Network Working Group J. Heinanen Request for Comments: 2698 Telia Finland Category: Informational R. Guerin University of Pennsylvania September 1999 A Two Rate Three Color Marker 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 (1999). All Rights Reserved.
AbstractThis document defines a Two Rate Three Color Marker (trTCM), which can be used as a component in a Diffserv traffic conditioner [RFC2475, RFC2474]. The trTCM meters an IP packet stream and marks its packets based on two rates, Peak Information Rate (PIR) and Committed Information Rate (CIR), and their associated burst sizes to be either green, yellow, or red. A packet is marked red if it exceeds the PIR. Otherwise it is marked either yellow or green depending on whether it exceeds or doesn't exceed the CIR.
The Meter meters each packet and passes the packet and the metering result to the Marker: +------------+ | Result | | V +-------+ +--------+ | | | | Packet Stream ===>| Meter |===>| Marker |===> Marked Packet Stream | | | | +-------+ +--------+ The Meter operates in one of two modes. In the Color-Blind mode, the Meter assumes that the packet stream is uncolored. In the Color- Aware mode the Meter assumes that some preceding entity has pre- colored the incoming packet stream so that each packet is either green, yellow, or red. The details of the pre-coloring process, including handling of error scenarios, and how the Meter determines the color of a pre-colored packet are DS domain specific and outside the scope of this document. The Marker (re)colors an IP packet according to the results of the Meter. The color is coded in the DS field [RFC2474] of the packet in a PHB specific manner (see section 4 for an example). A companion document [RFC2697] describes another three color marker, called a Single Rate Three Color Maker (srTCM), where packets are marked based on a single rate and two burst sizes.
RFC2597], the color can be coded as the drop precedence of the packet.
[RFC2697] Heinanen, J. and R. Guerin, "A Single Rate Three Color Marker", RFC 2697, September 1999. [RFC2597] Heinanen, J., Baker, F., Weiss, W. and J. Wroclawski, "Assured Forwarding PHB Group", RFC 2597, June 1999. [RFC2474] Nichols, K., Blake, S., Baker, F. and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998. [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998.
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