IP Networking in Deep Space

This episode of PING is an interview with Marc Blanchet from Viagenie in Quebec, Canada. Marc has been active in Internet Procotols and the IETF for decades, most recently focussed on Internet Protocol communications in deep space. Marc presented at the recent APRICOT/APNIC61 meeting held in Jakarta. We've got used to the idea of IP working in Low Earth Orbit, with the rise of Starlink as a high speed service which in many cases out-performs terrestrial services available in rural and remote locations. And, we've had IP services mediated via GeoSynchronous orbit satellites like DirecTV, which are now significantly less popular because of one overriding problem: the very long end-to-end delay. People find the half-second of round-trip time to a GEO satellite unacceptable. But, in space, things get much worse. Marc's work looks at space contexts which go far beyond these orbital "shells" around earth, into the distances to the Moon, to the Asteroid belt, and beyond to other planets. The delay component in these networks isn't just an inconvenience, it has very real implications for rount-trip-time effects on a protocol like TCP, which demands a stream of "ACK" signals to manage the sender and receivers models of bandwidth and delay and retransmission. Marc has been working on how to simulate the effects of these very long delays using earth bound Virtual Hosts and code, using the Linux TUN device, and TC-NETM along with code developed by his team. This allows them to programatically define an experiment in delay, loss, re-ordering terms, which can span hours of packet-in-flight time, and look at how switches and routers, intermediate elements of an end-to-end IP exchange can work. Code patches to these systems to represent delay as a 64 bit quantity now mean it's theoretically possible to test IP out to the edge of the galaxy, if you had a way to keep machines running that long. If we look at what we actually want from IP networks in deep space, TCP isn't the right choice for how to get applications to work: There is a much better choice in QUIC, a more modern session-layer like protocol which can deploy over unreliable transport like UDP, and which integrates transport-layer security and IP address agility into the same model. As Marc discusses in this episode. IP in space is already a reality, with deployment of mobile telephony 4G base stations to the moon, and Chinese researchers experimenting with QUIC. The IETF is actively exploring the protocol options in the TIPTOP working group.