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ICMP Overview, History, Versions and Standards
(Page 2 of 3)
ICMP Standards for IPv4 and IPv6
The defining standard I just quoted,
by the way, is RFC 792. This was the initial defining standard for ICMP,
titled simply Internet Control Message Protocol. It was
published at the same time as the standard for IP, which was RFC 791.
This is further indication that IP and ICMP really are a team
Due to the close relationship between
the two, when the new
version 6 of the Internet Protocol (IPv6)
was developed in the mid-1990s, it was necessary to define a new version
of ICMP as well. This was of course called the Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6)
Specification, first published as RFC 1885 in 1995, and revised
in RFC 2463 in 1998. Just as the original IP is now often called IPv4
to differentiate it from IPv6, the original ICMP is now also called
These two RFCs, 792 and 2463, define
the basic operation of ICMPv4 and ICMPv6 respectively, and also describe
some of the ICMP message types supported by each version of the protocol.
ICMPv4 and ICMPv6 are very similar in most general respects, though
they have some differences, most of which are a direct result of the
changes made to IP itself. Another document, RFC 1122 (Requirements
for Internet Hosts - Communication Layers) contains rules for
how ICMPv4 is used, as we will see in the
topic on ICMP message creation and processing conventions.
RFC 1812 (Requirements for IP Version 4 Routers) is also
Key Concept: In TCP/IP, diagnostic, test and error-reporting functions at the internet/network layer are performed by the Internet Control Message Protocol (ICMP), which is like the Internet Protocols administrative assistant. The original version, now called ICMPv4, is used with IPv4, and the newer ICMPv6 with IPv6.
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The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005
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