6. IANA Considerations
This document defines the DS field in the IPv4 TOS octet and the IPv6 Traffic Class octet, and the allocation policy in various PHB specifications for controlling the assignment of particular codepoints in the DS field for selecting particular PHBs.
Prior to the publication of this specification, the use of the IPv4 TOS octet was administered by the IANA under a combination of standards and other operational history specifications [RFC791, RFC1349, RFC1812]. This document changes how the IANA administers this field, and after this document takes effect, the text in [RFC791], [RFC1122], [RFC1349], and [RFC1812] relating to the use of the IPv4 TOS octet or the IP Precedence field becomes obsolete.
This document allocates eight codepoints in its backwards compatibility section (Sec. 4), and allocates another 32 codepoints here for standards action use.
6.1 Standards Action Codepoint and PHB Definition
Pool 1 codepoints are assigned by Standards Action as defined in [RFC2434]. Pool 1 codepoints are DSCP values of the form xxxxx0, where x may be either 0 or 1.
Pool 1 codepoints MUST be assigned through standards-track RFCs which MUST fully define a specific PHB, or a set of PHBs, according to the guidelines in [ARCH], including the technical specification for the PHB and its intended use.
The RECOMMENDED value of a codepoint SHOULD be specified from Pool 1, but the standards organization MUST NOT choose any value of the form 11x000 (those codepoints are reserved for network and internet control traffic; see Sec. 4.2.2.2). The standards organization MAY circumvent this rule by using codepoints from Pool 3 (Experimental/Local Use codepoints; see Sec. 6.3) during experimentation and testing. Once the PHB is sufficiently mature and is accepted by the IETF as a standards-track RFC, IANA will permanently assign a recommended codepoint from Pool 1, and the Pool 3 allocation table MUST be updated to reflect that it can no longer be used for that PHB on a provisional basis. Since there are only 32 codepoints in Pool 1, care MUST be taken to reserve Pool 1 for those PHBs (or PHB groups) that are well-defined and widely recognized.
6.2 Experimental or Local Use PHBs
Pool 3 is the pool of codepoints that are reserved for experimental or local use PHBs. Pool 3 codepoints are of the form DSCP values xxxx11, where x may be either 0 or 1. Pool 3 codepoints MAY be utilized for experimental or local use PHBs without IANA approval.
Experimental use includes any experimentation, testing, or development work on PHBs, regardless of their status, including standards-track experimentation. Since other networks may be using the same codepoints for different experimental or local use PHBs, there SHOULD NOT be any assumption that the use of these codepoints has any form of uniform meaning globally.
Use of Pool 3 SHOULD be documented in an RFC, but such RFCs are not required to have IETF consensus and need not be standards-track. The mapping of codepoints to PHBs in this pool MAY be configured locally. It may be useful to publish Informational RFCs documenting experimental PHBs and their recommended Pool 3 codepoints to assist in the coordination of widespread testing efforts for PHBs based on different implementations.
To track current use of Pool 3 codepoint assignments (during the period of becoming a standard, or transitioning from experimental to local use), IANA SHOULD establish a publicly available registry listing Pool 3 codepoint allocations, including references to relevant specifications.
6.3 Reserved Codepoints
Pool 2 DSCP values of the form xxxx01, where x may be either 0 or 1, are reserved for future standards action allocation by IANA. Codepoints in this pool SHOULD NOT be used for experimentation or testing of PHBs unless in a completely controlled environment.