requirement
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This document is one of a pair that defines and discusses the
requirements for host system implementations of the Internet protocol
suite. This RFC covers the communication protocol layers: link
layer ...
... IP layer, and transport layer. Its companion RFC,
"Requirements for Internet Hosts -- Application and Support"
...
... application layer protocols. This document
should also be read in conjunction with "Requirements for Internet
Gateways ...
...
For each protocol, this document also contains an explicit set of
requirements, recommendations, and options. The reader must
understand that the list of requirements in this document is
...
... For each protocol, this document also contains an explicit set of
requirements, recommendations, and options. The reader must
understand that the list of requirements in this document is
incomplete by itself; the complete set of requirements for an
...
... understand that the list of requirements in this document is
incomplete by itself; the complete set of requirements for an
Internet host ...
... Internet technical community, and that followed good communications
software engineering practices, should differ from the requirements
of this document in only minor ways. Thus, in many cases, the
"requirements ...
... requirements
of this document in only minor ways. Thus, in many cases, the
"requirements" in this RFC are already stated or implied in the
standard protocol documents, so that their inclusion here is, in a
...
... This document includes discussion and explanation of many of the
requirements and recommendations. A simple list of requirements
would be dangerous, because:
...
... discussion and explanation of many of the
requirements and recommendations. A simple list of requirements
would be dangerous, because:
...
... diversity and complexity of the Internet system. Although most
current implementations fail to meet these requirements in various
ways, some minor and some major, this specification is the ideal
towards which we need to move.
...
...
These requirements are based on the current level of Internet
architecture. This document will be updated as required to provide
additional clarifications or to include additional information in
...
... host software.
The requirements spelled out in this document are designed
for a full-function Internet host ...
... service directly
to users, and support protocols that provide common system
functions. Requirements for user and support protocols
will be found in the companion RFC [INTRO:1].
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...
Such dual-purpose systems must follow the Gateway Requirements
RFC [INTRO:2] with respect to their gateway ...
...
At many points in this document, you will find a requirement
that a parameter be a configurable option. There are several
different reasons behind such requirements ...
... requirement
that a parameter be a configurable option. There are several
different reasons behind such requirements. In a few cases,
there is current uncertainty or disagreement about the best
value, and it may be necessary to update ...
... unavailable and may be insufficient. In some cases,
configurability is needed because of administrative
requirements.
...
... configuration file is only necessary to override those defaults
that are inappropriate in a particular installation. Thus, the
configurability requirement is an assurance that it will be
POSSIBLE to override the default when necessary, even in a
binary-only or ROM-based product.
...
... that an implementation does strictly mirror the layering of the
protocols. Thus, the following three major sections specify
the requirements for the link layer, the internet layer ...
... Protocol Walk-Through -- considers the protocol
specification documents section-by-section, correcting
errors, stating requirements that may be ambiguous or
ill-defined, and providing further clarification or
explanation. ...
... Summmary -- contains a summary of the requirements of the
section. ...
... DISCUSSION" or
"IMPLEMENTATION". This material is intended to give
clarification and explanation of the preceding requirements
text. It also includes some suggestions on possible future
directions or developments. The implementation material
...
... Requirements ...
...
In this document, the words that are used to define the
significance of each particular requirement are capitalized.
...
...
This word or the adjective "REQUIRED" means that the item
is an absolute requirement of the specification.
* "SHOULD"
...
...
An implementation is not compliant if it fails to satisfy one
or more of the MUST requirements for the protocols it
implements. An implementation that satisfies all the MUST and
all the SHOULD requirements ...
... requirements for the protocols it
implements. An implementation that satisfies all the MUST and
all the SHOULD requirements for its protocols is said to be
"unconditionally compliant"; one that satisfies all the MUST
requirements ...
... requirements for its protocols is said to be
"unconditionally compliant"; one that satisfies all the MUST
requirements but not all the SHOULD requirements for its
protocols is said to be "conditionally compliant".
...
... "unconditionally compliant"; one that satisfies all the MUST
requirements but not all the SHOULD requirements for its
protocols is said to be "conditionally compliant".
...
... vendors, and government agencies.
It was assembled primarily by the Host Requirements Working Group
of the Internet Engineering Task Force ...
... hosts and gateways, have the same
requirements for link layer protocols. These requirements are
...
... requirements for link layer protocols. These requirements are
given in Chapter 3 of "Requirements for Internet ...
... link layer protocols. These requirements are
given in Chapter 3 of "Requirements for Internet Gateways"
...
... LINK LAYER REQUIREMENTS SUMMARY ...
... gateway and MUST also meet the specifications laid out
in the gateway requirements RFC [INTRO:2]. An Internet host ...
... host support
reassembly. See Sections 3.3.2 and 3.3.3 for the
requirements on fragmentation and reassembly.
...
... algorithms. See Section 2 of [INTRO:1] for
the requirements on application programs to specify TOS
values.
...
...
Here are the requirements for specific IP options:
...
... Security option in every
datagram; such a requirement is outside the scope of
this document and the IP standard specification. Note,
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...
NOTE: THESE RESTRICTIONS TAKE PRECEDENCE OVER ANY REQUIREMENT
ELSEWHERE IN THIS DOCUMENT FOR SENDING ICMP ERROR MESSAGES ...
... Multihoming Requirements ...
... Sections 4.1.3.5 and 4.2.3.7 and the "General Issues"
section of [INTRO:1] for more specific requirements on
higher layers.
...
...
There are two key requirement issues related to multihoming:
...
... (1) Only if feature is implemented.
(2) This requirement is overruled if datagram is an ICMP error message.
...
... UDP REQUIREMENTS SUMMARY ...
... service
(Telnet); requirements for these application-layer protocols
are described in [INTRO:1 ...
... TCP REQUIREMENT SUMMARY ...
... Hosts -- Application and Support," IETF Host Requirements Working Group, R. Braden, Ed., RFC-1123std3, October 1989. ...