As per Relevance of the word september, we have this rfc below:
Network Working Group J.
Request for Comments: 2698 Telia
Category: Informational R.
University of
September 1999
A Two Rate Three Color
Status of this
This memo provides information for the Internet community. It
not specify an Internet standard of any kind. Distribution of
memo is unlimited
Copyright
Copyright (C) The Internet Society (1999). All Rights Reserved
This document defines a Two Rate Three Color Marker (trTCM),
can be used as a component in a Diffserv traffic
[RFC2475, RFC2474]. The trTCM meters an IP packet stream and
its packets based on two rates, Peak Information Rate (PIR)
Committed Information Rate (CIR), and their associated burst sizes
be either green, yellow, or red. A packet is marked red if
exceeds the PIR. Otherwise it is marked either yellow or
depending on whether it exceeds or doesn't exceed the CIR
1.
The Two Rate Three Color Marker (trTCM) meters an IP packet
and marks its packets either green, yellow, or red. A packet
marked red if it exceeds the Peak Information Rate (PIR).
it is marked either yellow or green depending on whether it
or doesn't exceed the Committed Information Rate (CIR). The trTCM
useful, for example, for ingress policing of a service, where a
rate needs to be enforced separately from a committed rate
Heinanen & Guerin Informational [Page 1]
RFC 2698 A Two Rate Three Color Marker September 1999
The Meter meters each packet and passes the packet and the
result to the Marker
+------------+
| Result |
|
+-------+ +--------+
| | | |
Packet Stream ===>| Meter |===>| Marker |===> Marked Packet
| | | |
+-------+ +--------+
The Meter operates in one of two modes. In the Color-Blind mode,
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
green, yellow, or red. The details of the pre-coloring process
including handling of error scenarios, and how the Meter
the color of a pre-colored packet are DS domain specific and
the scope of this document
The Marker (re)colors an IP packet according to the results of
Meter. The color is coded in the DS field [RFC2474] of the packet
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
marked based on a single rate and two burst sizes
2.
The trTCM is configured by setting its mode and by assigning
to four traffic parameters: a Peak Information Rate (PIR) and
associated Peak Burst Size (PBS) and a Committed Information
(CIR) and its associated Committed Burst Size (CBS).
The PIR and CIR are measured in bytes of IP packets per second, i.e.,
it includes the IP header, but not link specific headers. The
must be equal to or greater than the CIR
The PBS and the CBS and are measured in bytes and both of them
be configured to be greater than 0. It is recommended that they
configured to be equal to or greater than the size of the
possible IP packet in the stream
Heinanen & Guerin Informational [Page 2]
RFC 2698 A Two Rate Three Color Marker September 1999
3.
The behavior of the Meter is specified in terms of its mode and
token buckets, P and C, with rates PIR and CIR, respectively.
maximum size of the token bucket P is PBS and the maximum size of
token bucket C is CBS
The token buckets P and C are initially (at time 0) full, i.e.,
token count Tp(0) = PBS and the token count Tc(0) = CBS. Thereafter
the token count Tp is incremented by one PIR times per second up
PBS and the token count Tc is incremented by one CIR times per
up to CBS
When a packet of size B bytes arrives at time t, the
happens if the trTCM is configured to operate in the Color-
mode
o If Tp(t)-B < 0, the packet is red,
o if Tc(t)-B < 0, the packet is yellow and Tp is decremented by B
o the packet is green and both Tp and Tc are decremented by B
When a packet of size B bytes arrives at time t, the
happens if the trTCM is configured to operate in the Color-
mode
o If the packet has been precolored as red or if Tp(t)-B < 0,
packet is red,
o if the packet has been precolored as yellow or if Tc(t)-B < 0,
the packet is yellow and Tp is decremented by B,
o the packet is green and both Tp and Tc are decremented by B
The actual implementation of a Meter doesn't need to be
according to the above formal specification
4.
The Marker reflects the metering result by setting the DS field
the packet to a particular codepoint. In case of the AF
[RFC2597], the color can be coded as the drop precedence of
packet
Heinanen & Guerin Informational [Page 3]
RFC 2698 A Two Rate Three Color Marker September 1999
5. Service
The trTCM can be used to mark a IP packet stream in a service,
different, decreasing levels of assurances (either absolute
relative) are given to packets which are green, yellow, or red.
example, a service may discard all red packets, because they
the peak rate, forward yellow packets as best effort, and
green packets with a low drop probability
6. Security
The trTCM has no known security concerns
7.
[RFC2697] Heinanen, J. and R. Guerin, "A Single Rate Three
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 (
Field) in the IPv4 and IPv6 Headers", RFC 2474,
1998.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang,
and W. Weiss, "An Architecture for
Services", RFC 2475, December 1998.
8. Authors'
Juha
Telia Finland, Inc
Myyrmaentie 2
01600 Vantaa,
EMail: jh@telia.
Roch
University of
Department of Electrical Engineering, Rm 367
200 South 33rd
Philadelphia, PA 19104
EMail: guerin@ee.upenn.
Heinanen & Guerin Informational [Page 4]
RFC 2698 A Two Rate Three Color Marker September 1999
9. Full Copyright
Copyright (C) The Internet Society (1999). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Funding for the RFC Editor function is currently provided by
Internet Society
Heinanen & Guerin Informational [Page 5]
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