
Differentiated Services Field Codepoints (from RFC 2474)

(last updated 2002-03-27)

The DSCP field within the DS field is capable of conveying 64 distinct
codepoints.  The codepoint space is divided into three pools for the
purpose of codepoint assignment and management: a pool of 32
codepoints (Pool 1) to be assigned by Standards Action as defined in
[CONS], a pool of 16 codepoints (Pool 2) to be reserved for
experimental or Local Use (EXP/LU) as defined in [CONS], and a pool of
16 codepoints (Pool 3) which are initially available for experimental
or local use, but which should be preferentially utilized for
standardized assignments if Pool 1 is ever exhausted.  The pools are
defined in the following table (where 'x' refers to either '0' or
'1'):


Pool        Codepoint space          Assignment Policy    Reference
----        ---------------          -----------------    ---------	

 1            xxxxx0                 Standards Action     [RFC2474]
 2            xxxx11                 EXP/LU		  [RFC2474]
 3            xxxx01                 EXP/LU (*)           [RFC2474]


Pool 1 Codepoints (Guidelines from RFC2474)

	Name		Space			Reference
	----		-----			---------
	CS0		000000			[RFC2474]
	CS1		001000			[RFC2474]
	CS2		010000			[RFC2474]
	CS3		011000			[RFC2474]
	CS4		100000			[RFC2474]
	CS5		101000			[RFC2474]
	CS6		110000			[RFC2474]
	CS7		111000			[RFC2474]
	AF11		001010			[RFC2597]
	AF12		001100			[RFC2597]
	AF13		001110			[RFC2597]
	AF21		010010			[RFC2597]
	AF22		010100			[RFC2597]
	AF23		010110			[RFC2597]
	AF31		011010			[RFC2597]
	AF32		011100			[RFC2597]
	AF33		011110			[RFC2597]
	AF41		100010			[RFC2597]
	AF42		100100			[RFC2597]
	AF43		100110			[RFC2597]
	EF PHB		101110			[RFC3246]


References

[RFC2474]  Nichols, K., et. al., "Definition of the Differentiated
           Services Field (DS Field) in the IPv4 and IPv6 Headers", 
           RFC 2474, December 1998.

[RFC2597]  Heinanen, J., et. al., "Assured Forwarding PHB Group", 
           RFC 2597, June 1999.

[RFC3246]  B. Davie, A. Charny, J.C.R. Bennett, K. Benson, 
           J.Y. Le Boudec, W. Courtney, S. Davari, V. Firoiu, and
           D. Stiliadis, "An Expedited Forwarding PHB 
           (Per-Hop Behavior)", RFC 3246, March 2002.

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