   combination of parameters, such as connection state, current round-
   trip time estimates, congestion control information, and process
   information.  This state is currently maintained on a per-connection
   basis in the TCP control block, but should be shared across
   connections to the same host. The goal is to improve transient
   transport performance, while maintaining backward-compatibility with
   existing implementations.

   This document is a product of the LSAM project at ISI.


Introduction

   TCP is a connection-oriented reliable transport protocol layered over
   IP [9]. Each TCP connection maintains state, usually in a data
   structure called the TCP Control Block (TCB). The TCB contains
   information about the connection state, its associated local process,
   and feedback parameters about the connection's transmission
   properties. As originally specified and usually implemented, the TCB
   is maintained on a per-connection basis. This document discusses the
   implications of that decision, and argues for an alternate
   implementation that shares some of this state across similar
   connection instances and among similar simultaneous connections. The
   resulting implementation can have better transient performance,
   especially for numerous short-lived and simultaneous connections, as
   often used in the World-Wide Web [1]. These changes affect only the
   TCB initialization, and so have no effect on the long-term behavior
   of TCP after a connection has been established.




Touch                        Informational