TLV Naming in the Mobile Ad Hoc Network (MANET) Generalized Packet/Message Format
A pure naming cleanup of the MANET TLV registries so type extensions can be allocated without misleading names.
Dearlove, C. and T. Clausen, "TLV Naming in the Mobile Ad Hoc Network (MANET) Generalized Packet/Message Format", RFC 7631, DOI 10.17487/RFC7631, September 2015, <https://www.rfc-editor.org/info/rfc7631>.
@misc{rfc7631,
series = {Request for Comments},
number = 7631,
howpublished = {RFC 7631},
publisher = {RFC Editor},
doi = {10.17487/RFC7631},
url = {https://www.rfc-editor.org/info/rfc7631},
author = {C. Dearlove and T. Clausen},
title = {{TLV Naming in the Mobile Ad Hoc Network (MANET) Generalized Packet/Message Format}},
pagetotal = 15,
year = 2015,
month = sep,
} RFC text
Contents
Internet Engineering Task Force (IETF) C. Dearlove
Request for Comments: 7631 BAE Systems ATC
Updates: 5444 T. Clausen
Category: Standards Track LIX, Ecole Polytechnique
ISSN: 2070-1721 September 2015
TLV Naming in the Mobile Ad Hoc Network (MANET)
Generalized Packet/Message Format
Abstract
This document reorganizes the naming of already-allocated TLV (type-
length-value) types and type extensions in the "Mobile Ad hoc NETwork
(MANET) Parameters" registries defined by RFC 5444 to use names
appropriately. It has no consequences in terms of any protocol
implementation.
This document also updates the Expert Review guidelines in RFC 5444,
so as to establish a policy for consistent naming of future TLV type
and type extension allocations. It makes no other changes to
RFC 5444.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7631.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................4
3. IANA Considerations .............................................4
3.1. Expert Review: Evaluation Guidelines .......................5
3.2. Updated IANA Registries ....................................6
4. Security Considerations ........................................13
5. References .....................................................13
5.1. Normative References ......................................13
5.2. Informative References ....................................14
Acknowledgments ...................................................15
Authors' Addresses ................................................15
1. Introduction
This document reorganizes and rationalizes the naming of TLVs (type-
length-value structures) defined by [RFC5444] and recorded by IANA in
the following subregistries of the "Mobile Ad hoc NETwork (MANET)
Parameters" registry: "Packet TLV Types", "Message TLV Types", and
"Address Block TLV Types".
This document reorganizes the naming of already-allocated Packet,
Message, and Address Block TLV types, and their corresponding type
extensions. It also updates the corresponding IANA registries.
TLVs have a type (one octet) and a type extension (one octet) that
together form a full type (of two octets). A TLV may omit the type
extension when it is zero. However, that applies only to its
representation; it still has a type extension of zero. A TLV type
defines an IANA registry of type extensions for that type.
There have been two forms of TLV allocation.
The first, but less common, form of allocation has been that
allocation of the TLV type has defined (but not necessarily
allocated) all the type extensions for that TLV type. This applies,
for example, to the Address Block TLV LINK_METRIC specified in
[RFC7181]. The LINK_METRIC type extensions are all available for
allocation for different definitions of link metric. It is
appropriate in this case to apply the name LINK_METRIC to the type,
and also to all the full types corresponding to that type, as has
been done. Type extensions can then be individually named or can be
simply referred to by their number.
The second, more common, form of allocation has been that allocation
of the TLV type has defined only type extension 0, and possibly type
extension 1, for that TLV type. An example is the Address Block TLV
LINK_STATUS defined in [RFC6130], where only type extension 0 is
allocated. It is not reasonable to assume that the remaining 255
type extensions will be allocated to forms of LINK_STATUS. (Other
forms of link status are already catered to by the introduction, in
[RFC7188], of a registry for values of the LINK_STATUS TLV.) Thus,
the name LINK_STATUS should be attached to the specific type
extension for that type, i.e., to the full type and not to the TLV
type when used with any other type extensions. This was, however,
not done as part of the initial registration of this TLV type.
Effectively, this leaves, for the LINK_STATUS TLV type, the type
extensions 1-255 either unavailable for allocation (if applying
strictly the interpretation that they must relate to a LINK_STATUS)
or counterintuitively named for their intended function.
The purpose of this document is to change how names of the second
form are applied and recorded in IANA registries, and to provide
guidelines and instructions for future TLV type allocations. This is
to facilitate the addition of new TLVs using type extensions other
than 0, but without them having inappropriate names attached. So,
for example, LINK_STATUS will become the name of the full type
(composed of the TLV type 3 and the TLV type extension 0) and will
cease being the name of the TLV type 3. This leaves the question of
how to name the type. As it is not clear what other TLVs might be
defined for other type extensions of the same type, the type is
currently left unnamed and specified only by number.
This document also updates the Expert Review guidelines from
[RFC5444], so as to establish a policy for consistent naming of
future TLV type and type extension allocations.
For clarity, all currently allocated TLVs in [RFC5497], [RFC6130],
[RFC6621], [RFC7181], and [RFC7182] are listed in the IANA
Considerations section of this document, each specifying the updates
or indicating no change when that is appropriate (such as the
LINK_METRIC TLV and both TLVs defined in [RFC6621]). The only
changes are of naming.
Note that nothing in this document changes the operation of any
protocol. This naming is already used, in effect, in [RFC6130] and
[RFC7181], currently the main users of allocated TLVs. For example,
the former indicates that all usage of LINK_STATUS refers to that TLV
with type extension 0.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
All references to elements such as "packet", "message", and "TLV" in
this document refer to those defined in [RFC5444].
3. IANA Considerations
This document updates the Expert Review evaluation guidelines for
allocations in [RFC5444] in the "Packet TLV Types", "Message TLV
Types", and "Address Block TLV Types" registries and updates the
already-made allocations to conform with these guidelines.
3.1. Expert Review: Evaluation Guidelines
For registration in the "Packet TLV Types", "Message TLV Types", and
"Address Block TLV Types" registries, the following guidelines apply,
in addition to those given in Section 6.1 in [RFC5444]:
o If the requested TLV type immediately defines (but not necessarily
allocates) all the corresponding type extensions for versions of
that type, then a common name SHOULD be assigned for the TLV type.
This case is unchanged by this specification. This currently
includes TLV types named ICV, TIMESTAMP, and LINK_METRIC; it also
includes the HELLO Message-Type-specific TLVs defined in
[RFC6621].
o Otherwise, if the requested TLV type does not immediately define
all the corresponding type extensions for versions of that type,
then a common name SHOULD NOT be assigned for that TLV type.
Instead, it is RECOMMENDED that:
* The "description" for the allocated TLV type be "Defined by
Type Extension".
* For Packet TLV Types, the type extension registry, created for
the TLV type, be named "Type XX Packet TLV Type Extensions",
with XX replaced by the numerical value of the TLV type.
* For Message TLV Types, the type extension registry, created for
the TLV type, be named "Type XX Message TLV Type Extensions",
with XX replaced by the numerical value of the TLV type.
* For Address Block TLV Types, the type extension registry,
created for the TLV type, be named "Type XX Address Block TLV
Type Extensions", with XX replaced by the numerical value of
the TLV type.
* When a new type extension is required, unless there are reasons
to the contrary, the next consecutive type extension is
allocated and given a name. (Reasons to the contrary MAY
include maintaining a correspondence between corresponding
Packet, Message, and Address Block TLVs, and reserving type
extension zero if not yet allocated.)
3.2. Updated IANA Registries
The following changes (including correction of some existing minor
errors) apply to the IANA registry "Mobile Ad hoc NETwork (MANET)
Parameters". For clarity, registries that are unchanged, including
those that define all type extensions of a TLV type, are listed as
unchanged.
The IANA registry "Packet TLV Types" is unchanged.
The IANA registry "ICV Packet TLV Type Extensions" is unchanged.
The IANA registry "TIMESTAMP Packet TLV Type Extensions" is
unchanged.
The IANA registry "Message TLV Types" is changed to match Table 1.
+---------+-------------------------------+-----------+
| Type | Description | Reference |
+---------+-------------------------------+-----------+
| 0 | Defined by Type Extension | [RFC5497] |
| 1 | Defined by Type Extension | [RFC5497] |
| 2-4 | Unassigned | |
| 5 | ICV | [RFC7182] |
| 6 | TIMESTAMP | [RFC7182] |
| 7 | Defined by Type Extension | [RFC7181] |
| 8 | Defined by Type Extension | [RFC7181] |
| 9-223 | Unassigned | |
| 224-255 | Reserved for Experimental Use | [RFC5444] |
+---------+-------------------------------+-----------+
Table 1: Message TLV Types
The IANA registry "INTERVAL_TIME Message Type Extensions" has been
renamed "Type 0 Message TLV Type Extensions" and changed to match
Table 2.
+-----------+---------------+---------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------------+---------------------------+-----------+
| 0 | INTERVAL_TIME | The maximum time before | [RFC5497] |
| | | another message of the | |
| | | same type as this message | |
| | | from the same originator | |
| | | should be received | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC5497] |
| | | Use | |
+-----------+---------------+---------------------------+-----------+
Table 2: Type 0 Message TLV Type Extensions
The IANA registry "VALIDITY_TIME Message Type Extensions" has been
renamed "Type 1 Message TLV Type Extensions" and changed to match
Table 3.
+-----------+---------------+---------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------------+---------------------------+-----------+
| 0 | VALIDITY_TIME | The time from receipt of | [RFC5497] |
| | | the message during which | |
| | | the information contained | |
| | | in the message is to be | |
| | | considered valid | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC5497] |
| | | Use | |
+-----------+---------------+---------------------------+-----------+
Table 3: Type 1 Message TLV Type Extensions
The IANA registry "ICV Message TLV Type Extensions" is unchanged.
The IANA registry "TIMESTAMP Message TLV Type Extensions" is
unchanged.
The IANA registry "MPR_WILLING Message Type Extensions" has been
renamed "Type 7 Message TLV Type Extensions" and changed to match
Table 4.
+-----------+-------------+-----------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+-------------+-----------------------------+-----------+
| 0 | MPR_WILLING | Bits 0-3 specify the | [RFC7181] |
| | | originating router's | |
| | | willingness to act as a | |
| | | flooding MPR; bits 4-7 | |
| | | specify the originating | |
| | | router's willingness to act | |
| | | as a routing MPR | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC7181] |
| | | Use | |
+-----------+-------------+-----------------------------+-----------+
Table 4: Type 7 Message TLV Type Extensions
The IANA registry "CONT_SEQ_NUM Message Type Extensions" has been
renamed "Type 8 Message TLV Type Extensions" and changed to match
Table 5.
+-----------+--------------+----------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+--------------+----------------------------+-----------+
| 0 | CONT_SEQ_NUM | Specifies a content | [RFC7181] |
| | (COMPLETE) | sequence number for this | |
| | | complete message | |
| 1 | CONT_SEQ_NUM | Specifies a content | [RFC7181] |
| | (INCOMPLETE) | sequence number for this | |
| | | incomplete message | |
| 2-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC7181] |
| | | Use | |
+-----------+--------------+----------------------------+-----------+
Table 5: Type 8 Message TLV Type Extensions
The IANA registry "HELLO Message-Type-specific Message TLV Types" is
unchanged.
The IANA registry "SMF_TYPE Message TLV Type Extensions" is
unchanged.
The IANA registry "TC Message-Type-specific Message TLV Types" is
unchanged.
The IANA registry "Address Block TLV Types" has been changed to match
Table 6.
+---------+-------------------------------+-----------+
| Type | Description | Reference |
+---------+-------------------------------+-----------+
| 0 | Defined by Type Extension | [RFC5497] |
| 1 | Defined by Type Extension | [RFC5497] |
| 2 | Defined by Type Extension | [RFC6130] |
| 3 | Defined by Type Extension | [RFC6130] |
| 4 | Defined by Type Extension | [RFC6130] |
| 5 | ICV | [RFC7182] |
| 6 | TIMESTAMP | [RFC7182] |
| 7 | LINK_METRIC | [RFC7181] |
| 8 | Defined by Type Extension | [RFC7181] |
| 9 | Defined by Type Extension | [RFC7181] |
| 10 | Defined by Type Extension | [RFC7181] |
| 11-223 | Unassigned | |
| 224-255 | Reserved for Experimental Use | [RFC5444] |
+---------+-------------------------------+-----------+
Table 6: Address Block TLV Types
The IANA registry "INTERVAL_TIME Address Block TLV Type Extensions"
has been renamed "Type 0 Address Block TLV Type Extensions" and
changed to match Table 7.
+-----------+---------------+---------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------------+---------------------------+-----------+
| 0 | INTERVAL_TIME | The maximum time before | [RFC5497] |
| | | another message of the | |
| | | same type as this message | |
| | | from the same originator | |
| | | and containing this | |
| | | address should be | |
| | | received | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC5497] |
| | | Use | |
+-----------+---------------+---------------------------+-----------+
Table 7: Type 0 Address Block TLV Type Extensions
The IANA registry "VALIDITY_TIME Address Block TLV Type Extensions"
has been renamed "Type 1 Address Block TLV Type Extensions" and
changed to match Table 8.
+-----------+---------------+---------------------------+-----------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------------+---------------------------+-----------+
| 0 | VALIDITY_TIME | The time from receipt of | [RFC5497] |
| | | the address during which | |
| | | the information regarding | |
| | | this address is to be | |
| | | considered valid | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | [RFC5497] |
| | | Use | |
+-----------+---------------+---------------------------+-----------+
Table 8: Type 1 Address Block TLV Type Extensions
The IANA registry "LOCAL_IF Address Block TLV Type Extensions" has
been renamed "Type 2 Address Block TLV Type Extensions" and changed
to match Table 9.
+-----------+----------+-----------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+----------+-----------------------+--------------------+
| 0 | LOCAL_IF | This value is to be | [RFC7188][RFC6130] |
| | | interpreted according | |
| | | to the registry | |
| | | "LOCAL_IF TLV Values" | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for | [RFC6130] |
| | | Experimental Use | |
+-----------+----------+-----------------------+--------------------+
Table 9: Type 2 Address Block TLV Type Extensions
The IANA registry "LINK_STATUS Address Block TLV Type Extensions" has
been renamed "Type 3 Address Block TLV Type Extensions" and changed
to match Table 10.
+-----------+-------------+--------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+-------------+--------------------+--------------------+
| 0 | LINK_STATUS | This value is to | [RFC7188][RFC6130] |
| | | be interpreted | |
| | | according to the | |
| | | registry | |
| | | "LINK_STATUS TLV | |
| | | Values" | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for | [RFC6130] |
| | | Experimental Use | |
+-----------+-------------+--------------------+--------------------+
Table 10: Type 3 Address Block TLV Type Extensions
The IANA registry "OTHER_NEIGHB Address Block TLV Type Extensions"
has been renamed "Type 4 Address Block TLV Type Extensions" and
changed to match Table 11.
+-----------+--------------+-------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+--------------+-------------------+--------------------+
| 0 | OTHER_NEIGHB | This value is to | [RFC7188][RFC6130] |
| | | be interpreted | |
| | | according to the | |
| | | registry | |
| | | "OTHER_NEIGHB TLV | |
| | | Values" | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for | [RFC6130] |
| | | Experimental Use | |
+-----------+--------------+-------------------+--------------------+
Table 11: Type 4 Address Block TLV Type Extensions
The IANA registry "ICV Address TLV Type Extensions" has been renamed
"ICV Address Block TLV Type Extensions" but is otherwise unchanged.
The IANA registry "TIMESTAMP Address TLV Type Extensions" has been
renamed "TIMESTAMP Address Block TLV Type Extensions" but is
otherwise unchanged.
The IANA registry "LINK_METRIC Address Block TLV Type Extensions" is
unchanged.
The IANA registry "MPR Address Block TLV Type Extensions" has been
renamed "Type 8 Address Block TLV Type Extensions" and changed to
match Table 12.
+-----------+------+---------------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+------+---------------------------+--------------------+
| 0 | MPR | This value is to be | [RFC7188][RFC7181] |
| | | interpreted according to | |
| | | the registry "MPR TLV Bit | |
| | | Values" | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for Experimental | RFC 7631 (this |
| | | Use | document) |
+-----------+------+---------------------------+--------------------+
Table 12: Type 8 Address Block TLV Type Extensions
The IANA registry "NBR_ADDR_TYPE Address Block TLV Type Extensions"
has been renamed "Type 9 Address Block TLV Type Extensions" and
changed to match Table 13.
+-----------+---------------+------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------------+------------------+--------------------+
| 0 | NBR_ADDR_TYPE | This value is to | [RFC7188][RFC7181] |
| | | be interpreted | |
| | | according to the | |
| | | registry | |
| | | "NBR_ADDR_TYPE | |
| | | Address Block | |
| | | TLV Bit Values" | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for | RFC 7631 (this |
| | | Experimental Use | document) |
+-----------+---------------+------------------+--------------------+
Table 13: Type 9 Address Block TLV Type Extensions
The IANA registry "GATEWAY Address Block TLV Type Extensions" has
been renamed "Type 10 Address Block TLV Type Extensions" and changed
to match Table 14.
+-----------+---------+------------------------+--------------------+
| Type | Name | Description | Reference |
| Extension | | | |
+-----------+---------+------------------------+--------------------+
| 0 | GATEWAY | Specifies that a given | [RFC7188][RFC7181] |
| | | network address is | |
| | | reached via a gateway | |
| | | on the originating | |
| | | router, with value | |
| | | equal to the number of | |
| | | hops | |
| 1-223 | | Unassigned | |
| 224-255 | | Reserved for | RFC 7631 (this |
| | | Experimental Use | document) |
+-----------+---------+------------------------+--------------------+
Table 14: Type 10 Address Block TLV Type Extensions
The IANA registry "HELLO Message-Type-specific Address Block TLV
Types" is unchanged.
The IANA registry "SMF_NBR_TYPE Address Block TLV Type Extensions" is
unchanged.
The IANA registry "TC Message-Type-specific Address Block TLV Types"
is unchanged.
Note: This document adds reservations for Experimental Use [RFC5226],
omitted in [RFC7181], to the last three tables.
4. Security Considerations
As this document is concerned only with how entities are named, those
names being used only in documents such as this and IANA registries,
this document has no security considerations.
5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized Mobile Ad Hoc Network (MANET) Packet/Message
Format", RFC 5444, DOI 10.17487/RFC5444, February 2009,
<http://www.rfc-editor.org/info/rfc5444>.
[RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value
Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497,
DOI 10.17487/RFC5497, March 2009,
<http://www.rfc-editor.org/info/rfc5497>.
[RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, DOI 10.17487/RFC6130, April 2011,
<http://www.rfc-editor.org/info/rfc6130>.
[RFC6621] Macker, J., Ed., "Simplified Multicast Forwarding",
RFC 6621, DOI 10.17487/RFC6621, May 2012,
<http://www.rfc-editor.org/info/rfc6621>.
[RFC7181] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
"The Optimized Link State Routing Protocol Version 2",
RFC 7181, DOI 10.17487/RFC7181, April 2014,
<http://www.rfc-editor.org/info/rfc7181>.
[RFC7182] Herberg, U., Clausen, T., and C. Dearlove, "Integrity
Check Value and Timestamp TLV Definitions for Mobile Ad
Hoc Networks (MANETs)", RFC 7182, DOI 10.17487/RFC7182,
April 2014, <http://www.rfc-editor.org/info/rfc7182>.
[RFC7188] Dearlove, C. and T. Clausen, "Optimized Link State Routing
Protocol Version 2 (OLSRv2) and MANET Neighborhood
Discovery Protocol (NHDP) Extension TLVs", RFC 7188,
DOI 10.17487/RFC7188, April 2014,
<http://www.rfc-editor.org/info/rfc7188>.
5.2. Informative References
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
Acknowledgments
The authors would like to thank Adrian Farrel for pointing out the
need to reorganize and rationalize the naming of the TLVs defined by
[RFC5444] and Tom Taylor and the RFC Editor for pointing out some
omissions and errors.
Authors' Addresses
Christopher Dearlove
BAE Systems Advanced Technology Centre
West Hanningfield Road
Great Baddow, Chelmsford
United Kingdom
Phone: +44 1245 242194
Email: chris.dearlove@baesystems.com
URI: http://www.baesystems.com/
Thomas Heide Clausen
LIX, Ecole Polytechnique
Phone: +33 6 6058 9349
Email: T.Clausen@computer.org
URI: http://www.ThomasClausen.org/
ISO Plain Language
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§1A Naming Cleanup, Not a Protocol Change
This document reorganizes and rationalizes the naming of TLVs, meaning type-length-value structures, defined by RFC 5444 and recorded by IANA in three subregistries of the "Mobile Ad hoc NETwork (MANET) Parameters" registry: "Packet TLV Types", "Message TLV Types" and "Address Block TLV Types". The only changes are of naming. Nothing in the document changes the operation of any protocol.
The reason is that TLVs are allocated in two different ways, and only one of them suits a name. The first, less common, form is where the allocation of the TLV type has defined, but not necessarily allocated, all the type extensions for that TLV type. The Address Block TLV LINK_METRIC specified in RFC 7181 is an example: all of its type extensions are available for allocation for different definitions of link metric, so it is appropriate to apply the name LINK_METRIC to the type and to all the full types that correspond to it. Type extensions can then be named individually or simply referred to by their number.
The second, more common, form is where the allocation of the TLV type has defined only type extension 0, and possibly type extension 1. The Address Block TLV LINK_STATUS defined in RFC 6130 is an example, where only type extension 0 is allocated. It is not reasonable to assume that the remaining 255 type extensions will be allocated to forms of LINK_STATUS, and other forms of link status are already catered to by the registry for values of the LINK_STATUS TLV introduced in RFC 7188. The name LINK_STATUS should therefore be attached to the specific type extension, that is, to the full type, and not to the TLV type when used with any other type extensions. That was not done when the TLV type was first registered. The effect is that the type extensions 1 to 255 are left either unavailable for allocation, under a strict reading, or counterintuitively named for whatever function they end up serving.
The purpose of the document is to change how names of the second form are applied and recorded in the IANA registries, and to give guidelines for future allocations. LINK_STATUS becomes the name of the full type made up of TLV type 3 and TLV type extension 0, and ceases to be the name of TLV type 3. The type itself is left unnamed and specified only by number, because it is not clear what other TLVs might be defined for its other type extensions. The RFC notes that this naming is already used, in effect, in RFC 6130 and RFC 7181, the main users of allocated TLVs: RFC 6130 indicates that all usage of LINK_STATUS refers to that TLV with type extension 0.
Some TLV names were given to a whole family of numbers when only one of them was ever defined. That left the rest of the family unusable, or waiting to be named after whatever they ended up carrying. This document attaches each name to the exact number it describes, and leaves the family name free for whatever comes next.
- Type defines all extensionsA common name is given to the type and to every full type under it. LINK_METRIC is the example.
- Type defines one extensionThe name belongs to the full type only, and the type itself is described as Defined by Type Extension.
- Extension registriesEach type gets a registry named Type XX ... TLV Type Extensions, with XX the type number.
- No behaviour changeOnly names change. Protocols behave exactly as they did before.
§2Types and Type Extensions
Section 2 of the RFC sets out the conventions. The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY and OPTIONAL are to be interpreted as described in RFC 2119. All references to elements such as "packet", "message" and "TLV" refer to those defined in RFC 5444.
The structural point is short. A TLV has a type, of one octet, and a type extension, of one octet, and the two together form a full type of two octets. A TLV may omit the type extension when it is zero, but that applies only to its representation on the wire: it still has a type extension of zero. A TLV type defines an IANA registry of type extensions for that type, so every type owns a list of extensions, and it is the extension that names the particular meaning.
Each kind of information in a MANET packet is identified by two numbers, one for the kind and one for the version of that kind. Together they make a full type, and the version number is what this document is about.
§3.1The Rules for Naming Future Allocations
Section 3.1 replaces the Expert Review evaluation guidelines of RFC 5444 for the "Packet TLV Types", "Message TLV Types" and "Address Block TLV Types" registries, adding to the guidelines already given in Section 6.1 of that RFC.
The first rule keeps the existing case. If the requested TLV type immediately defines, but not necessarily allocates, all the corresponding type extensions for versions of that type, then a common name SHOULD be assigned for the TLV type. This case is unchanged by the document, and currently covers the TLV types named ICV, TIMESTAMP and LINK_METRIC, as well as the HELLO Message-Type-specific TLVs defined in RFC 6621.
The second rule is new. If the requested TLV type does not immediately define all the corresponding type extensions, then a common name SHOULD NOT be assigned for that TLV type. Instead it is RECOMMENDED that the "description" for the allocated TLV type be "Defined by Type Extension", and that the type extension registry created for the TLV type be named "Type XX Packet TLV Type Extensions", "Type XX Message TLV Type Extensions" or "Type XX Address Block TLV Type Extensions", with XX replaced by the numerical value of the TLV type.
The third recommendation covers how extensions themselves are named. When a new type extension is required, and unless there are reasons to the contrary, the next consecutive type extension is allocated and given a name. The RFC allows reasons to the contrary, which may include maintaining a correspondence between corresponding Packet, Message and Address Block TLVs, and reserving type extension zero if it is not yet allocated.
The rule for new entries is simple: if a whole family of versions is defined at once, give the family a name. If only one or two versions exist, leave the family unnamed, describe it as defined by its extension, and give each version its own name.
§3.2The Renamed Registries
Section 3.2 lists every change to the MANET Parameters registry, including corrections of some existing minor errors, and lists unchanged registries for clarity. The "Packet TLV Types" registry is unchanged, as are the "ICV Packet TLV Type Extensions" and "TIMESTAMP Packet TLV Type Extensions" registries.
The "Message TLV Types" registry changes to match Table 1. Types 0 and 1 become "Defined by Type Extension" against RFC 5497, types 2 to 4 are unassigned, type 5 is ICV and type 6 is TIMESTAMP against RFC 7182, types 7 and 8 become "Defined by Type Extension" against RFC 7181, types 9 to 223 are unassigned, and types 224 to 255 are reserved for experimental use. The registries underneath them are renamed to match: "INTERVAL_TIME Message Type Extensions" becomes "Type 0 Message TLV Type Extensions", "VALIDITY_TIME Message Type Extensions" becomes "Type 1 Message TLV Type Extensions", "MPR_WILLING Message Type Extensions" becomes "Type 7 Message TLV Type Extensions", and "CONT_SEQ_NUM Message Type Extensions" becomes "Type 8 Message TLV Type Extensions". The "ICV" and "TIMESTAMP" message registries are unchanged, as are the HELLO, SMF_TYPE and TC message-specific ones.
The "Address Block TLV Types" registry changes to match Table 6. Types 0 and 1 become "Defined by Type Extension" against RFC 5497, types 2, 3 and 4 become "Defined by Type Extension" against RFC 6130, type 5 is ICV and type 6 is TIMESTAMP against RFC 7182, type 7 is LINK_METRIC against RFC 7181, types 8, 9 and 10 become "Defined by Type Extension" against the same RFC, types 11 to 223 are unassigned, and types 224 to 255 are reserved for experimental use. The registries underneath are renamed in the same way: "INTERVAL_TIME", "VALIDITY_TIME", "LOCAL_IF", "LINK_STATUS" and "OTHER_NEIGHB" become the Type 0, Type 1, Type 2, Type 3 and Type 4 Address Block TLV Type Extensions registries, while "MPR", "NBR_ADDR_TYPE" and "GATEWAY" become the Type 8, Type 9 and Type 10 ones. Two registries are renamed without any other change: "ICV Address TLV Type Extensions" becomes "ICV Address Block TLV Type Extensions", and "TIMESTAMP Address TLV Type Extensions" becomes "TIMESTAMP Address Block TLV Type Extensions". The "LINK_METRIC Address Block TLV Type Extensions" registry, which defines all the extensions of its type, is unchanged, as are the HELLO, SMF_NBR_TYPE and TC address block registries. One further change: the document adds reservations for experimental use, following RFC 5226, which RFC 7181 had omitted, to the last three tables.
The registry entries themselves are rewritten. Most type numbers now say only "Defined by Type Extension", and the lists underneath them are renamed after the number of the type they belong to, such as "Type 3 Address Block TLV Type Extensions".
| Type | Description | Reference |
|---|---|---|
| 0 | Defined by Type Extension | RFC 5497 |
| 1 | Defined by Type Extension | RFC 5497 |
| 2-4 | Unassigned | |
| 5 | ICV | RFC 7182 |
| 6 | TIMESTAMP | RFC 7182 |
| 7 | Defined by Type Extension | RFC 7181 |
| 8 | Defined by Type Extension | RFC 7181 |
| 9-223 | Unassigned | |
| 224-255 | Reserved for Experimental Use | RFC 5444 |
- Message 0Type 0 Message TLV Type Extensions — Was INTERVAL_TIME Message Type Extensions.
- Message 1Type 1 Message TLV Type Extensions — Was VALIDITY_TIME Message Type Extensions.
- Message 7Type 7 Message TLV Type Extensions — Was MPR_WILLING Message Type Extensions.
- Message 8Type 8 Message TLV Type Extensions — Was CONT_SEQ_NUM Message Type Extensions.
- Address 2Type 2 Address Block TLV Type Extensions — Was LOCAL_IF Address Block TLV Type Extensions.
- Address 3Type 3 Address Block TLV Type Extensions — Was LINK_STATUS Address Block TLV Type Extensions.
- Address 4Type 4 Address Block TLV Type Extensions — Was OTHER_NEIGHB Address Block TLV Type Extensions.
- Address 8Type 8 Address Block TLV Type Extensions — Was MPR Address Block TLV Type Extensions.
- Address 9Type 9 Address Block TLV Type Extensions — Was NBR_ADDR_TYPE Address Block TLV Type Extensions.
- Address 10Type 10 Address Block TLV Type Extensions — Was GATEWAY Address Block TLV Type Extensions.
§4Security Considerations
The RFC has one paragraph here. As the document is concerned only with how entities are named, and those names are used only in documents such as this one and in IANA registries, it has no security considerations.
Nothing here can affect the security of a network, because the document only changes labels in a registry.