Interplanetary Networking Issues

1. Interplanetary Networking Issues Chris Taylor (ESA) DTN working Group Input October 2009

2. ESA driving inputs (1) • Specification approach • DTN is being proposed as a network layer for space based on the same paradigm as the IP network layer used for terrestrial networks • IP operates in combination with an accompanying protocol stack (TCP/IP, UDP, FTP, etc) to support user applications (IP was not defined in isolation) • The selection of a network layer protocol for space must take a similar approach and also consider application requirements and the accompanying protocol stack • We cannot just assume that a network layer is a “good thing” and proceed blindly with its implementation • Operations requirements • We cannot discount the fact that operations in space have their unique requirements and that these are different to those of the typical terrestrial internet • As part of the specification process for internetworking we must take these requirements into account • Timescales • We are unaware of any near term missions that require DTN. Mars missions are locked into existing protocols and lunar missions have been delayed • We therefore have no urgent need to develop internetworking and we can take the time necessary to perform the required analysis • Thus we should complete the Green Book before embarking on Blue Book specifications

3. ESA driving inputs (2) • Evolution • We do not expect all missions to move immediately to an networked architecture, rather it should be on the basis of need and real benefit (to the missions) • We therefore need to provide an evolutionary path whereby infrastructure is able to transit to the desired end-state when required and with minimum impact • Existing protocols • We have already determined that even with fully deployed networking we will still have the requirement for file transfer in combination with Applications to support direct TM/TC • This requirement is also applicable to existing missions and is needed now • Current mission needs • From ESA’s perspective, the use of CFDP together with cross supported Applications for direct TM/TC is the key to supporting missions using a single spacecraft or 1 hop relay configuration, and is not in conflict with the later deployment of DTN when justified • We therefore propose that the definition of a CFDP/TM/TC solution combined with existing CCSDS protocols should be promoted as part of the CCSDS internetworking roadmap. Summary: ESA takes the position that in order to fulfil its goal the Green Book on internetworking must take full account of the above