Network Working Group F. Templin, Ed.
Internet-Draft The Boeing Company
Intended status: Standards Track A. Whyman
Expires: April 15, 2021 MWA Ltd c/o Inmarsat Global Ltd
October 12, 2020
IPv6 Neighbor Discovery Overlay Multilink Network Interface (OMNI)
Option
draft-templin-6man-omni-option-01
Abstract
This document defines a new IPv6 Neighbor Discovery (ND) option
termed the "Overlay Multilink Network Interface (OMNI) Option". The
OMNI option may appear in any IPv6 ND message type; it is processed
by interface types that recognize the option and ignored by all other
interface types. The option supports functions such as prefix
registration and multilink coordination, and is extensible to support
additional functions in the future.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. The Overlay Multilink Network Interface (OMNI) IPv6 ND Option 3
3.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.3. Interface Attributes (Type 1) . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
This document defines a new IPv6 Neighbor Discovery (ND) option
termed the "Overlay Multilink Network Interface (OMNI) Option". The
OMNI option may appear in any IPv6 ND message type; it is processed
by interface types that recognize the option and ignored by all other
interface types. The option supports functions such as prefix
registration and multilink coordination for interface types such as
the OMNI interface [I-D.templin-6man-omni-interface], and is
extensible to support additional functions in the future.
The following sections discuss the OMNI option format and contents.
Uses for the option are specified in IPv6 over specific link layer
documents such as [I-D.templin-6man-omni-interface]. An IPv6 ND
option Type number assignment is requested in the IANA Considerations
section.
2. Terminology
The terminology in the normative references applies. The term
"underlying interface" refers to one of potentially multiple Layer-2
interfaces over which a Layer-3 (virtual) interface is configured.
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 BCP
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14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. The Overlay Multilink Network Interface (OMNI) IPv6 ND Option
An Overlay Multilink Network Interface (OMNI) IPv6 ND option is
defined. The option (known as the "OMNI option") is formatted as
shown in Figure 1:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length | S/T-omIndex |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Sub-Options ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: OMNI Option Format
In this format:
o Type is set to TBD.
o Length is set to the number of 8 octet blocks in the option.
o Prefix Length is a 1-octet field that encodes a value between 0
and 128 as a prefix length for the IPv6 source or destination
address of the IPv6 ND message. Prefix Length is set to the
length of the prefix for addresses that include a global or
unique-local prefix; for other address types, it is set to the
value 128.
o S/T-omIndex is a 1-octet field that encodes a value between 0 and
255 identifying the source or target underlying interface for the
IPv6 ND message. For RS and NS messages S/T-omIndex refers to the
"Source" underlying interface over which the message is sent,
while for RA and NA messages S/T-omIndex refers to the "Target"
underlying interface that will receive the message.
o Sub-Options is a Variable-length field, of length such that the
complete OMNI Option is an integer multiple of 8 octets long.
Contains one or more Sub-Options, as described in Section 3.1.
The OMNI option may appear in any IPv6 ND message type; it is
processed by interfaces that recognize the option and ignored by all
other interfaces. If a single IPv6 ND message contains multiple OMNI
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options, the first option is processed and any additional options are
ignored.
An OMNI option may include full or partial information for the
neighbor. If an OMNI option with full information is received, its
contents provide new information and/or update any previously cached
information. If an OMNI option with partial information is received,
it contents provide new information and/or update only the
corresponding previously cached information. The union of the
information in the most recently received OMNI options is therefore
retained, and the information is aged/removed in conjunction with the
corresponding neighbor cache entry.
3.1. Sub-Options
The OMNI option includes zero or more Sub-Options. Each consecutive
Sub-Option is concatenated immediately after its predecessor. All
Sub-Options except Pad1 (see below) are in type-length-value (TLV)
encoded in the following format:
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Sub-Type | Sub-length | Sub-Option Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 2: Sub-Option Format
o Sub-Type is a 1-octet field that encodes the Sub-Option type.
Sub-Options defined in this document are:
Option Name Sub-Type
Pad1 0
PadN 1
Interface Attributes (Type 1) 2
Figure 3
Sub-Types 253 and 254 are reserved for experimentation; Sub-Type
255 is reserved by IANA.
o Sub-Length is a 1-octet field that encodes the length of the Sub-
Option Data (i.e., ranging from 0 to 255 octets).
o Sub-Option Data is a block of data with format determined by Sub-
Type.
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During processing, unrecognized Sub-Options are ignored and the next
Sub-Option processed until the end of the OMNI option is reached.
The following Sub-Option types and formats are defined in this
document (note that other documents that are active at the time of
this writing will define additional Sub-Option types in the near
future):
3.1.1. Pad1
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| Sub-Type=0 |
+-+-+-+-+-+-+-+-+
Figure 4: Pad1
o Sub-Type is set to 0. If multiple instances appear in the same
OMNI option all are processed.
o No Sub-Length or Sub-Option Data follows (i.e., the "Sub-Option"
consists of a single zero octet).
3.1.2. PadN
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Sub-Type=1 | Sub-length=N | N padding octets ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 5: PadN
o Sub-Type is set to 1. If multiple instances appear in the same
OMNI option all are processed.
o Sub-Length is set to N (from 0 to 255) being the number of padding
octets that follow.
o Sub-Option Data consists of N padding octets that are typically
zero-valued (any non-zero values that may appear in the padding
octets are not to be interpreted in any way other than as simple
padding).
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3.1.3. Interface Attributes (Type 1)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type=2 | Sub-length=N | omIndex | omType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Provider ID | Link | Resvd |P00|P01|P02|P03|P04|P05|P06|P07|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P24|P25|P26|P27|P28|P29|P30|P31|P32|P33|P34|P35|P36|P37|P38|P39|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P40|P41|P42|P43|P44|P45|P46|P47|P48|P49|P50|P51|P52|P53|P54|P55|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P56|P57|P58|P59|P60|P61|P62|P63|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Interface Attributes (Type 1)
o Sub-Type is set to 2. If multiple instances with different
omIndex values appear in the same OMNI option all are processed;
if multiple instances with the same omIndex value appear, the
first is processed and all others are ignored
o Sub-Length is set to N (from 1 to 255) that encodes the number of
Sub-Option Data octets that follow.
o omIndex is a 1-octet field containing a value from 0 to 255
identifying the underlying interface for which the interface
attributes apply.
o omType is a 1-octet field containing a value from 0 to 255
corresponding to the underlying interface identified by omIndex.
o Provider ID is a 1-octet field containing a value from 0 to 255
corresponding to the underlying interface identified by omIndex.
o Link encodes a 4-bit link metric. The value '0' means the link is
DOWN, and the remaining values mean the link is UP with metric
ranging from '1' ("lowest") to '15' ("highest").
o Resvd is reserved for future use.
o A 16-octet ""Preferences" field immediately follows 'Resvd', with
values P[00] through P[63] corresponding to the 64 Differentiated
Service Code Point (DSCP) values [RFC2474]. Each 2-bit P[*] field
is set to the value '0' ("disabled"), '1' ("low"), '2' ("medium")
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or '3' ("high") to indicate a QoS preference for underlying
interface selection purposes.
4. IANA Considerations
The IANA is instructed to allocate a Type number TBD from the
registry "IPv6 Neighbor Discovery Option Formats" for the OMNI option
(see: Section 13 of [RFC4861]) as a provisional registration in
accordance with Section 4.13 of [RFC8126].
The OMNI option also defines an 8-bit Sub-Type field, for which IANA
is instructed to create and maintain a new registry entitled "OMNI
option Sub-Type values". Initial values for the OMNI option Sub-Type
values registry are given below; future assignments are to be made
through Expert Review [RFC8126].
Value Sub-Type name Reference
----- ------------- ----------
0 Pad1 [RFCXXXX]
1 PadN [RFCXXXX]
2 Interface Attributes (Type 1) [RFCXXXX]
3-252 Unassigned
253-254 Experimental [RFCXXXX]
255 Reserved [RFCXXXX]
Figure 7: OMNI Option Sub-Type Values
5. Security Considerations
Security considerations for IPv6 [RFC8200] and IPv6 Neighbor
Discovery [RFC4861] apply.
6. Acknowledgements
This document is aligned with the IETF 6man (IPv6) working group.
7. References
7.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
7.2. Informative References
[I-D.templin-6man-omni-interface]
Templin, F. and T. Whyman, "Transmission of IP Packets
over Overlay Multilink Network (OMNI) Interfaces", draft-
templin-6man-omni-interface-47 (work in progress), October
2020.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>.
Authors' Addresses
Fred L. Templin (editor)
The Boeing Company
P.O. Box 3707
Seattle, WA 98124
USA
Email: fltemplin@acm.org
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Tony Whyman
MWA Ltd c/o Inmarsat Global Ltd
99 City Road
London EC1Y 1AX
England
Email: tony.whyman@mccallumwhyman.com
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