
Differentiated Services Field Codepoints (from RFC 2474)

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
RECOMMENDED 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]


References

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