Formally Deprecating Some IPv4 Options
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A number of IPv4 options became obsolete in practice but were never formally deprecated. This document formalizes their deprecation to clean up the IANA 'IP OPTION NUMBERS' registry, providing a clear authoritative signal to implementers.
The Extended Internet Protocol (EIP) option, originally defined in RFC 1385, is superseded by IPv6 (RFC 2460). Implementations seeking EIP-like extended addressing should use IPv6 instead.
The MTU Probe (MTUP, value 11) and MTU Reply (MTUR, value 12) options were initially defined in RFC 1063 and had already been deprecated prior to this document by RFC 1191.
Per this document, the RFC Editor changed the status of RFC 1385, RFC 1393, RFC 1475, and RFC 1770 to Historic, reflecting that the IP options they define are no longer in use.
The Address Extension option (ADDEXT, type value 147, copy=1, class=0, number=19) is deprecated. It is defined in Experimental RFC 1475 as part of IPv7 (TP/IX), which was never widely deployed.
The Dynamic Packet State option (DPS, type value 151, copy=1, class=0, number=23) is deprecated. It was specified in a document intended to be published as Experimental that never became an RFC, and the option was never widely deployed.
The ENCODE option (type value 15, copy=0, class=0, number=15) is deprecated. It was used for experimentation around IP-layer encryption; no products are known to have ever shipped with support for it.
The Extended Internet Protocol option (EIP, type value 145, copy=1, class=0, number=17) is deprecated. It was defined in RFC 1385 and superseded by IPv6 (RFC 2460).
The Selective Directed Broadcast option (SDB, type value 149, copy=1, class=0, number=21) is deprecated. It was originally defined in RFC 1770, was never widely deployed, and the approach was abandoned.
The Stream ID option (SID, type value 136, copy=1, class=0, number=8) is deprecated. It was specified in RFC 791 and already deprecated in RFC 1122 Section 3.2.1.8 and RFC 1812 Section 4.2.2.1.
The Traceroute option (TR, type value 82, copy=0, class=2, number=18) is deprecated. It was defined as Experimental in RFC 1393 and was never widely deployed on the public Internet.
The Upstream Multicast Packet option (UMP, type value 152, copy=1, class=0, number=24) is deprecated. Its use was deprecated by RFC 5015, which employs a control-plane mechanism for upstream forwarding of multicast packets on multi-access LANs.
The VISA option (type value 142, copy=1, class=0, number=14) is deprecated. It was part of a USC experiment involving inter-organizational network security and was never widely deployed.
IANA has marked nine IPv4 options as deprecated in the 'IP OPTION NUMBERS' registry. The registry denotes a deprecated IP Option Number by marking it with a footnote.
This document does not modify the security properties of the IPv4 options being deprecated. The formal deprecation is an administrative action and introduces no new security risks or mitigations.