RFC 2963 (rfc2963) - Page 1 of 19
A Rate Adaptive Shaper for Differentiated Services
Alternative Format: Original Text Document
Network Working Group O. Bonaventure
Request for Comments: 2963 FUNDP
Category: Informational S. De Cnodder
Alcatel
October 2000
A Rate Adaptive Shaper for Differentiated Services
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This memo describes several Rate Adaptive Shapers (RAS) that can be
used in combination with the single rate Three Color Markers (srTCM)
and the two rate Three Color Marker (trTCM) described in RFC 2697 and
RFC 2698, respectively. These RAS improve the performance of TCP when
a TCM is used at the ingress of a diffserv network by reducing the
burstiness of the traffic. With TCP traffic, this reduction of the
burstiness is accompanied by a reduction of the number of marked
packets and by an improved TCP goodput. The proposed RAS can be used
at the ingress of Diffserv networks providing the Assured Forwarding
Per Hop Behavior (AF PHB). They are especially useful when a TCM is
used to mark traffic composed of a small number of TCP connections.
1. Introduction
In DiffServ networks [RFC 2475], the incoming data traffic, with the
AF PHB in particular, could be subject to marking where the purpose
of this marking is to provide a low drop probability to a minimum
part of the traffic whereas the excess will have a larger drop
probability. Such markers are mainly token bucket based such as the
single rate Three Color Marker (srTCM) and two rate Three Color
Marker (trTCM) described in [RFC 2697] and [RFC 2698], respectively.
Similar markers were proposed for ATM networks and simulations have
shown that their performance with TCP traffic was not always
satisfactory and several researchers have shown that these
performance problems could be solved in two ways:
Bonaventure & De Cnodder Informational