Network Working Group D. Farinacci
Internet-Draft lispers.net
Intended status: Experimental V. Moreno
Expires: October 3, 2022 P. Pillay-Esnault
Independent
April 1, 2022
LISP for Satellite Networks
draft-farinacci-lisp-satellite-network-00
Abstract
This specification describes how the LISP architecture and protocols
can be used over satellite network systems. The LISP overlay runs on
earth using the satellite network system in space as the underlay.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Mapping System . . . . . . . . . . . . . . . . . . . . . . . 7
5. EID Mobility . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Satellite RLOCs and Underlay Routing . . . . . . . . . . . . 7
7. Underlay Performance . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 10
Appendix B. Document Change Log . . . . . . . . . . . . . . . . 10
B.1. Changes to draft-farinacci-lisp-satellite-network-00 . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
This specification describes how a LISP overlay structure can run on
top of a satellite network underlay. The approach is similar to how
[I-D.haindl-lisp-gb-atn] is used in Aeronautical Telecommunications
Networks and [I-D.farinacci-lisp-mobile-network] is used in cellular
networks.
This satellite deployment use-case requires no changes to the LISP
architecture or standard protocol specifications. In addition, any
LISP implementations that run on a device with an existing satellite
interface does not need to be upgraded.
Even though an overlay should not concern itself with the operation
of an underlay, the requirements from
[I-D.lhan-problems-requirements-satellite-net] are considered but
outside the scope of this document.
The LISP overlay requirements are:
1. There will be no EID state in the satellite network underlay.
2. The satellite underlay is completely unaware of the overlay
running over it.
3. The overlay requires the underlay network to deliver packets to
RLOC addresses.
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4. The underlay network can transport IPv4 or IPv6 packets and can
be dual-stack.
5. When path optimization in the underlay is available, an RLOC-
record can be a source route of satellite hops.
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The diagram below illustrates a 4 satellite system where each have
Inter-Satellite-Links (ISLs) for connectivity between them and edge
satellites with RF links to Ground Stations. The EID connectivity to
the xTRs is achieved via typical IP network connectivity where EIDs
can be directly connected, one or more switch hops away, one or more
router hops away, or any combination.
in space (underlay)
+--------------------------------------------------------------+
| |
| sat ISL sat ISL sat ISL sat |
| ))*(( ------- ))*(( ------- ))*(( ------- ))*(( |
| | | |
| | | |
| |up/down RF-link up/down RF-link| |
| | | |
| | | |
+------|-----------------------------------------------|-------+
| |
| |
| on earth (overlay) |
+------|-----------------------------------------------|-------+
| | | |
| GS-xTR [mapping system] GS-xTR |
| / \ / \ |
| / \ / \ |
| / \ / \ |
| / \ / \ |
| EIDs ... EIDs EIDs ... EIDs |
| |
+--------------------------------------------------------------+
Overlay on Earth, Underlay in Space
The LISP mapping system runs on the earth-resident Internet and
requires reachability by xTRs before LISP encapsulation can occur
over the satellite network underlay.
EIDs are known only to the overlay xTR nodes. EIDs are not routable
or require state in the satellite network. This provides great value
for scaling and EID mobility.
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2. Definition of Terms
Inter-Satellite-Links (ISLs): are phased-array laser wireless links
that transmit within or across orbits in space to other
satellites. They are different than satellite downlinks which are
RF links to Ground-Stations.
xTR: is a LISP data-plane device. xTR is the general term for ITR,
ETR, or RTR. The formal and authoritative definition is in
[I-D.ietf-lisp-rfc6830bis]. When a LISP xTR runs on a ground
station device, it is called a GS-xTR.
Ground-Station (GS): is a device on the ground that has wireless
links to a satellite node in space
[I-D.lhan-problems-requirements-satellite-net]. When a Ground-
Station is an LISP xTR, it encapsulates and decapsulates packets
sent and received on satellite links according to the forwarding
procedures in [I-D.ietf-lisp-rfc6830bis] and
[I-D.ietf-lisp-rfc6833bis]. A GS can also be part of the
satellite network system but isn't deployed as a GS-xTR. In this
scenario, the GS is part of the underlay and assumes the satellite
network system, with its attached ground stations, deliver RLOC
addressed packets. When a satellite is in relay mode (not using
ISLs), a LISP RTR can be used to support traffic engineering where
a GS-ITR encapsulates through a single satellite hop to a GS-RTR
which decapsulates and re-encapsulates through another single
satellite hop to a GS-ETR. See [I-D.ietf-lisp-te] for details,
and how LISP-TE can also be used with multiple satellite hops.
source-GS-xTR: is the LISP ITR which does a mapping system lookup to
obtain and cache the destination-RLOC for the destination-EID. It
then encapsulates the packet and sends it on the uplink whatever
satellite that is in coverage range.
destination-GS-xTR: is the LISP ETR which receives a LISP
encapsulated packet on the downlink from the satellite that is in
coverage range over it. The outer header is stripped and packet
is delivered to local EID on the ground.
EID: defined as an Endpoint-ID in [I-D.ietf-lisp-rfc6830bis]. An
EID is assigned to devices that reside behind GS-xTRs and are
registered to the LISP mapping system with a satellite network
address which is used as an RLOC.
RLOC: defined as a Routing Locator in [I-D.ietf-lisp-rfc6830bis].
Within the scope of this specification, the RLOC is the satellite
network address of a GS-xTR where the satellite network knows how
to forward packets to this RLOC address.
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3. Overview
Here is how a packet flow sequence occurs from a source-EID to a
destination-EID when the underlay is a satellite network:
1. source-EID originates an IP packet to a destination-EID. The
addresses in the packet are EIDs.
2. The packet travels to the GS-xTR (source-GS-xTR) via traditional
IP routing.
3. The source-GS-xTR does a map-cache lookup for destination-EID to
obtain the RLOC for the destination-GS-xTR.
4. If map-cache lookup fails, a mapping system lookup is performed
for destination-EID.
5. The source-GS-xTR LISP encapsulates the packet and sends it on
the uplink to the satellite. The RLOC addresses in the outer
header are source-GS-xTR and destination-GS-xTR.
6. The satellite network delivers the packet to Ground-Station
addressed as destination-GS-xTR.
7. The destination-GS-xTR decapsulates the LISP packet by stripping
the outer header and delivering the packet to the destination-EID
on the ground.
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4. Mapping System
The LISP mapping system holds EID-to-RLOC-set mappings. They are
kept up to date by GS-xTRs and all the mechanisms from
[I-D.ietf-lisp-rfc6833bis] are available for use. The mappings can
contain RLOCs that are not GS-xTRs thereby allowing load-splitting
between both satellite and terrestrial paths. The RLOC-set can also
contain multicast RLOCs that can be reachable via satellite or
terrestrial paths.
All of IPv4, IPv6, and MAC EIDs can be registered to the mapping
system to create multi-address-family L3 overlays as well as L2
overlays on the satellite underlay. That is, GS-xTR RLOCs can be
used with these EID address types.
Since the satellite network is not required to carry all routes that
are earth-based, the LISP critical infrastructure will not be
reachable by satellite nodes. Therefore, the mapping system must be
earth-based so xTRs which are not GS-xTRs can register and lookup
mappings. Note the satellite network is only required to carry
routes for GS-xTR addresses.
When satellite connectivity changes from a GS-xTR within its coverage
range, the RLOC of the GS-xTR does not change. Therefore, there is
no need to update the mapping system when this happens. This
provides more scale to the total system since the LISP overlay is
providing a level of indirection.
5. EID Mobility
EID-mobility [I-D.ietf-lisp-eid-mobility] is supported so devices can
roam to other xTRs and are found by mapping system updates for remote
xTRs encapsulating to the EID. GS-xTRs learn EIDs on the ground
dynamically via the mechanisms in [I-D.ietf-lisp-eid-mobility].
6. Satellite RLOCs and Underlay Routing
The address format of a GS-xTR RLOC depends on the design of the
satellite network system. The LISP RLOC formatting is flexible to
accommodate new address types such as GPS coordinate based addressing
or other forms of satellite addressing
[I-D.lhan-satellite-semantic-addressing]. The only requirement is
that they are routable by the satellite network system.
If the satellite network supports IP forwarding and IP addresses are
assigned to the RF-links on the GS-xTRs, then the satellite network
just needs to make these "attachment point addresses" routable in the
satellite network routing system. And if the satellite network
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desires to scale the route state in its routing system, it can use
prefix aggregation, a local design matter to the satellite network
routing system. When this is the case, the RLOC is a standard AFI
encoded IPv4 or IPv6 address.
If the satellite network underlay supports a source-routing
mechanism, as suggested in [I-D.lhan-satellite-instructive-routing],
the same approach can be used as a LISP overlay on a terrestrial
underlay running Segment Routing [RFC8754]. The source-route is
encoded in an RLOC-record stored in the mapping system that is
formatted as a list of satellite hop addresses.
7. Underlay Performance
The RLOC probing procedures in [I-D.ietf-lisp-rfc6833bis] can provide
underlay telemetry measurement [I-D.farinacci-lisp-telemetry] so the
overlay can tell how well the satellite network is performing. And
if the underlay under performs or telemetry metrics change, the GS-
xTR can select another RLOC, possibly to a terrestrial RLOC.
8. Security Considerations
There are no specific security considerations at this time for this
use-case. However, existing LISP security functionality documented
in [I-D.ietf-lisp-rfc6833bis], [I-D.ietf-lisp-sec],
[I-D.ietf-lisp-eid-anonymity], and [I-D.farinacci-lisp-ecdsa-auth]
can be used when the LISP overlay runs over a satellite network
underlay.
Data-plane encryption can be used to make the satellite underlay more
secure. See LISP Data-Plane Confidentiality [RFC8061] for more
details. This solution can work when packets take multiple satellite
hops and/or Ground-Station hops.
9. IANA Considerations
There are no requests for IANA at this time.
10. References
10.1. Normative References
[I-D.ietf-lisp-rfc6830bis]
Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos, "The Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-rfc6830bis-36 (work in progress), November
2020.
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[I-D.ietf-lisp-rfc6833bis]
Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
"Locator/ID Separation Protocol (LISP) Control-Plane",
draft-ietf-lisp-rfc6833bis-30 (work in progress), November
2020.
[I-D.ietf-lisp-sec]
Maino, F., Ermagan, V., Cabellos, A., and D. Saucez,
"LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-25 (work
in progress), December 2021.
[RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700,
DOI 10.17487/RFC1700, October 1994,
<https://www.rfc-editor.org/info/rfc1700>.
[RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol
(LISP) Data-Plane Confidentiality", RFC 8061,
DOI 10.17487/RFC8061, February 2017,
<https://www.rfc-editor.org/info/rfc8061>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
10.2. Informative References
[I-D.farinacci-lisp-ecdsa-auth]
Farinacci, D. and E. Nordmark, "LISP Control-Plane ECDSA
Authentication and Authorization", draft-farinacci-lisp-
ecdsa-auth-03 (work in progress), September 2018.
[I-D.farinacci-lisp-mobile-network]
Farinacci, D., Pillay-Esnault, P., and U. Chunduri, "LISP
for the Mobile Network", draft-farinacci-lisp-mobile-
network-14 (work in progress), March 2022.
[I-D.farinacci-lisp-telemetry]
Farinacci, D., Ouissal, S., and E. Nordmark, "LISP Data-
Plane Telemetry", draft-farinacci-lisp-telemetry-07 (work
in progress), November 2021.
[I-D.haindl-lisp-gb-atn]
Haindl, B., Lindner, M., Moreno, V., Comeras, M. P.,
Maino, F., and B. Venkatachalapathy, "Ground-Based LISP
for the Aeronautical Telecommunications Network", draft-
haindl-lisp-gb-atn-07 (work in progress), March 2022.
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[I-D.ietf-lisp-eid-anonymity]
Farinacci, D., Pillay-Esnault, P., and W. Haddad, "LISP
EID Anonymity", draft-ietf-lisp-eid-anonymity-12 (work in
progress), March 2022.
[I-D.ietf-lisp-eid-mobility]
Comeras, M. P., Ashtaputre, V., Maino, F., Moreno, V., and
D. Farinacci, "LISP L2/L3 EID Mobility Using a Unified
Control Plane", draft-ietf-lisp-eid-mobility-09 (work in
progress), January 2022.
[I-D.ietf-lisp-te]
Farinacci, D., Kowal, M., and P. Lahiri, "LISP Traffic
Engineering Use-Cases", draft-ietf-lisp-te-10 (work in
progress), March 2022.
[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", draft-lhan-problems-
requirements-satellite-net-02 (work in progress), February
2022.
[I-D.lhan-satellite-instructive-routing]
Han, L., Retana, A., and R. Li, "Semantic Address Based
Instructive Routing for Satellite Network", draft-lhan-
satellite-instructive-routing-00 (work in progress), March
2022.
[I-D.lhan-satellite-semantic-addressing]
Han, L., Li, R., Retana, A., Chen, M., and N. Wang,
"Satellite Semantic Addressing for Satellite
Constellation", draft-lhan-satellite-semantic-
addressing-01 (work in progress), March 2022.
Appendix A. Acknowledgments
The authors would like to thank the LISP working group for their
review of this specification. A special thank you goes to Lin Han
for email discussions on this topic.
Appendix B. Document Change Log
B.1. Changes to draft-farinacci-lisp-satellite-network-00
o Initial posting April 2022.
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Authors' Addresses
Dino Farinacci
lispers.net
San Jose, CA
USA
Email: farinacci@gmail.com
Victor Moreno
Independent
Mountain View, CA
USA
Email: victor@magooit.com
Padma Pillay-Esnault
Independent
Santa Clara, CA
USA
Email: padma.ietf@gmail.com
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