Consideration for IP-Based Satellite Routing Protocol
draft-wang-rtgwg-sat-routing-protocol-consider-02

rtgwg                                                            J. Wang
Internet-Draft                                              China Mobile
Intended status: Informational                                   B. Feng
Expires: 3 September 2026                    Beijing Jiaotong University
                                                                P. Zhang
                                                      Beihang University
                                                            2 March 2026

         Consideration for IP-Based Satellite Routing Protocol
           draft-wang-rtgwg-sat-routing-protocol-consider-02

Abstract

   This document examines the advantages, challenges, and current
   research on IP-based satellite routing, and provides some
   considerations.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Advantages  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Standardized Basis for Global Interconnection . . . . . .   3
     3.2.  Mature Congestion Control System  . . . . . . . . . . . .   3
     3.3.  Hardware and Software Ecological Compatibility  . . . . .   4
   4.  Challenges  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  High Latency Leads to Reduced Protocol Efficiency . . . .   4
     4.2.  BER and Congestion Misclassification Problem  . . . . . .   4
     4.3.  Adaptation Challenges for Dynamic Topologies  . . . . . .   4
     4.4.  Challenges in Energy Consumption Management Due to Dynamic
           Changes in Network Topology . . . . . . . . . . . . . . .   5
   5.  Current Research  . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  IS-IS and OSPF Extensions . . . . . . . . . . . . . . . .   5
     5.2.  LISP for Satellite Networks . . . . . . . . . . . . . . .   5
     5.3.  New Network Header for DR-SDSN  . . . . . . . . . . . . .   5
   6.  Consideration . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Support Dynamic Routing . . . . . . . . . . . . . . . . .   6
     6.2.  Support Quality of Service (QoS) Guarantee  . . . . . . .   6
     6.3.  Support Heterogeneous Network Interconnectioncation . . .   6
   7.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   10. Informative References  . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   With the continuous evolution of the network, satellite network has
   gradually become a research hotspot.  There were three use cases had
   been defined in the TVR's use case document [I-D.ietf-tvr-use-cases].
   One of them is dynamic reachability; some examples of this use case
   are mobile satellites, predictable moving vessels and so on.

   Satellite network and terrestrial network use different physical and
   link layer protocols, making it difficult to achieve convergence at
   the bottom layer.  This problem can be solved at the network layer.
   On the one hand, TCP/IP is a simple and open protocol, which can help
   break the boundaries between heterogeneous networks to realize global
   interconnection.  On the other hand, the business is basically based
   on IP, and the development of IP-based space network can help realize
   the business integration and collaboration between heaven and earth
   and the integration and sharing of network resources, thus reducing
   the cost of network construction and operation and maintenance, and
   not only realizing the integration of heaven and earth in a more
   efficient way, but also better meeting the needs of personal

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   communication and information access, and improving the user
   experience.  The development of IP-based space network can not only
   realize the integration of air and sky more efficiently, but also
   better satisfy the needs of personal communication and information
   acquisition, and improve the user experience and satisfaction.

   Although the TCP/IP protocol architecture is very mature for
   terrestrial networks, there are still many challenges in applying it
   to the satellite network.

   This document makes some considerations on using IP for the satellite
   routing.

2.  Conventions

   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
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Advantages

   Considering advantages on IP-based satellite routing.

3.1.  Standardized Basis for Global Interconnection

   TCP/IP, as the common protocol stack of the Internet, naturally
   supports the seamless interconnection of satellite networks and
   terrestrial IP networks.  For example, Starlink realizes the
   integration of satellite link and terrestrial backbone network
   through TCP/IP protocol, and user terminals can directly use standard
   IP addresses to access Internet services.  This standardization
   lowers the technical threshold for the integration of heaven and
   earth networks, making satellite communications an effective
   supplement to terrestrial networks, which is especially valuable in
   remote areas or emergency communication scenarios.

3.2.  Mature Congestion Control System

   Mechanisms such as slow start and congestion avoidance of the TCP
   protocol provide basic congestion management capabilities for
   satellite networks.  Although the high latency of satellite links can
   diminish their effectiveness, the speed of response to bandwidth
   changes can be optimized through improved algorithms such as TCP
   Westwood.  For example, in LEO satellite networks, TCP CUBIC can
   maintain high link utilization during bandwidth fluctuations by
   dynamically adjusting the window growth rate.

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3.3.  Hardware and Software Ecological Compatibility

   Satellite communication equipment can directly reuse mature
   technologies of terrestrial networks, such as IP-based routers and
   switches.  This not only reduces R&D costs, but also facilitates the
   introduction of emerging technologies such as edge computing and
   network function virtualization (NFV).  For example, on-board nodes
   can deploy intelligent routing functions to optimize transmission
   efficiency by adjusting TCP parameters in real time.

4.  Challenges

   Considering challenges on IP-based satellite routing.

4.1.  High Latency Leads to Reduced Protocol Efficiency

   The round-trip latency of geosynchronous orbit (GEO) satellites is
   about 560ms, while low orbit (LEO) satellites reduce the latency to
   30-80ms, but it is still much higher than the terrestrial network.
   the acknowledgement mechanism of the TCP protocol significantly
   reduces the throughput in this environment, for example, the
   efficiency of the TCP basic mode transmission may be less than 25% in
   GEO satellites.  In addition, delay jitter (e.g., an average of 6.7ms
   RTT fluctuation in Starlink) further interferes with the
   stabilization of the congestion window.

4.2.  BER and Congestion Misclassification Problem

   Satellite channel BERs (Bit Error Rate) are typically 10-⁶-10-⁷, much
   higher than terrestrial wired networks.The TCP protocol can mistake
   packet loss due to random BERs for congestion, triggering unwanted
   window shrinkage.  For example, during inclement weather, such as
   rain failure, the BER of a satellite link can spike, causing TCP
   throughput to drop by more than 50 percent.

4.3.  Adaptation Challenges for Dynamic Topologies

   Satellite network topology changes periodically due to orbital
   motion, with LEO satellites switching service satellites every 15
   seconds or so, resulting in link interruptions or sudden changes in
   bandwidth.  Traditional TCP/IP routing protocols (e.g., OSPF) can
   hardly adapt to such changes quickly, which may cause path
   oscillation or data loss.  In addition, the establishment and
   disruption of inter-satellite links can lead to network segmentation,
   which increases the complexity of route recalculation.

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4.4.  Challenges in Energy Consumption Management Due to Dynamic Changes
      in Network Topology

   In satellite networks, the movement of satellites causes dynamic
   changes in the network topology.  This necessitates frequent routing
   calculations and updates by routing protocols to adapt to these
   changes.  For instance, in low-Earth orbit satellite networks, the
   rapid movement of satellites may lead to frequent updates of routing
   tables.  Each update consumes energy, including onboard processing
   power and communication energy, thereby increasing the complexity of
   overall energy management.

5.  Current Research

   Research status on IP-based satellite routing.

5.1.  IS-IS and OSPF Extensions

   The IGP extensions for predictable and scheduled changes of TVR has
   been defined in [I-D.zw-lsr-tvr-extensions].  This document defines
   the a set of extensions to IS-IS, OSPFv2 and OSPFv3 for predictable
   and scheduled changes of TVR.  These extensions can be advertised by
   the node self which has predictable and scheduled changes, or by the
   node which connected or adjacenct to the node which has predictable
   and scheduled changes.

5.2.  LISP for Satellite Networks

   The document [I-D.farinacci-lisp-satellite-network] gives the
   adaptation of LISP in satellite networks.  It describes how a LISP
   overlay structure can run on top of a satellite network underlay.
   This satellite deployment use-case (described in this document)
   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.

5.3.  New Network Header for DR-SDSN

   The document [DR-SDSN] define a new 8 B network header for DR-
   SDSN(Software-defined satellite networking) to further decrease
   overheads in packet encapsulations, where 16-bit addresses are used
   instead of 32-bit IPv4 and 128- bit IPv6 addresses. the primary two
   motivations are as follows.  First, considering the limited number of
   satellites in the constellation, it is sufficient to adopt 16-bit
   Locs for node addressing, and shorter identifiers as the source and
   destination address can significantly decrease header overheads for
   encapsulations.  Then, to distinguish different consumers and

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   traffic, user priority and type of service should be indicated in the
   header so that forwarding nodes can determine the user privilege in
   resource allocation and requirement preference for flow steering.

6.  Consideration

   Considering requirements for on IP-based satellite routing.

6.1.  Support Dynamic Routing

   Networking using IP provides superior flexibility, enhanced
   scalability, and support for dynamic routing and mobile access, among
   other things.  However, the topology of satellite networks containing
   time-varying characteristics changes frequently, and traditional
   static routing techniques cannot meet the demand.  Therefore, dynamic
   routing, such as OSPF, is needed to adapt to the dynamic changes in
   network topology.  Therefore,

   o MUST provide a discovery and resolving methodology for the dynamic
   routing.

6.2.  Support Quality of Service (QoS) Guarantee

   Satellite network may need to support multiple service types, such as
   voice, video, data, etc., which have different requirements for QoS.
   Therefore, it is necessary to design effective QoS guarantee
   mechanisms, such as differential service (DiffServ), integrated
   service (IntServ), etc., to meet the needs of different services..
   Therefore,

   o MUST support Quality of Service (QoS) guarantee for the needs of
   different services.

6.3.  Support Heterogeneous Network Interconnectioncation

   Since a satellite network may be composed of several different
   heterogeneous networks, it is necessary to address the need for
   multiple heterogeneous network connections.  Therefore,

   o MUST Support heterogeneous network interconnectioncation.

7.  Conclusion

   This document makes some considerations on IP-based satellite
   routing.

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8.  Security Considerations

   TBD.

9.  IANA Considerations

   TBD.

10.  Informative References

   [I-D.ietf-tvr-use-cases]
              Birrane, E. J., Kuhn, N., Qu, Y., Taylor, R., and L.
              Zhang, "TVR (Time-Variant Routing) Use Cases", Work in
              Progress, Internet-Draft, draft-ietf-tvr-use-cases-09, 29
              February 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-tvr-use-cases-09>.

   [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>.

   [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>.

   [DR-SDSN]  Feng, B., Huang, Y., Tian, A., Wang, H., Zhou, H., Yu, S.,
              and S. Yu, "DR-SDSN: An Elastic Differentiated Routing
              Framework for SoFtware-DeFined Satellite Networks", IEEE
              Wireless Communications vol. 29, no. 6, pp. 80-86,
              December 2022.

Authors' Addresses

   Jing Wang
   China Mobile
   No.32 XuanWuMen West Street
   Beijing
   100053
   China
   Email: wangjingjc@chinamobile.com

   Bohao Feng
   Beijing Jiaotong University
   Beijing
   China
   Email: bhfeng@bjtu.edu.cn

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   Pengfei Zhang
   Beihang University
   No.37 Xueyuan Road, Haidian District
   Beijing
   100191
   China
   Email: zhangpengfei@buaa.edu.cn

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