In space exploration missions, the spacecraft have limited computing resources. In particular, the communications environments for these spacecraft, whether in deep space or the cislunar region, are characterized by intermittent connectivity loss, long signal-propagation delay, and high bit-error rates between spacecraft and their ground stations. Delay-Tolerant Network (DTN) has been introduced to enable automated, efficient communication among flight-mission entities in these environments. However, most flight-mission entities are not yet equipped for DTN; a mechanism is needed whereby DTN-enabled entities and non-DTN-enabled entities can easily interoperate. The CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol (CFDP) is supported in both DTN and non-DTN communication fabrics, so perhaps CFDP file transmission can serve as the common communication medium that bridges the two. When CFDP runs without a Bundle Protocol (BP), it requires a more complex CFDP implementation, and multi-hop communication is more difficult to configure. This paper presents a tunneling mechanism that relays CFDP protocol data units (PDUs) between a non-DTN-enabled CFDP entity and a DTN-enabled CFDP entity. This enables CFDP-over-link implementations to bridge into BP networks to simplify multi-hop forwarding through the BP network. A proof-of-concept implementation of the tunneling service has been developed and tested using the Interplanetary Overlay Network (ION) DTN software to evaluate this concept of CFDP PDU relay/forward functionality to enable communication between the two heterogeneous space communication fabrics. Test setup, test results, and future work on the tunneling service are also discussed.

中文翻译：

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异构深空通信​​资产之间通过 DTN 的 CFDP PDU 隧道服务

在太空探索任务中，航天器的计算资源有限。特别是，这些航天器的通信环境，无论是在深空还是在地月区，都具有间歇性连接丢失、长信号传播延迟以及航天器与其地面站之间高误码率的特点。引入了延迟容忍网络 (DTN) 以实现这些环境中飞行任务实体之间的自动化、高效通信。然而，大多数飞行任务实体尚未配备 DTN；需要一种机制，使启用 DTN 的实体和不启用 DTN 的实体可以轻松互操作。DTN 和非 DTN 通信结构均支持 CCSDS（空间数据系统咨询委员会）文件传输协议 (CFDP)，所以也许CFDP文件传输可以作为连接两者的通用通信媒介。当 CFDP 在没有捆绑协议 (BP) 的情况下运行时，它需要更复杂的 CFDP 实现，并且多跳通信更难以配置。本文提出了一种隧道机制，可在非 DTN 启用的 CFDP 实体和 DTN 启用的 CFDP 实体之间中继 CFDP 协议数据单元 (PDU)。这使得 CFDP-over-link 实现能够桥接到 BP 网络，以简化通过 BP 网络的多跳转发。使用星际覆盖网络 (ION) DTN 软件开发并测试了隧道服务的概念验证实现，以评估 CFDP PDU 中继/转发功能的这一概念，以实现两个异构空间通信结构之间的通信。测试设置，