RoPro Routing and management protocols for large constellations with inter-satellite links

Status date
Activity Code

The objective of the activity is to develop congestion-aware, Quality-of-Service-aware, multipath unicast and multicast routing and network management protocols for constellations with large number of satellites equipped with inter-satellite links (RF and optical). The protocols are implemented and tested in a testbed.

  • Development of space-ready hardware that supports routing on several Gigabit network interfaces
  • Design of effective load-balancing solutions for routing in Satellite Constellation Networks (SCNs)
  • Interoperability with existing terrestrial networks

Current fully operational satellite services only support so-called bent-pipe channels, that is simply receive data from ground and forward it to another (fixed) ground station. In contrast, the technology developed in this project allows routing the data in orbit between several satellites and delivering it directly to the destination. 

Several projects worldwide are aiming at deploying a satellite network that also supports in-orbit routing, with up to 300 Mbps in the final deployment stage and even with up to two Inter-Satellite-Links (ISLs) per satellite. The hardware developed in this project aims to support user data rates up to 1 Gbps and can route traffic between four ISLs, allowing faster routes than at systems with only up to two ISLs. In addition, the load-balancing and management capabilities of the routing protocols aim to ensure network operability even in the most adverse conditions.


The intended work mainly entails the development and implementation of a load-balancing routing protocol for a Low Earth Orbit (LEO) Satellite Constellation Network (SCN). The resulting scheme should find the best path in a non-uniformly congested and dynamic network with different QoS classes, while making the best use of the available capacity. To this end, a system-level software simulator, as well as a hardware demonstrator, which allow for configurable in-depth analysis, are developed. The selected routing solution is a dynamic decentralized routing scheme, based on Software Defined Networking (SDN).

System Architecture

The project entails the development of two different systems: A hardware demonstrator, that consists of the final routing hardware and a verification environment, and a system-level software simulator, capable of simulating traffic in entire Satellite Constellation Networks (SCNs). The hardware demonstrator consists of the routing hardware, which is the Device Under Test (DUT), and peripheral systems that generate the test traffic and facilitate device evaluation. The DUT implements the proposed routing and management protocols in both, control and data plane. It routes traffic between its four ISLs and two Earth-Satellite-Links (ESLs): a feeder link that connects to a gateway and one user link that aggregates traffic from all users in a satellite’s coverage area.

The simulator is a model-based, modular software simulation of entire SCNs. It can simulate varying user distributions, traffic types and classes as well as different and dynamic network topologies. Thus, it is capable of representing the entire complexity of delivering Internet connectivity via Satellite Constellation Networks (SCNs).


The project is divided into seven main work packages:

  • Output 0: Defined Reference Scenario
  • Output 1: Finalised Technical Specification
  • Output 2: Selected Technical Baseline
  • Output 3: Preliminary Design Baseline
  • Output 4: Implementation and Verification Plan
  • Output 5: Verified Deliverable Items and Compliance Statement
  • Output 6: Technology Assessment and Development Plan

The nine main project milestones are:

  • MS0: Kick-off Meeting at the beginning of the project (07/2021)
  • MS1: Review Output 0 (09/2021)
  • MS2: Review Output 1 (10/2021)
  • MS3: Review Output 2 (11/2021)
  • MS4: Review Output 3 (09/2022)
  • MS5: Review Output 4 (09/2022)
  • MS6: Review Output 5 (05/2023)
  • MS7: Review Output 6 (06/2023)
  • MS8: Final review at the end of the project (06/2023)
Current status

Output 1: Finalised Technical Specification ongoing.

Recent achievements: 

  • Output 0: Defined Reference Scenario
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