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Network Working Group Internet Architecture Board
Request for Comments: 1720 J. Postel, Editor
Obsoletes: RFCs 1610, 1600, 1540, 1500, November 1994
1410, 1360, 1280, 1250, 1100, 1083,
1130, 1140, 1200
STD: 1
Category: Standards Track


INTERNET OFFICIAL PROTOCOL STANDARDS


Status of this Memo

This memo describes the state of standardization of protocols used in
the Internet as determined by the Internet Architecture Board (IAB).
This memo is an Internet Standard. Distribution of this memo is
unlimited.

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1. The Standardization Process . . . . . . . . . . . . . . . . 3
2. The Request for Comments Documents . . . . . . . . . . . . . 5
3. Other Reference Documents . . . . . . . . . . . . . . . . . 6
3.1. Assigned Numbers . . . . . . . . . . . . . . . . . . . . . 6
3.2. Gateway Requirements . . . . . . . . . . . . . . . . . . . 6
3.3. Host Requirements . . . . . . . . . . . . . . . . . . . . 6
3.4. The MIL-STD Documents . . . . . . . . . . . . . . . . . . 6
4. Explanation of Terms . . . . . . . . . . . . . . . . . . . . 7
4.1. Definitions of Protocol State (Maturity Level) . . . . . . 8
4.1.1. Standard Protocol . . . . . . . . . . . . . . . . . . . 8
4.1.2. Draft Standard Protocol . . . . . . . . . . . . . . . . 9
4.1.3. Proposed Standard Protocol . . . . . . . . . . . . . . . 9
4.1.4. Experimental Protocol . . . . . . . . . . . . . . . . . 9
4.1.5. Informational Protocol . . . . . . . . . . . . . . . . . 9
4.1.6. Historic Protocol . . . . . . . . . . . . . . . . . . . 9
4.2. Definitions of Protocol Status (Requirement Level) . . . 9
4.2.1. Required Protocol . . . . . . . . . . . . . . . . . . 10
4.2.2. Recommended Protocol . . . . . . . . . . . . . . . . . 10
4.2.3. Elective Protocol . . . . . . . . . . . . . . . . . . 10
4.2.4. Limited Use Protocol . . . . . . . . . . . . . . . . . 10
4.2.5. Not Recommended Protocol . . . . . . . . . . . . . . . 10
5. The Standards Track . . . . . . . . . . . . . . . . . . . 10
5.1. The RFC Processing Decision Table . . . . . . . . . . . 10
5.2. The Standards Track Diagram . . . . . . . . . . . . . . 12
6. The Protocols . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Recent Changes . . . . . . . . . . . . . . . . . . . . . 14



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6.1.1. New RFCs . . . . . . . . . . . . . . . . . . . . . . . 14
6.1.2. Other Changes . . . . . . . . . . . . . . . . . . . . 23
6.2. Standard Protocols . . . . . . . . . . . . . . . . . . . 24
6.3. Network-Specific Standard Protocols . . . . . . . . . . 26
6.4. Draft Standard Protocols . . . . . . . . . . . . . . . . 27
6.5. Proposed Standard Protocols . . . . . . . . . . . . . . 28
6.6. Telnet Options . . . . . . . . . . . . . . . . . . . . . 31
6.7. Experimental Protocols . . . . . . . . . . . . . . . . . 32
6.8. Informational Protocols . . . . . . . . . . . . . . . . 33
6.9. Historic Protocols . . . . . . . . . . . . . . . . . . . 34
6.10 Obsolete Protocols . . . . . . . . . . . . . . . . . . . 36
7. Contacts . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.1. IAB, IETF, and IRTF Contacts . . . . . . . . . . . . . . 37
7.1.1. Internet Architecture Board (IAB) Contact . . . . . . 37
7.1.2. Internet Engineering Task Force (IETF) Contact . . . . 38
7.1.3. Internet Research Task Force (IRTF) Contact . . . . . 39
7.2. Internet Assigned Numbers Authority (IANA) Contact . . . 39
7.3. Request for Comments Editor Contact . . . . . . . . . . 40
7.4. Network Information Center Contact . . . . . . . . . . . 40
7.5. Sources for Requests for Comments . . . . . . . . . . . 41
8. Security Considerations . . . . . . . . . . . . . . . . . 41
9. Author's Address . . . . . . . . . . . . . . . . . . . . . 41

Introduction

A discussion of the standardization process and the RFC document
series is presented first, followed by an explanation of the terms.
Sections 6.2 - 6.10 contain the lists of protocols in each stage of
standardization. Finally are pointers to references and contacts for
further information.

This memo is intended to be issued approximately quarterly; please be
sure the copy you are reading is current. Current copies may be
obtained from the Network Information Center (INTERNIC) or from the
Internet Assigned Numbers Authority (IANA) (see the contact
information at the end of this memo). Do not use this edition after
1-Mar-95.

See Section 6.1 for a description of recent changes. In the official
lists in sections 6.2 - 6.10, an asterisk (*) next to a protocol
denotes that it is new to this document or has been moved from one
protocol level to another, or differs from the previous edition of
this document.








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1. The Standardization Process

The Internet Architecture Board maintains this list of documents that
define standards for the Internet protocol suite. See RFC-1601 for
the charter of the IAB and RFC-1160 for an explanation of the role
and organization of the IAB and its subsidiary groups, the Internet
Engineering Task Force (IETF) and the Internet Research Task Force
(IRTF). Each of these groups has a steering group called the IESG
and IRSG, respectively. The IETF develops these standards with the
goal of co-ordinating the evolution of the Internet protocols; this
co-ordination has become quite important as the Internet protocols
are increasingly in general commercial use. The definitive
description of the Internet standards process is found in RFC-1602.

The majority of Internet protocol development and standardization
activity takes place in the working groups of the IETF.

Protocols which are to become standards in the Internet go through a
series of states or maturity levels (proposed standard, draft
standard, and standard) involving increasing amounts of scrutiny and
testing. When a protocol completes this process it is assigned a STD
number (see RFC-1311). At each step, the Internet Engineering
Steering Group (IESG) of the IETF must make a recommendation for
advancement of the protocol.

To allow time for the Internet community to consider and react to
standardization proposals, a minimum delay of 6 months before a
proposed standard can be advanced to a draft standard and 4 months
before a draft standard can be promoted to standard.

It is general practice that no proposed standard can be promoted to
draft standard without at least two independent implementations (and
the recommendation of the IESG). Promotion from draft standard to
standard generally requires operational experience and demonstrated
interoperability of two or more implementations (and the
recommendation of the IESG).

In cases where there is uncertainty as to the proper decision
concerning a protocol a special review committee may be appointed
consisting of experts from the IETF, IRTF and the IAB with the
purpose of recommending an explicit action.

Advancement of a protocol to proposed standard is an important step
since it marks a protocol as a candidate for eventual standardization
(it puts the protocol "on the standards track"). Advancement to
draft standard is a major step which warns the community that, unless
major objections are raised or flaws are discovered, the protocol is
likely to be advanced to standard in six months.



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Some protocols have been superseded by better ones or are otherwise
unused. Such protocols are still documented in this memorandum with
the designation "historic".

Because it is useful to document the results of early protocol
research and development work, some of the RFCs document protocols
which are still in an experimental condition. The protocols are
designated "experimental" in this memorandum. They appear in this
report as a convenience to the community and not as evidence of their
standardization.

Other protocols, such as those developed by other standards
organizations, or by particular vendors, may be of interest or may be
recommended for use in the Internet. The specifications of such
protocols may be published as RFCs for the convenience of the
Internet community. These protocols are labeled "informational" in
this memorandum.

In addition to the working groups of the IETF, protocol development
and experimentation may take place as a result of the work of the
research groups of the Internet Research Task Force, or the work of
other individuals interested in Internet protocol development. The
the documentation of such experimental work in the RFC series is
encouraged, but none of this work is considered to be on the track
for standardization until the IESG has made a recommendation to
advance the protocol to the proposed standard state.

A few protocols have achieved widespread implementation without the
approval of the IESG. For example, some vendor protocols have become
very important to the Internet community even though they have not
been recommended by the IESG. However, the IAB strongly recommends
that the standards process be used in the evolution of the protocol
suite to maximize interoperability (and to prevent incompatible
protocol requirements from arising). The use of the terms
"standard", "draft standard", and "proposed standard" are reserved in
any RFC or other publication of Internet protocols to only those
protocols which the IESG has approved.

In addition to a state (like "Proposed Standard"), a protocol is also
assigned a status, or requirement level, in this document. The
possible requirement levels ("Required", "Recommended", "Elective",
"Limited Use", and "Not Recommended") are defined in Section 4.2.
When a protocol is on the standards track, that is in the proposed
standard, draft standard, or standard state (see Section 5), the
status shown in Section 6 is the current status.

Few protocols are required to be implemented in all systems; this is
because there is such a variety of possible systems, for example,



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gateways, routers, terminal servers, workstations, and multi-user
hosts. The requirement level shown in this document is only a one
word label, which may not be sufficient to characterize the
implementation requirements for a protocol in all situations. For
some protocols, this document contains an additional status paragraph
(an applicability statement). In addition, more detailed status
information may be contained in separate requirements documents (see
Section 3).

2. The Request for Comments Documents

The documents called Request for Comments (or RFCs) are the working
notes of the "Network Working Group", that is the Internet research
and development community. A document in this series may be on
essentially any topic related to computer communication, and may be
anything from a meeting report to the specification of a standard.

Notice:

All standards are published as RFCs, but not all RFCs specify
standards.

Anyone can submit a document for publication as an RFC. Submissions
must be made via electronic mail to the RFC Editor (see the contact
information at the end of this memo, and see RFC 1543).

While RFCs are not refereed publications, they do receive technical
review from the task forces, individual technical experts, or the RFC
Editor, as appropriate.

The RFC series comprises a wide range of documents, ranging from
informational documents of general interests to specifications of
standard Internet protocols. In cases where submission is intended
to document a proposed standard, draft standard, or standard
protocol, the RFC Editor will publish the document only with the
approval of the IESG. For documents describing experimental work,
the RFC Editor will notify the IESG before publication, allowing for
the possibility of review by the relevant IETF working group or IRTF
research group and provide those comments to the author. See Section
5.1 for more detail.

Once a document is assigned an RFC number and published, that RFC is
never revised or re-issued with the same number. There is never a
question of having the most recent version of a particular RFC.
However, a protocol (such as File Transfer Protocol (FTP)) may be
improved and re-documented many times in several different RFCs. It
is important to verify that you have the most recent RFC on a
particular protocol. This "Internet Official Protocol Standards"



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memo is the reference for determining the correct RFC for the current
specification of each protocol.

The RFCs are available from the INTERNIC, and a number of other
sites. For more information about obtaining RFCs, see Sections 7.4
and 7.5.

3. Other Reference Documents

There are three other reference documents of interest in checking the
current status of protocol specifications and standardization. These
are the Assigned Numbers, the Gateway Requirements, and the Host
Requirements. Note that these documents are revised and updated at
different times; in case of differences between these documents, the
most recent must prevail.

Also, one should be aware of the MIL-STD publications on IP, TCP,
Telnet, FTP, and SMTP. These are described in Section 3.4.

3.1. Assigned Numbers

The "Assigned Numbers" document lists the assigned values of the
parameters used in the various protocols. For example, IP protocol
codes, TCP port numbers, Telnet Option Codes, ARP hardware types, and
Terminal Type names. Assigned Numbers was most recently issued as
RFC-1700.

3.2. Gateway Requirements

This document reviews the specifications that apply to gateways and
supplies guidance and clarification for any ambiguities. Gateway
Requirements is RFC-1009. A working group of the IETF is actively
preparing a revision.

3.3. Host Requirements

This pair of documents reviews and updates the specifications that
apply to hosts, and it supplies guidance and clarification for any
ambiguities. Host Requirements was issued as RFC-1122 and RFC-1123.

3.4. The MIL-STD Documents

The Internet community specifications for IP (RFC-791) and TCP (RFC-
793) and the DoD MIL-STD specifications are intended to describe
exactly the same protocols. Any difference in the protocols
specified by these sets of documents should be reported to DISA and
to the IESG. The RFCs and the MIL-STDs for IP and TCP differ in
style and level of detail. It is strongly advised that the two sets



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of documents be used together, along with RFC-1122 and RFC-1123.

The Internet and the DoD MIL-STD specifications for the FTP, SMTP,
and Telnet protocols are essentially the same documents (RFCs 765,
821, 854). The MIL-STD versions have been edited slightly. Note
that the current Internet specification for FTP is RFC-959 (as
modified by RFC-1123).

Note that these MIL-STD are now somewhat out of date. The Gateway
Requirements (RFC-1009) and Host Requirements (RFC-1122, RFC-1123)
take precedence over both earlier RFCs and the MIL-STDs.

Internet Protocol (IP) MIL-STD-1777
Transmission Control Protocol (TCP) MIL-STD-1778
File Transfer Protocol (FTP) MIL-STD-1780
Simple Mail Transfer Protocol (SMTP) MIL-STD-1781
Telnet Protocol and Options (TELNET) MIL-STD-1782

These documents are available from the Naval Publications and Forms
Center. Requests can be initiated by telephone, telegraph, or mail;
however, it is preferred that private industry use form DD1425, if
possible.

Naval Publications and Forms Center, Code 3015
5801 Tabor Ave
Philadelphia, PA 19120
Phone: 1-215-697-3321 (order tape)
1-215-697-4834 (conversation)

4. Explanation of Terms

There are two independent categorization of protocols. The first is
the "maturity level" or STATE of standardization, one of "standard",
"draft standard", "proposed standard", "experimental",
"informational" or "historic". The second is the "requirement level"
or STATUS of this protocol, one of "required", "recommended",
"elective", "limited use", or "not recommended".

The status or requirement level is difficult to portray in a one word
label. These status labels should be considered only as an
indication, and a further description, or applicability statement,
should be consulted.

When a protocol is advanced to proposed standard or draft standard,
it is labeled with a current status.






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At any given time a protocol occupies a cell of the following matrix.
Protocols are likely to be in cells in about the following
proportions (indicated by the relative number of Xs). A new protocol
is most likely to start in the (proposed standard, elective) cell, or
the (experimental, not recommended) cell.

S T A T U S
Req Rec Ele Lim Not
+-----+-----+-----+-----+-----+
Std | X | XXX | XXX | | |
S +-----+-----+-----+-----+-----+
Draft | X | X | XXX | | |
T +-----+-----+-----+-----+-----+
Prop | | X | XXX | | |
A +-----+-----+-----+-----+-----+
Info | | | | | |
T +-----+-----+-----+-----+-----+
Expr | | | | XXX | |
E +-----+-----+-----+-----+-----+
Hist | | | | | XXX |
+-----+-----+-----+-----+-----+

What is a "system"?

Some protocols are particular to hosts and some to gateways; a few
protocols are used in both. The definitions of the terms below
will refer to a "system" which is either a host or a gateway (or
both). It should be clear from the context of the particular
protocol which types of systems are intended.

4.1. Definitions of Protocol State

Every protocol listed in this document is assigned to a "maturity
level" or STATE of standardization: "standard", "draft standard",
"proposed standard", "experimental", or "historic".

4.1.1. Standard Protocol

The IESG has established this as an official standard protocol for
the Internet. These protocols are assigned STD numbers (see RFC-
1311). These are separated into two groups: (1) IP protocol and
above, protocols that apply to the whole Internet; and (2)
network-specific protocols, generally specifications of how to do
IP on particular types of networks.







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4.1.2. Draft Standard Protocol

The IESG is actively considering this protocol as a possible
Standard Protocol. Substantial and widespread testing and comment
are desired. Comments and test results should be submitted to the
IESG. There is a possibility that changes will be made in a Draft
Standard Protocol before it becomes a Standard Protocol.

4.1.3. Proposed Standard Protocol

These are protocol proposals that may be considered by the IESG
for standardization in the future. Implementation and testing by
several groups is desirable. Revision of the protocol
specification is likely.

4.1.4. Experimental Protocol

A system should not implement an experimental protocol unless it
is participating in the experiment and has coordinated its use of
the protocol with the developer of the protocol.

Typically, experimental protocols are those that are developed as
part of an ongoing research project not related to an operational
service offering. While they may be proposed as a service
protocol at a later stage, and thus become proposed standard,
draft standard, and then standard protocols, the designation of a
protocol as experimental may sometimes be meant to suggest that
the protocol, although perhaps mature, is not intended for
operational use.

4.1.5. Informational Protocol

Protocols developed by other standard organizations, or vendors,
or that are for other reasons outside the purview of the IESG, may
be published as RFCs for the convenience of the Internet community
as informational protocols.

4.1.6. Historic Protocol

These are protocols that are unlikely to ever become standards in
the Internet either because they have been superseded by later
developments or due to lack of interest.

4.2. Definitions of Protocol Status

This document lists a "requirement level" or STATUS for each
protocol. The status is one of "required", "recommended",
"elective", "limited use", or "not recommended".



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4.2.1. Required Protocol

A system must implement the required protocols.

4.2.2. Recommended Protocol

A system should implement the recommended protocols.

4.2.3. Elective Protocol

A system may or may not implement an elective protocol. The
general notion is that if you are going to do something like this,
you must do exactly this. There may be several elective protocols
in a general area, for example, there are several electronic mail
protocols, and several routing protocols.

4.2.4. Limited Use Protocol

These protocols are for use in limited circumstances. This may be
because of their experimental state, specialized nature, limited
functionality, or historic state.

4.2.5. Not Recommended Protocol

These protocols are not recommended for general use. This may be
because of their limited functionality, specialized nature, or
experimental or historic state.

5. The Standards Track

This section discusses in more detail the procedures used by the RFC
Editor and the IESG in making decisions about the labeling and
publishing of protocols as standards.

5.1. The RFC Processing Decision Table

Here is the current decision table for processing submissions by the
RFC Editor. The processing depends on who submitted it, and the
status they want it to have.












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+==========================================================+
|**************| S O U R C E |
+==========================================================+
| Desired | IAB | IESG | IRSG | Other |
| Status | | | | |
+==========================================================+
| | | | | |
| Standard | Bogus | Publish | Bogus | Bogus |
| or | (2) | (1) | (2) | (2) |
| Draft | | | | |
| Standard | | | | |
+--------------+----------+----------+----------+----------+
| | | | | |
| | Refer | Publish | Refer | Refer |
| Proposed | (3) | (1) | (3) | (3) |
| Standard | | | | |
| | | | | |
+--------------+----------+----------+----------+----------+
| | | | | |
| | Notify | Publish | Notify | Notify |
| Experimental | (4) | (1) | (4) | (4) |
| Protocol | | | | |
| | | | | |
+--------------+----------+----------+----------+----------+
| | | | | |
| Information | Publish | Publish |Discretion|Discretion|
| or Opinion | (1) | (1) | (5) | (5) |
| Paper | | | | |
| | | | | |
+==========================================================+

(1) Publish.

(2) Bogus. Inform the source of the rules. RFCs specifying
Standard, or Draft Standard must come from the IESG, only.

(3) Refer to an Area Director for review by a WG. Expect to see
the document again only after approval by the IESG.

(4) Notify both the IESG and IRSG. If no concerns are raised in
two weeks then do Discretion (5), else RFC Editor to resolve
the concerns or do Refer (3).

(5) RFC Editor's discretion. The RFC Editor decides if a review
is needed and if so by whom. RFC Editor decides to publish or
not.





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Of course, in all cases the RFC Editor can request or make minor
changes for style, format, and presentation purposes.

The IESG has designated the IESG Secretary as its agent for
forwarding documents with IESG approval and for registering concerns
in response to notifications (4) to the RFC Editor. Documents from
Area Directors or Working Group Chairs may be considered in the same
way as documents from "other".

5.2. The Standards Track Diagram

There is a part of the STATUS and STATE categorization that is called
the standards track. Actually, only the changes of state are
significant to the progression along the standards track, though the
status assignments may change as well.

The states illustrated by single line boxes are temporary states,
those illustrated by double line boxes are long term states. A
protocol will normally be expected to remain in a temporary state for
several months (minimum six months for proposed standard, minimum
four months for draft standard). A protocol may be in a long term
state for many years.

A protocol may enter the standards track only on the recommendation
of the IESG; and may move from one state to another along the track
only on the recommendation of the IESG. That is, it takes action by
the IESG to either start a protocol on the track or to move it along.

Generally, as the protocol enters the standards track a decision is
made as to the eventual STATUS, requirement level or applicability
(elective, recommended, or required) the protocol will have, although
a somewhat less stringent current status may be assigned, and it then
is placed in the the proposed standard STATE with that status. So
the initial placement of a protocol is into state 1. At any time the
STATUS decision may be revisited.
















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