RFC 2780 (rfc2780) - Page 2 of 10

IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers

RFC 2780                    IANA Assignments                  March 2000


2. Temporary Assignments

   From time to time temporary assignments are made in the values for
   fields in these headers for use in experiments.  IESG Approval is
   required for any such temporary assignments.

3. Version field in the IP header.

   The first field in the IP header of all current versions of IP is the
   Version field.  New values in the Version field define new versions
   of the IP protocol and are allocated only after an IETF Standards
   Action.  It should be noted that some of the Version number bits are
   used by TCP/IP header compression schemes. Specifically, the hi-order
   bit of the Version field is also used by TCP/IP header compression
   [HC], while the three hi-order bits are used by IP Header Compression
   [IPHC].

4. IANA Considerations for fields in the IPv4 header

   The IPv4 header [V4] contains the following fields that carry values
   assigned by the IANA: Version, Type of Service, Protocol, Source
   Address, Destination Address, and Option Type.

4.1 IPv4 IP Version field

   The IPv4 Version field is always 4.

4.2 IPv4 Type of Service field

   The Type of Service field described in [V4] has been superseded[DIFF]
   by the 6-bit Differentiated Services (DS) field and a 2-bit field
   which is currently reserved.  The IANA allocates values in the DS
   field following the IANA Considerations section in [DIFF].  [ECN]
   describes an experimental use of the 2-bit "currently unused" field.
   Other experimental uses of this field may be assigned after IESG
   Approval processes.  Permanent values in this field are allocated
   following a Standards Action process.

4.3 IPv4 Protocol field

   IANA allocates values from the IPv4 Protocol name space following an
   Expert Review, IESG Approval or Standards Action process.  The Expert
   Review process should only be used in those special cases where non-
   disclosure information is involved.  In these cases the expert(s)
   should be designated by the IESG.






Bradner & Paxson         Best Current Practice