Transmission of IPv6 Packets over AERO Interfaces
draft-templin-atn-aero-interface-00
The information below is for an old version of the document.
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| Authors | Fred Templin , Tony Whyman | ||
| Last updated | 2019-03-29 | ||
| Replaced by | draft-templin-6man-omni-interface, draft-templin-6man-omni-interface | ||
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draft-templin-atn-aero-interface-00
Network Working Group F. Templin, Ed.
Internet-Draft Boeing Research & Technology
Intended status: Standards Track A. Whyman
Expires: September 30, 2019 MWA Ltd c/o Inmarsat Global Ltd
March 29, 2019
Transmission of IPv6 Packets over AERO Interfaces
draft-templin-atn-aero-interface-00.txt
Abstract
Mobile nodes (e.g., aircraft of various configurations) act as mobile
routers for their on-board networks, and may have multiple data links
for communicating with networked correspondents. Mobile nodes
configure a virtual interface (termed the "AERO interface") as a thin
layer over their underlying data link interfaces. This document
specifies the transmission of IPv6 packets over AERO interfaces.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 30, 2019.
Copyright Notice
Copyright (c) 2019 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
(https://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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
4. AERO Interface Model . . . . . . . . . . . . . . . . . . . . 4
5. Maximum Transmission Unit . . . . . . . . . . . . . . . . . . 4
6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Link-Local Addresses . . . . . . . . . . . . . . . . . . . . 6
8. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 7
9. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 10
10. Router Discovery and MNP Assertion . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 11
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
14.1. Normative References . . . . . . . . . . . . . . . . . . 12
14.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. S/TLLAO Extensions for Special-Purpose Links . . . . 13
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Mobile Nodes (MNs) such as aircraft of various configurations may
have multiple data links for communicating with networked
correspondents. These data links often have differing performance,
cost and availability characteristics that can change dynamically
according to mobility patterns, flight phases, proximity to
infrastructure, etc.
Each MN receives an IPv6 Mobile Network Prefix (MNP) that can be used
by on-board networks regardless of the actual link or links selected
for data transport. The MN acts as a mobile router on behalf of its
on-board networks, but appears as a multi-addressed host from the
perspective of off-board correspondents. This implies the need for a
virtual interface (termed the "AERO interface") configured as a thin
layer over the underlying data link interfaces.
The AERO interface is therefore the only interface abstraction
exposed to the IPv6 layer, and behaves according to the Non-
Broadcast, Multiple Access (NBMA) interface principle. This document
specifies the transmission of IPv6 packets [RFC8200] over AERO
interfaces.
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2. Terminology
The terminology in the normative references applies; especially, the
terms "link" and "interface" are the same as defined in the IPv6
[RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications.
The following terms are defined within the scope of this document:
underlying Internetwork
a connected network region that has a coherent IP addressing plan
and is either physically isolated or separated from other networks
by packet filtering border routers. Examples include private
enterprise networks, aviation networks and the global public
Internet itself.
AERO link
a Non-Broadcast, Multiple Access (NBMA) virtual overlay configured
over an underlying Internetwork. Nodes on the AERO link appear as
single-hop neighbors from the perspective of the virtual overlay
even though they may be separated by many underlying Internetwork
hops. An AERO link may comprise multiple segments joined by
bridges the same as for any link; the underlying Internetwork
addressing plans in each segment may be mutually exclusive and
managed by different administrative entities.
AERO interface
a node's attachment to an AERO link, and configured over one or
more underlying interfaces
AERO node
a node with an AERO interface attached to an AERO link.
AERO address
an IPv6 link-local address constructed as specified in Section 7.
underlying link
a link that connects an AERO node to the underlying Internetwork.
underlying interface
an AERO node's interface point of attachment to an underlying
link.
3. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. Lower case
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uses of these words are not to be interpreted as carrying RFC2119
significance.
4. AERO Interface Model
An AERO interface is a MN's virtual interface configured over one or
more underlying links, which may be physical (e.g., an Ethernet) or
virtual (e.g., an Internet or higher-layer "tunnel"). The MN
discovers routers on the AERO link through Router Solicitation (RS) /
Router Advertisement (RA) message exchanges.
The AERO interface architectural layering model is the same as in
[RFC7847], and reproduced here (in an augmented form) as shown in
Figure 1. The AERO interface is therefore a single network-layer
interface with multiple link-layer addresses.
+----------------------------+
| TCP/UDP |
Session-to-IP +---->| |
Address Binding | +----------------------------+
+---->| IPv6 |
IP Address +---->| |
Binding | +----------------------------+
+---->| AERO Interface |
Logical-to- +---->| (AERO Address) |
Physical | +----------------------------+
Interface +---->| L2 | L2 | | L2 |
Binding |(IF#1)|(IF#2)| ..... |(IF#n)|
+------+------+ +------+
| L1 | L1 | | L1 |
| | | | |
+------+------+ +------+
Figure 1: AERO Interface Architectural Layering Model
5. Maximum Transmission Unit
The AERO interface Maximum Transmission Unit (MTU) is derived from
the underlying interface MTUs and set to a value that ensures that
the MTU for each underlying interface is respected. The AERO
interface MTU may be common to all data flows or differ between data
flows. Regardless of the strategy by which the MTU is determined,
the AERO link administrative authority should configure routers to
advertise a conservative MTU for all nodes noting that fragmentation
should be avoided if possible.
In common practice, there may be additional encapsulation headers
inserted by various forms of Layer 2 tunnels on the path to an on-
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link neighbor. Such tunnels SHOULD be instrumented to accommodate
the native MTU of the underlying interface, but in some cases it may
be prudent to reduce the size of the underlying interface MTU to
allow room for L2 encapsulation. Especially for underlying links
with low-end performance characteristics, it is imperative that
packets that successfully traverse the underlying link are not
dropped in the network due to a size restriction.
In a preferred approach, the AERO interface MTU should be set to a
value no smaller than the largest MTU among all underlying
interfaces. The AERO interface itself then MUST return locally-
generated ICMPv6 "Packet Too Big" messages for packets that are too
large to traverse the selected underlying interface in one piece.
This ensures that the MTU is adaptive and reflects the underlying
interface used for a given data flow.
Alternatively, the AERO interface MTU may be determined as the
minimum MTU among all underlying interfaces. However, this may
result in under-utilization of robust underlying interfaces after a
low-end underlying interface has degraded the common minimum MTU.
For example, if the underlying interfaces have MTUs 1500, 1472 and
1400, then the minimum AERO interface MTU is 1400.
If any underlying interface has an MTU smaller than 1280, the AERO
interface MUST either perform IPv6 fragmentation when using this
interface or disable the underlying interface.
The MTU for an underlying interface is normally determined from
information provided either statically or dynamically when the
interface becomes active. If an underlying interface MTU dynamically
reports an MTU smaller than any minimum MTU already determined then
the AERO interface MUST either perform IPv6 fragmentation when using
this interface, or disable the underlying interface.
The AERO interface MAY also receive an RA with an MTU option. If the
advertised MTU is no larger than 1500, the AERO interface MTU is set
to the new value and the AERO interface MUST either perform IPv6
fragmentation over any underlying interface having a smaller MTU or
disable the underlying interface.
If the advertised MTU is larger than 1500, the AERO interface sets
the new value and disables any underlying interface having a smaller
MTU instead of fragmenting, since IPv6 destinations are not required
to reassemble more than 1500 bytes.
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6. Frame Format
AERO interfaces transmit IPv6 packets according to the frame format
of the underlying interface. For example, for an Ethernet interface
the frame format is exactly as specified in [RFC2464], for an IPv6
tunnel over IPv4 the frame format is exactly as specified in
[RFC4213], etc.
7. Link-Local Addresses
A MN's AERO address is an IPv6 link-local address with an interface
identifier based on its assigned MNP. AERO addresses begin with the
prefix fe80::/64 followed by a 64-bit prefix taken from the MNP. For
example, for the MNP:
2001:db8:1000:2000::/56
the corresponding AERO addresses are:
fe80::2001:db8:1000:2000
fe80::2001:db8:1000:2001
fe80::2001:db8:1000:2002
... etc. ...
fe80::2001:db8:1000:20ff
When the MN configures AERO addresses from its MNP, the lowest-
numbered AERO address serves as the "base" address (for example, for
the MNP 2001:db8:1000:2000::/56 the base AERO address is
fe80::2001:db8:1000:2000). MNs and routers use the base address for
the purpose of maintaining neighbor cache entries, but the MN accepts
packets destined to all AERO addresses as equivalent.
A router's AERO address is allocated from the range fe80::/96, and
MUST be managed for uniqueness by the AERO link administrative
authority. The lower 32 bits of the AERO address includes a unique
integer value, e.g., fe80::1, fe80::2, fe80::3, etc. The address
fe80:: is reserved as the IPv6 link-local Subnet Router Anycast
address [RFC4291], and the address fe80::ffff:ffff is reserved as the
unspecified AERO address; hence, these values are not available for
general assignment.
For multi-segment AERO links, the routers of each segment MUST assign
AERO addresses that are unique among all routers on the (collective)
link. Although the address assignment policy is completely at the
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discretion of the AERO link administrative authority, a useful
technique may be to assign a different aggregated portion of the
fe80::/96 prefix to each segment, e.g., fe80::/120, fe80::0100/120,
fe80::0200/120, etc.
8. Address Mapping - Unicast
AERO interfaces maintain a neighbor cache for tracking per-neighbor
state the same as for any interface. AERO interfaces use standard
IPv6 Neighbor Discovery (ND) messages including Router Solicitation
(RS), Router Advertisement (RA), Neighbor Solicitation (NS), Neighbor
Advertisement (NA) and Redirect. AERO interface ND messages may
include zero or more Source/Target Link-Layer Address Options (S/
TLLAOs) formatted as shown in Figure 2:
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 = 5 | Prefix Length |R|D|X|T| Resvd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID | Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Link-Layer Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|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 2: AERO Source/Target Link-Layer Address Option (S/TLLAO)
Format
In this format:
o Type is set to '1' for SLLAO or '2' for TLLAO.
o Length is set to the constant value '5' (i.e., 5 units of 8
octets).
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o Prefix Length is set to the MNP prefix length for the AERO address
found in the source (RS), destination (RA) or target (NA) address
of an ND message used for the purpose of asserting an MNP;
otherwise set to 0. If the message contains multiple SLLAOs, only
the Prefix Length value in the first SLLAO is consulted and the
values in other SLLAOs are ignored. For RS messages, the router
creates a neighbor cache entry and announces the MNP in the
routing system, then returns an RA with Router Lifetime set to the
MNP assertion lifetime.
o R (the "Release" bit) is set to '1' in the SLLAO of an RS message
sent for the purpose of withdrawing an MNP; otherwise, set to '0'.
If the message contains multiple SLLAOs, only the R value in the
first SLLAO is consulted and the values in other SLLAOs are
ignored. The router withdraws the MNP, then returns an RA with
Router Lifetime set to '0'.
o D (the "Disable" bit) is set to '1' in the S/TLLAOs of an RS/NA
message for each Interface ID that is to be disabled in the
recipient's neighbor cache entry; otherwise, set to '0'. If the
message contains an S/TLLAO with D=1 and Interface ID 255, the
node disables the entire neighbor cache entry. If the message
contains multiple S/TLLAOs the D value in each S/TLLAO is
consulted.
o X (the "proXy" bit) is set to '1' in the SLLAO of an RS/RA message
when there is a proxy in the path; otherwise, set to '0'. If the
message contains multiple SLLAOs, only the X value in the first
SLLAO is consulted and the values in other SLLAOs are ignored.
o T (the "Translator" bit) is set to '1' in the SLLAO of an RA
message if there is a link-layer address translator in the path;
otherwise, set to '0'. If the message contains multiple SLLAOs,
only the T value in the first SLLAO is consulted and the values in
other SLLAOs are ignored.
o Resvd is set to the value '0' on transmission and ignored on
receipt.
o Interface ID is set to a 16-bit integer value corresponding to a
specific underlying interface. Once the MN has assigned an
Interface ID to an underlying interface, the assignment MUST
remain unchanged until the MN disables the AERO interface. The
value '255' is reserved as the router Interface ID, i.e., routers
MUST use Interface ID '255', and MNs MUST number their Interface
IDs with values in the range of 0-254.
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o Port Number and Link-Layer Address are set to the addresses
assigned to the underlying interface, or to '0' when the addresses
are left unspecified. For transmission over physical interfaces
such as Ethernet, the Link-Layer Address is set to the same format
as in the appropriate interface specification (e.g., IPv6 over
Ethernet [RFC2464]) beginning with the lowest-numbered byte of the
field and ending in trailing null padding to a total of 16 bytes.
For transmission over tunnel interfaces, the Link-Layer address is
set to an IPv6 address for IPv6 encapsulation or an IPv4-mapped
IPv6 address for IPv4 encapsulation. When TCP or UDP are used as
part of the encapsulation, Port Number is set to the encapsulation
protocol port number; otherwise, set to '0'.
o P(i) is a set of Preferences that correspond to the 64
Differentiated Service Code Point (DSCP) values [RFC2474]. Each
P(i) is set to the value '0' ("disabled"), '1' ("low"), '2'
("medium") or '3' ("high") to indicate a QoS preference level for
underlying interface selection purposes.
MNs such as aircraft typically have many wireless data link types
(e.g. satellite-based, cellular, terrestrial, air-to-air directional,
etc.) with diverse performance, cost and availability properties.
From the perspective of ND, the AERO interface would therefore appear
to have multiple link-layer addresses. In that case, ND messages MAY
include multiple S/TLLAOs -- each with an Interface ID that
corresponds to a specific underlying interface.
When the MN includes S/TLLAOs solely for the purpose of announcing
new QoS preferences, it sets both Port Number and Link-Layer Address
to 0 to indicate that the addresses are not to be updated in the
router's neighbor cache.
When an ND message includes multiple S/TLLAOs, the first S/TLLAO MUST
correspond to the underlying interface used to transmit the message.
Note that this S/TLLAO format includes network-layer information
(e.g., Prefix Length) in a link-layer option. This is due to the
fact that it is difficult to standardize new IPv6 ND options in a
timely fashion. An experimental proposal defines a "Universal RA
Option" intended for carrying generic network-layer information in
RS/RA messages [I-D.troan-6man-universal-ra-option]. However, there
is no way at this time to predict how long the experiment would take
nor whether it will be successful.
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9. Address Mapping - Multicast
When the underlying network does not support multicast, aircraft map
link-scoped multicast addresses to the link-layer address of a
router, which acts as a multicast forwarding agent. The mobile
router on board the aircraft also serves as an IGMP/MLD Proxy for its
EUNs and/or hosted applications per [RFC4605] while using the link-
layer address of the router as the link-layer address for all
multicast packets.
When the underlying network supports multicast, AERO interfaces use
the multicast address mapping specification found in [RFC2529] for
IPv4 underlying networks and use a TBD site-scoped multicast mapping
for IPv6 underlying networks. In that case, border routers must
ensure that the encapsulated site-scoped multicast packets do not
leak outside of the AERO link.
10. Router Discovery and MNP Assertion
MNs and routers coordinate their MNP assertions and per-link
parameters through RS/RA exchanges, and use ND messages to maintain
neighbor cache entries. Routers configure their AERO interfaces as
advertising interfaces, and therefore send unicast RA messages with
configuration information in response to a MN's RS message.
Thereafter, the MN sends additional RS messages to the router's
unicast address to refresh MNP and/or router lifetimes.
To assert an MNP, the MN sends an RS message over any underlying
interface with its base AERO address as the source address, all-
routers multicast as the destination address and with an SLLAO with a
valid Prefix Length for the MNP. The SLLAO also contains valid
Interface ID and P(i) values appropriate for the underlying
interface. When the router receives the RS message it injects the
MNP into the routing system if the prefix assertion was acceptable,
then registers the new Interface ID, Port Number, Link-Layer Address
and P(i) values in a neighbor cache entry. The router then returns
an RA with its AERO address as the source address, the AERO address
of the MN as the destination address and with Router Lifetime set to
a non-zero value if the MNP assertion was accepted; otherwise set to
zero. The message also includes an SLLAO with Prefix Length set to
the length of the MNP assertion.
After the MN receives the RA confirming the MNP assertion, it
registers each additional underlying interface with the router by
sending an RS over the underlying interface with its base AERO
address as the source address, the router's AERO address as the
destination address, and with an SLLAO with Prefix Length set to 0.
The SLLAO also contains valid Interface ID and P(i) values
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appropriate for the underlying interface. When the router receives
the RS message it registers the new Interface ID, Port Number, Link-
Layer Address and P(i) values in the neighbor cache already
established during MNP assertion. The router then returns an RA
message with its AERO address as the source address, the AERO address
of the MN as the destination address and with Router Lifetime set to
a non-zero value. The message also includes an SLLAO with Prefix
Length set to 0.
The MN is responsible for retrying each RS/RA exchange up to
MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL
seconds until an RA is received. If no RA is received, the MN
declares the underlying interface unreachable, but MAY try again
later (e.g., if underlying link conditions become more favorable).
MNs that do not need to assert MNP, Port Number, Link-Layer Address,
Interface ID or P(i) values MAY omit SLLAOs in RS messages.
Responding routers MAY also omit SLLAOs in the corresponding RAs.
11. IANA Considerations
No IANA actions are required.
12. Security Considerations
Security considerations are the same as defined for the underlying
interface types, and readers are referred to the appropriate
underlying interface specifications.
IPv6 and IPv6 ND security considerations also apply, and are
specified in the normative references.
13. Acknowledgements
This document was prepared per the consensus decision at the 8th
Conference of the International Civil Aviation Organization (ICAO)
Working Group-I Mobility Subgroup on March 22, 2019. Attendees and
contributors included: Guray Acar, Danny Bharj, Francois D'Humieres,
Pavel Drasil, Nikos Fistas, Giovanni Garofolo, Vaughn Maiolla, Tom
McParland, Victor Moreno, Madhu Niraula, Brent Phillips, Liviu
Popescu, Jacky Pouzet, Aloke Roy, Greg Saccone, Robert Segers,
Stephane Tamalet, Fred Templin, Bela Varkonyi, Tony Whyman, and
Dongsong Zeng.
.
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14. References
14.1. 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>.
[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>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[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>.
[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>.
14.2. Informative References
[I-D.troan-6man-universal-ra-option]
Troan, O., "The Universal IPv6 Router Advertisement Option
(experiment)", draft-troan-6man-universal-ra-option-01
(work in progress), December 2018.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
<https://www.rfc-editor.org/info/rfc2464>.
[RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
Domains without Explicit Tunnels", RFC 2529,
DOI 10.17487/RFC2529, March 1999,
<https://www.rfc-editor.org/info/rfc2529>.
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[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213,
DOI 10.17487/RFC4213, October 2005,
<https://www.rfc-editor.org/info/rfc4213>.
[RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick,
"Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding
("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605,
August 2006, <https://www.rfc-editor.org/info/rfc4605>.
[RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface
Support for IP Hosts with Multi-Access Support", RFC 7847,
DOI 10.17487/RFC7847, May 2016,
<https://www.rfc-editor.org/info/rfc7847>.
Appendix A. S/TLLAO Extensions for Special-Purpose Links
The S/TLLAO format specified in Section 8 includes a Length value of
5 (i.e., 5 units of 8 octets). However, special-purpose AERO links
may extend the basic format to include additional fields and a Length
value larger than 5.
For example, adaptation of AERO to the Aeronautical
Telecommunications Network with Internet Protocol Services (ATN/IPS)
includes link selection preferences based on transport port numbers
in addition to the existing DSCP-based preferences. ATN/IPS nodes
maintain a map of transport port numbers to 64 possible preference
fields, e.g., TCP port 22 maps to preference field 8, TCP port 443
maps to preference field 20, UDP port 8060 maps to preference field
34, etc. The extended S/TLLAO format for ATN/IPS is shown in
Figure 3, where the Length value is 7 and the 'Q(i)' fields provide
link preferences for the corresponding transport port number.
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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 = 7 | Prefix Length |R|D|X|T| Resvd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID | Port Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Link-Layer Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|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|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Q00|Q01|Q02|Q03|Q04|Q05|Q06|Q07|Q08|Q09|Q10|Q11|Q12|Q13|Q14|Q15|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Q16|Q17|Q18|Q19|Q20|Q21|Q22|Q23|Q24|Q25|Q26|Q27|Q28|Q29|Q30|Q31|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Q32|Q33|Q34|Q35|Q36|Q37|Q38|Q39|Q40|Q41|Q42|Q43|Q44|Q45|Q46|Q47|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Q48|Q49|Q50|Q51|Q52|Q53|Q54|Q55|Q56|Q57|Q58|Q59|Q60|Q61|Q62|Q63|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: ATN/IPS Extended S/TLLAO Format
Appendix B. Change Log
<< RFC Editor - remove prior to publication >>
First draft version (draft-templin-atn-aero-interface-00):
o Draft based on consensus decision of ICAO Working Group I Mobility
Subgroup March 22, 2019.
Authors' Addresses
Templin & Whyman Expires September 30, 2019 [Page 14]
Internet-Draft IPv6 over AERO Interfaces March 2019
Fred L. Templin (editor)
Boeing Research & Technology
P.O. Box 3707
Seattle, WA 98124
USA
Email: fltemplin@acm.org
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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