4.3.3.5 Parameter Problem

A router MUST generate a Parameter Problem message for any error not specifically covered by another ICMP message. The IP header field or IP option including the byte indicated by the pointer field MUST be included unchanged in the IP header returned with this ICMP message. Section [4.3.2] defines an exception to this requirement.

A new variant of the Parameter Problem message was defined in [INTRO:2]:

Code 1 = required option is missing.

DISCUSSION

This variant is currently in use in the military community for a missing security option.