The Internet Society’s Interplanetary Networking Special Interest Group (IPNSIG) has called for the development of “a common, interoperable, autonomous, and scalable routing framework within the Solar System Internet.”
SIG’s call was announced in its September newsletter, which described a late meeting of the panel’s Architecture and Governance Working Group, which considered current approaches to routing traffic in space and attempted to make a recommendation on realizing a common interplanetary network architecture create.
This recommendation has now been issued and outlines four principles that the group believes are necessary for a routing framework that can serve the solar system, namely:
- The overall goal is to populate forwarding tables or routing tables (where appropriate) without human intervention and deviate from the Earth-centric management scheme
- common ground
- To enable autonomy, we need a common and standardized way to:
- The filling of a forwarding and (where routes are calculated) routing table
- Feature that allows the bundle protocol agent to access a forwarding table API that answers the question: “Where should I send this bundle to and with what CLA/address?”, similar to ARP lookup interoperability
- Define a set of functions common to each node
- Cross-regional routing should be based on a common standard
- Intra-regional routing could be heterogeneous, employing methods appropriate to the needs of a specific environment or mission
- Inter- and intra-regional routing should be interoperable
- Architecture must be structured somehow (hierarchy)
- Node IDs, addressing schemes, and segmentation concepts need to be further explored to accommodate the size of the SSI
The IPNSIG has already developed a technology called Delay-Tolerant Networking (DTN) that addresses the issue of latency. DTN tries to account for the fact that in space, long distances or network nodes that disappear behind a planet create latencies and other conditions that don’t often disrupt terrestrial networks. DTN therefore adds some store-and-forward technologies so that packets are not dropped because there is no node to contact.
The SIG meeting explored additional internetworking ideas to move DTN forward, evaluating their ability to prioritize high-value data, their efficiency, and their ability to scale to 100,000 nodes.
The candidates are listed in this summary report of the August meeting. Among the schemes considered was one called “Spray & Wait,” which assumes that the nodes are unaware of the network, but where the nodes determine the optimal number of copies of data that can be transmitted. When traffic reaches a node, it’s forwarded, and eventually the network figures out how many copies are being passed around and stops routing others than those already there on road to the target node.
Spray and Wait was one of five approaches that met IPNSIG’s stated goal of scaling to 100,000 nodes, but failed to meet other criteria.
While the SIG has called for work to begin on the routing framework, it remains unclear who will do the work, select relevant engineers or decide a development process. ®