Satellite Semantic Addressing for Satellite Constellation
draft-lhan-satellite-semantic-addressing-01
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| Authors | Lin Han , Richard Li , Alvaro Retana , Meiling Chen , Ning Wang | ||
| Last updated | 2022-03-06 (Latest revision 2021-10-19) | ||
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draft-lhan-satellite-semantic-addressing-01
Network Working Group L. Han, Ed.
Internet-Draft R. Li
Intended status: Informational A. Retana
Expires: 7 September 2022 Futurewei Technologies, Inc.
M. Chen
China Mobile
N. Wang
University of Surrey
6 March 2022
Satellite Semantic Addressing for Satellite Constellation
draft-lhan-satellite-semantic-addressing-01
Abstract
This document presents a semantic addressing method for satellites in
satellite constellation connecting with Internet. The satellite
semantic address can indicate the relative position of satellites in
a constellation. The address can be used with traditional IP address
or MAC address or used independently for IP routing and switching.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 7 September 2022.
Copyright Notice
Copyright (c) 2022 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
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Basics of Satellite Constellation and Satellite Orbit . . . . 5
4.1. Satellite Orbit . . . . . . . . . . . . . . . . . . . . . 5
4.2. Satellite Constellation Compositions . . . . . . . . . . 6
4.3. Communication between Satellites by ISL . . . . . . . . . 7
5. Addressing of Satellite . . . . . . . . . . . . . . . . . . . 9
5.1. Indexes of Satellite . . . . . . . . . . . . . . . . . . 9
5.2. The Range of Satellite Indexes . . . . . . . . . . . . . 12
5.3. Other Info for satellite addressing . . . . . . . . . . . 13
5.4. Encoding of Satellite Semantic Address . . . . . . . . . 14
5.5. Link Identification by Satellite Semantic Address . . . . 16
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
Satellite constellation technologies for Internet are emerging and
expected to provide Internet service like the traditional wired
network on the ground. A typical satellite constellation will have
couple of thousands or over ten thousand of LEO and/or VLEO.
Satellites in a constellation will be connected to adjacent
satellites by Inter-Satellite-Links (ISL), and/or connected to ground
station by microwave or laser links. ISL is still in research stage
and will be deployed soon. This memo is for the satellite networking
with the use of ISL.
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The memo proposes to use some indexes to represent a satellite's
orbit information. The indexes can form satellite semantic address,
the address can then be embedded into IPv6 address or MAC address for
IP routing and switching. The address can also be used independently
if the shorter than 128-bit length of IP address is accepted. As an
internal address for satellite network, it only applies to satellites
that will form a constellation to transport Internet traffic between
ground stations and will not be populated to Internet by BGP.
2. Terminology
LEO Low Earth Orbit with the altitude from 180 km to
2000 km.
VLEO Very Low Earth Orbit with the altitude below 450 km
GEO Geosynchronous orbit with the altitude 35786 km
ISL Inter Satellite Link
ISLL Inter Satellite Laser Link
3D Three Dimensional
GS Ground Station, a device on ground connecting the
satellite. In the document, GS will hypothetically
provide L2 and/or L3 functionality in addition to
process/send/receive radio wave. It might be
different as the reality that the device to
process/send/receive radio wave and the device to
provide L2 and/or L3 functionality could be
separated.
SGS Source ground station. For a specified flow, a
ground station that will send data to a satellite
through its uplink.
DGS Destination ground station. For a specified flow,
a ground station that is connected to a local
network or Internet, it will receive data from a
satellite through its downlink and then forward to
a local network or Internet.
L1 Layer 1, or Physical Layer in OSI model [OSI-Model]
L2 Layer 2, or Data Link Layer in OSI model
[OSI-Model]
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L3 Layer 3, or Network Layer in OSI model [OSI-Model],
it is also called IP layer in TCP/IP model
BGP Border Gateway Protocol [RFC4271]
IGP Interior gateway protocol, examples of IGPs include
Open Shortest Path First (OSPF [RFC2328]), Routing
Information Protocol (RIP [RFC2453]), Intermediate
System to Intermediate System (IS-IS [RFC7142]) and
Enhanced Interior Gateway Routing Protocol (EIGRP
[RFC7868]).
3. Overview
For IP based satellite networking, the topology is very dynamic and
the traditional IGP and BGP based routing technologies will face
challenges according to the analysis in
[I-D.lhan-problems-requirements-satellite-net]. From the paper, we
can easily categorize satellite links as two types, steady and un-
steady. For un-steady links, the link status will be flipping every
couple of minutes.
Section 5.5 has more details about how to identify different links.
Some researches have been done to handle such fast changed
topologies. one method to overcome the difficulties for routing with
un-steady links is to only use the steady links, and get rid of un-
steady links unless it is necessary. For example, for real
deployment, only links between satellite and ground stations are
mandatory to use, other un-steady links can be avoided in routing and
switching algorithms. [Routing-for-LEO] proposed to calculate the
shortest path by avoiding un-steady links in polar area and links
crossing Seam line since satellites will move in the opposite
direction crossing the Seam line.
Traditionally, to establish an IP network for satellites, each
satellite and its interface between satellites and to ground stations
have to be assigned IP addresses (IPv4 or IPv6). The IP address can
be either private or public. IP address itself does not mean
anything except routing prefix and interface identifier [RFC8200].
To utilize the satellite relative position for routing, it is desired
that there is an easy way to identify the relative positions of
different satellites and identify un-steady links quickly. The
traditional IP address cannot provide such functionality unless we
have the real-time processing for 3D coordinates of satellites to
figure out the relative positions of each satellite, and some math
calculation and dynamic database are also needed in routing algorithm
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to check if a link is steady or not. This will introduce extra data
exchanged for routing protocols and burden for the computation in
every satellite. Considering the ISL link speed (up to 10G for
2000km) and hardware cost (Radiation-hardened semiconductor
components are needed) in satellite are more constraint than for
network device on ground, it is expected to simplify the routing
algorithm, reduce the requirement of ISL, onboard CPU and memory.
The document proposes to form a semantic address by satellite orbit
information, and then embedded it into a proper IP address. The IP
address of IGP neighbors can directly tell the relative position of
different satellites and if links between two satellites are stead or
not.
The document does not describe the details how the semantic address
is used to improve routing and switching or new routing protocols,
those will be addressed in different documents.
4. Basics of Satellite Constellation and Satellite Orbit
This section will introduce some basics for satellite such as orbit
parameters.
4.1. Satellite Orbit
The orbit of a satellite can be either circular or ecliptic, it can
be described by following Keplerian elements [KeplerianElement]:
1. Inclination (i)
2. Longitude of the ascending node (Omega)
3. Eccentricity (e)
4. Semimajor axis (a)
5. Argument of periapsis (omega)
6. True anomaly (nu)
The circular orbit is widely used by proposals of satellite
constellation from different companies and countries.
For a circular orbit, we will have:
* Eccentricity e = 0
* Semimajor axis a = Altitude of satellite
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* Argument of periapsis omega = 90 degree
So, three parameters, Altitude, Inclination and Longitude of the
ascending node, will be enough to describe the orbit. The satellite
will move in a constant speed and True anomaly (nu) can be easily
calculated after the epoch time is defined.
4.2. Satellite Constellation Compositions
One satellite constellation may be composed of many satellites (LEO
and VLEO), but normally all satellites are grouped in a certain order
that is never changed during the life of satellite constellation.
Each satellite constellation's orbits parameters described in
Section 4.1 must be approved by regulator and cannot be changed
either. Follows are characters of one satellite constellation:
1. One Satellite Constellation is composed of couple of shell groups
of satellites.
2. Same shell group of satellite will have the same altitude and
inclination.
3. The total N orbit planes in the same shell group of satellites
will be evenly distributed by the same interval of Longitude of
the ascending node (Omega). The interval equals to (360 degree/
N). As a result, all orbit planes in the same shell group will
effectively form a shell to cover earth (there will be a coverage
hole for the shell if the inclination angle is less than 90
degree).
4. Each orbit plane in the same shell group will have the same
number of satellites, all satellites in the same orbit plane will
be evenly distributed angularly in the orbit plane.
5. All satellites in the same shell group are moving in the same
circular direction within the same orbit plane. As a result, at
any location on earth, we can see there will have two group of
satellites moving on the opposite direction. One group moves
from south to north, and another group moves from north to south.
Section 5.5 has more details.
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4.3. Communication between Satellites by ISL
When ISL is used for the communication between satellites, each
satellite will have a fixed number of links to connect to its
neighbor. Due to the cost of ISL and the constraints of power supply
on satellite, the number of ISL is normally limited to connect to its
closest neighbors. In 3D space, each satellite may have six types of
adjacent satellites, each type represents one direction. The number
of adjacent neighbors in one direction is dependent on the number of
deployment of ISL device on satellites, for example, the laser
transmitter and receiver for ISLL. Figure 1 illustrates satellite S0
and its adjacent neighbors.
/ / /
/ / /
/ / /
S7 S8 S9
/ / /
/ / /
/ / /
/ S1 /
S5 / S3
/ / /
/ S0 /
/ / /
S6 / S4
/ S2 /
/ / /
/ / /
/ / /
S10 S11 S12
/ / / ^ Moving direction
/ / / /
/ / / /
orbit orbit orbit
Figure 1: Satellite S0 and its adjacent neighbors
All adjacent satellites of S0 in Figure 1 are listed below:
1. The front adjacent satellite S1 that is on the same orbit plane
as S0.
2. The back adjacent satellite S2 that is on the same orbit plane as
S0
3. The right adjacent satellites S3 and S4 that are on the right
orbit plane of S0
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4. The left adjacent satellites S5 and S6 that are on the left orbit
plane of S0
5. The above adjacent satellites S7 to S9 that are on the above
orbit plane of S0
6. The below adjacent satellite S10 to S12 that are on the below
orbit of plane S0
The relative position of adjacent satellites will directly determine
the quality of ISL and communication. From the analysis in
[I-D.lhan-problems-requirements-satellite-net], The speed of
satellite is only related to the altitude of the satellite (on
circular orbit), all satellites with a same altitude will move with
the same speed. So, in above adjacent satellites, some adjacent
satellite's relative positions are steady and the ISL can be alive
without interruption caused by movement. Some adjacent satellites
relative positions are changing quickly, the ISL may be down since
the distance may become out of reach for the laser of ISL, or the
quick changed positions of two satellite make the tracking of laser
too hard. Below are details:
* The relative position of satellites in the same orbit plane will
be the steadiest.
* The relative position of satellites in the direct neighbor orbit
planes in the same shell group and moving in the same direction
will be steady at equator area, but will be changing when two
orbits meet on the polar area. Whether the link status will be
flipping depends on the tracking technology and the range of laser
pointing angle of ISL. See Figure 2.
* The relative position of satellites in the neighbor orbit planes
in the same shell group but moving in the different direction will
not be steady at all times. More details are explained in
Figure 8
* The relative position of satellites in the neighbor orbit planes
in the different shell group will be dependent on the difference
of altitude and inclination. This has been analyzed in
[I-D.lhan-problems-requirements-satellite-net].
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\ /
P3 P4
\ /
\/
/\
/ \
P1 P2
/ \
* Two satellites S1 and S2 are at position P1 and P2 at time T1
* S1's right facing ISL connected to S2's left facing ISL
* S1 and S2 move to the position P4 and P3 at time T2
* S1's left facing ISL connected to S2's right facing ISL
* So, if the range of laser pointing angle is 360 degree and
tracking technology supports, the ISL will not be flipping
after passing polar area; Otherwise, the link will be flipping
Figure 2: Satellite's Position and ISL Change at Polar Area
5. Addressing of Satellite
When ISL is deployed in satellite constellation, all satellites in
the constellation can form a network like the wired network on
ground. Due to the big number of satellites in a constellation, the
network could be either L2 or L3. The document proposes to use L3
network for better scalability.
When satellites form a L3 network, it is expected that IP address is
needed for each satellite and its ISLs.
While the traditional IP address can still be used for satellite
network, the document proposes an alternative new method for
satellite's addressing system. The new addressing system can
indicate a satellite's orbit info such as shell group index, orbit
plane index and satellite index. This will make the adjacent
satellite identification for link status easier and benefit the
routing algorithms.
5.1. Indexes of Satellite
As described in Section 4.2, one satellite has three important orbit
related information as described below.
1. Index for the shell group of satellites in a satellite
constellation
2. Index for the orbit plane in a shell group of satellites
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3. Index for the satellite in an orbit plane
It should be noted that for all type of indexes, it is up to the
owner to assign the index number. There is no rule for which one
should be assigned with which number. The only important rule is
that all index number should be in sequential to reflect its relative
order and position with others. Below is an example of assignment
rules:
1. The 1st satellite launched in an orbit plane can be assigned for
the 1st satellite index (0), the incremental direction of the
satellite index in the same orbit plane is the incremental
direction of "Argument of periapsis (omega)"
2. The 1st orbit plane established can be assigned for the 1st orbit
plane index (0), the incremental direction of the orbit plane
index is the incremental direction of "Longitude of the ascending
node (Omega)".
3. The shell group of satellites with the lowest altitude can be
assigned for the 1st shell group index (0), the incremental
direction of shell group index is the incremental direction of
altitude.
Figure 3 and Figure 4 illustrate three types of indexes for
satellite.
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/ / / \
/ / / |
/ / / |
S S S > shell group3
/ / / |
/ / / |
/ / / /
/ S / \
S / S |
/ / / |
/ S / > shell group2
/ / / |
S / S |
/ S / /
/ / / \
/ / / |
/ / / |
S S S > shell group1
/ / / |
/ / / |
/ / / /
orbit orbit orbit ----> Earth self-rotation
plane1 plane2 plane3
Figure 3: Shell Group and Orbit Plane Indexes for Satellites
Shell Group and Orbit Plane Indexes for Satellites
, - ~ S1 ~ - ,
S2 ' ' S8
, ,
, ,
, , Indexed
S3 S7 <-- satellite
, , in one orbit plane
, ,
, , ^ move direction
S4 , S6 /
' - , _ S5_ , ' /
Figure 4
Three type of Index for satellites
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5.2. The Range of Satellite Indexes
The ranges of different satellite indexes will determine the range
the dedicated field for semantic address. The maximum indexes depend
on the number of shell group, orbit plane and satellite per orbit
plane. The number of orbit plane and satellite per orbit plane have
relationship with the coverage of a satellite constellation. There
are minimum numbers required to cover earth.
[I-D.lhan-problems-requirements-satellite-net] has given the detailed
math to estimate the minimal number required to cover the earth.
There are two key parameters that determine the minimal number of
satellite required. One is the elevation angle, another is the
altitude. SpaceLink has proposed two elevation angles, 25 and 35
degrees [SpaceX-Non-GEO]. The lowest LEO altitude can be 160km
according to [Lowest-LEO-ESA]. The Table 1 and Table 2 illustrate
the estimation for different altitude (As), the coverage radius (Rc),
the minimal required number of orbit planes (No) and satellite per
orbit plane (Ns). The elevation angle is 25 degree and 35 degrees
respectively.
+============+=======+=======+======+======+======+======+======+
| Parameters | VLEO1 | VLEO2 | LEO1 | LEO2 | LEO3 | LEO4 | LEO5 |
+============+=======+=======+======+======+======+======+======+
| As(km) | 160 | 300 | 600 | 900 | 1200 | 1500 | 2000 |
+------------+-------+-------+------+------+------+------+------+
| Rc(km) | 318 | 562 | 1009 | 1382 | 1702 | 1981 | 2379 |
+------------+-------+-------+------+------+------+------+------+
| Ns | 73 | 42 | 23 | 17 | 14 | 12 | 10 |
+------------+-------+-------+------+------+------+------+------+
| No | 85 | 48 | 27 | 20 | 16 | 14 | 12 |
+------------+-------+-------+------+------+------+------+------+
Table 1: Satellite coverage (Rc), minimal number of orbit
plane (No) and satellite (Ns) per orbit plane for different
LEO/VLEOs, Elevation angle = 25 degree
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+============+=======+=======+======+======+======+======+======+
| Parameters | VLEO1 | VLEO2 | LEO1 | LEO2 | LEO3 | LEO4 | LEO5 |
+============+=======+=======+======+======+======+======+======+
| As(km) | 160 | 300 | 600 | 900 | 1200 | 1500 | 2000 |
+------------+-------+-------+------+------+------+------+------+
| Rc(km) | 218 | 392 | 726 | 1015 | 1271 | 1498 | 1828 |
+------------+-------+-------+------+------+------+------+------+
| Ns | 107 | 59 | 32 | 23 | 19 | 16 | 13 |
+------------+-------+-------+------+------+------+------+------+
| No | 123 | 69 | 37 | 27 | 22 | 18 | 15 |
+------------+-------+-------+------+------+------+------+------+
Table 2: Satellite coverage (Rc), minimal number of orbit
plane (No) and satellite (Ns) per orbit for different LEO/
VLEOs, Elevation angle = 35 degree
The real deployment may be different as above analysis. Normally,
more satellites and orbit planes are used to provide better coverage.
So far, there are only two proposals available, one is StarLink,
another is from China Constellation. For proposals of [StarLink],
there are 7 shell groups, the number of orbit plane and satellites
per orbit plane in all shell groups are 72 and 58; For proposals of
[China-constellation], there are 7 shell groups, the number of orbit
plane and satellites per orbit plane in all shell groups are 60 and
60;
It should be noted that some technical parameters, such as the
inclination and altitude of orbit planes, in above proposals may be
changed during the long-time deployment period, but the total numbers
for indexes normally do not change.
From the above analysis, to be conservative, it is safe to conclude
that the range of all three satellite indexes are less than 256, or
8-bit number.
5.3. Other Info for satellite addressing
In addition to three satellite indexes described in Section 5.1,
other information is also important and can also be embedded into
satellite address:
1. The company or country code, or the owner code. In the future,
there may have multiple satellite constellations on the sky from
different organizations, and the inter-constellation
communication may become as normal that is similar to the network
on the ground. This code will be useful to distinguish different
satellite constellation and make the inter-constellation
communication possible. One satellite constellation will have
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one code assigned by international regulator (IANA or ITU).
Considering the limit of LEO orbits and the cost of satellite
constellations, the total number of satellite constellation is
very limited. So, the size of code is limited.
2. The Interface Index. This index is to identify the ISL or ISLL
for a satellite. As described in Section 4.3, the total number
of ISL is limited. So, the size of interface index is also
limited.
5.4. Encoding of Satellite Semantic Address
The encoding for satellite semantic address is dependent on what
routing and switching (L2 or L3 solution) technologies are used for
satellite networking, and finally dependent on the decision of IETF
community.
Follows are some initial proposals:
1. When satellite network is using L3 solution, the satellite
semantic address is encoded as the interface identifier (i.e.,
the rightmost 64 bits) of the IPv6 address for IPv6. Figure 5
shows the format of IPv6 Satellite Address.
2. When satellite network is using L2 solution, the satellite
semantic address can be embedded into the field of "Network
Interface Controller (NIC) Specific" in MAC address
[IEEE-MAC-Address]. But due to shorter space for NIC, the "Index
for the shell group" and "Index for Interface" will only have
4-bit. This is illustrated in Figure 6. This encoded MAC
address can also be used for L3 solution where the interface MAC
may be also needed to be configured for each ISL.
3. Recently, some works suggested to use Length Variable IP address
for routing and switching [Length-Variable-IP] or use flexible IP
address [I-D.jia-flex-ip-address-structure] or shorter IP address
[I-D.li-native-short-addresses] to solve some specific problems
that regular IPv6 is not very suitable. Satellite network also
belongs to such specific network. Due to the resource and cost
constraints and requirement for radiation hardened electronic
components, the ISL speed, on-board processor and memory are
limited in performance, power consumption and capacity compared
with network devices on ground. So, using IPv6 directly in
satellite network is not an optimal solution because IPv6 header
size is too long for such small network. From above analysis,
32-bit to 64-bit length of IP address is enough for satellite
networking. Using 128-bit IPv6 will consume more resource
especially the ISL bandwidth, processing power and memory, etc.
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If shorter than 128-bit IP address is accepted as IETF work, the
satellite semantic address can be categorized as a similar use
case. Figure 7 illustrates a 32-bit Semantic Satellite Address
format. The final coding for the shorter IP address can be
decided by the community. How to use the 32-bit Semantic
Satellite address can be addressed later on in different
document.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Subnet Prefix (64 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Owner Code | Shell_Index | Orbit_Index | Sat_Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Intf_Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Owner Code: Identifier for the owner of the constellation
Shell_Index: Index for the shell group of satellite in a satellite
constellation
Orbit_Index: Index for the orbit plane in a shell group of satellite
Sat_Index: Index for the satellite in an orbit plane
Intf_Index: Index for interface on a satellite
Reserved: 24-bits reserved
Figure 5: The IPv6 Satellite Address
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3 Octets 3 Octets
/---------^--------\ /--------^--------\
+-------------------+-------------------+
| OUI | Sat Address |
+-------------------+-------------------+
|
|
+-------------------------------+
|
|
v
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Shell | Orbit_Index | Sat_Index |Intf_Id|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OUI: Organizationally Unique Identifier assigned by IEEE
Shell: 4-bit Index for the shell group of satellite in a satellite
constellation
Orbit_Index: Index for the orbit plane in the group of satellite
Sat_Index: Index for the satellite in the orbit plane
Intf_Id: 4-bit Index for interface on a satellite
Figure 6: The MAC Satellite Address
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Owner Code | Shell_Index | Orbit_Index | Sat_Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Owner Code: Identifier for the owner of the constellation
Shell_Index: Index for the shell group of satellite in a satellite
constellation
Orbit_Index: Index for the orbit plane in a shell group of satellite
Sat_Index: Index for the satellite in an orbit plane
Figure 7: The 32-bit Semantic Satellite Address
5.5. Link Identification by Satellite Semantic Address
Using above satellite semantic addressing scheme, to identify steady
and un-steady links is as simple as below:
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Assuming:
1. The total number of satellites per orbit plane is M
2. The total number of orbit planes per shell group is N.
3. Two satellites have:
* Satellite Indexes as: Sat1_Index, Sat2_Index
* Orbit plane Indexes as: Orbit1_Index, Orbit2_Index
* Shell group Indexes as: Shell1_Index, Shell2_Index
Steady links:
1. The links between adjacent satellites on the same orbit plane,
or, the satellite indexes satisfy:
* Sat2_Index = Sat1_Index + 1, when Sat1_Index < M-1; Sat2_Index
= 0, when Sat1_Index = M-1; and
* Orbit1_Index = Orbit2_Index, Shell1_Index = Shell2_Index.
2. The links between satellites on adjacent orbit planes on the same
altitude. and two satellites are moving to the same direction,
or, the satellite indexes satisfy:
* Orbit2_Index = Orbit1_Index + 1, when Orbit1_Index < N-1;
Orbit2_Index = 0, when Orbit1_Index = N-1; and
* Shell1_Index = Shell2_Index.
* Sat1_Index and Sat2_Index may be equal or have difference,
depend on how the link is established.
Un-Steady links:
1. The links between satellite and ground stations.
2. The links between satellites on adjacent orbit planes on the same
altitude. Two satellites are moving to the different direction.
Or, the satellite indexes do not satisfy conditions described in
above #2 for Steady links.
3. The links between satellites on adjacent orbit planes on
different altitude. Or, the satellite indexes satisfy:
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* Shell1_Index != Shell2_Index.
Figure 8 illustrates the links for adjacent orbit planes (#2 for
Steady Link and Un-steady Link above). From the figure, it can be
noticed that some links may have shorter distance than steady link,
but they are unsteady. For example, the links between S1 and S4; S4
and S2; S2 and S5, etc.
i+N/2 i+1+N/2 i+2+N/2
/ \ / \ / \
/ \ / \ / \
S1............S2............S3 \
/ S4 ..........S5............S6
/ \ / \ / \
/ \ / \ / \
i-1 i i+1
* The total number of orbit planes are N
* The number (i-1, i, i+1,...) represents the Orbit index
* The bottom numbers (i-1, i, i+1) are for orbit planes on
which satellites (S1, S2, S3) are moving from bottom to up.
* The top numbers (i+N/2, i+1+N/2, i+2+N/2) are for orbit
planes on which satellites (S4, S5, S6) are moving from up
to bottom.
* Dot lines are the steady links
Figure 8: The links between satellites on adjacent orbit planes
6. IANA Considerations
This memo may include request to IANA for owner code, see
Section 5.4.
7. Contributors
8. Acknowledgements
9. References
9.1. Normative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
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[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC7142] Shand, M. and L. Ginsberg, "Reclassification of RFC 1142
to Historic", RFC 7142, DOI 10.17487/RFC7142, February
2014, <https://www.rfc-editor.org/info/rfc7142>.
[RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
DOI 10.17487/RFC2453, November 1998,
<https://www.rfc-editor.org/info/rfc2453>.
[RFC7868] Savage, D., Ng, J., Moore, S., Slice, D., Paluch, P., and
R. White, "Cisco's Enhanced Interior Gateway Routing
Protocol (EIGRP)", RFC 7868, DOI 10.17487/RFC7868, May
2016, <https://www.rfc-editor.org/info/rfc7868>.
[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>.
9.2. Informative References
[I-D.lhan-problems-requirements-satellite-net]
Han, L., Li, R., Retana, A., Chen, M., Su, L., and N.
Wang, "Problems and Requirements of Satellite
Constellation for Internet", Work in Progress, Internet-
Draft, draft-lhan-problems-requirements-satellite-net-02,
13 February 2022, <https://datatracker.ietf.org/doc/html/
draft-lhan-problems-requirements-satellite-net-02>.
[I-D.jia-flex-ip-address-structure]
Jia, Y., Chen, Z., and S. Jiang, "Flexible IP: An
Adaptable IP Address Structure", Work in Progress,
Internet-Draft, draft-jia-flex-ip-address-structure-00, 31
October 2020, <https://datatracker.ietf.org/doc/html/
draft-jia-flex-ip-address-structure-00>.
[I-D.li-native-short-addresses]
Li, G., Jiang, S., and D. E. 3rd, "Native Short Addresses
for the Internet Edge", Work in Progress, Internet-Draft,
draft-li-native-short-addresses-01, 25 May 2021,
<https://datatracker.ietf.org/doc/html/draft-li-native-
short-addresses-01>.
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[Routing-for-LEO]
E. Ekici, I. F. Akyildiz and M. D. Bender, ""Datagram
routing algorithm for LEO satellite networks," Proceedings
IEEE INFOCOM 2000. Conference on Computer Communications.
Nineteenth Annual Joint Conference of the IEEE Computer
and Communications Societies (Cat. No.00CH37064), 2000,
pp. 500-508 vol.2, doi: 10.1109/INFCOM.2000.832223.",
<https://ieeexplore.ieee.org/document/832223>.
[Length-Variable-IP]
Shoushou Ren, Delei Yu, Guangpeng Li, Shihui Hu, Ye Tian,
Xiangyang Gong, Robert Moskowitz, ""Routing and Addressing
with Length Variable IP Address," NEAT'19: Proceedings of
the ACM SIGCOMM 2019 Workshop on Networking for Emerging
Applications and Technologies, August 2019",
<https://doi.org/10.1145/3341558.3342204>.
[IEEE-MAC-Address]
"IEEE Std 802-2001 (PDF). The Institute of Electrical and
Electronics Engineers, Inc. (IEEE). 2002-02-07. p. 19.
ISBN 978-0-7381-2941-9. Retrieved 2011-09-08.",
<https://standards.ieee.org/getieee802/
download/802-2001.pdf>.
[Lowest-LEO-ESA]
"Lowest LEO by ESA",
<https://www.esa.int/ESA_Multimedia/Images/2020/03/Low_Ear
th_orbit#:~:text=A%20low%20Earth%20orbit%20(LEO,very%20far
%20above%20Earth's%20surface.>.
[KeplerianElement]
"Keplerian elements",
<https://en.wikipedia.org/wiki/Orbital_elements>.
[OSI-Model]
"OSI Model", <https://en.wikipedia.org/wiki/OSI_model>.
[StarLink] "Star Link", <https://en.wikipedia.org/wiki/Starlink>.
[China-constellation]
"China Constellation", <https://www.itu.int/ITU-
R/space/asreceived/Publication/DisplayPublication/23706>.
[SpaceX-Non-GEO]
"FCC report: SPACEX V-BAND NON-GEOSTATIONARY SATELLITE
SYSTEM", <https://fcc.report/IBFS/SAT-LOA-
20170301-00027/1190019.pdf>.
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Appendix A. Change Log
* Initial version, 10/19/2021
* 01 version, 02/28/2022
Authors' Addresses
Lin Han (editor)
Futurewei Technologies, Inc.
2330 Central Express Way
Santa Clara, CA 95050,
United States of America
Email: lhan@futurewei.com
Richard Li
Futurewei Technologies, Inc.
2330 Central Express Way
Santa Clara, CA 95050,
United States of America
Email: rli@futurewei.com
Alvaro Retana
Futurewei Technologies, Inc.
2330 Central Express Way
Santa Clara, CA 95050,
United States of America
Email: alvaro.retana@futurewei.com
Meiling Chen
China Mobile
32, Xuanwumen West
BeiJing 100053
China
Email: chenmeiling@chinamobile.com
Ning Wang
University of Surrey
Guildford
Surrey, GU2 7XH
United Kingdom
Email: n.wang@surrey.ac.uk
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