# Leveraging IPv6 and ICMPv6 for Delay-Tolerant Networking in Deep Space
###### Abstract  
Communications in delay-tolerant networking (DTN) environments like deep space face significant challenges due to immense distances and the intermittent nature of links. Overcoming these issues requires moving beyond the assumptions of immediacy and reliability that underpin traditional terrestrial Internet Protocol (IP) networks. Historically, deep-space networks have relied on custom architectures or protocols like the Bundle Protocol (BP) to address these challenges; however, such solutions impose the constraint that nodes must implement the chosen protocol for proper operation, thereby not providing interoperability with standard IP-based nodes. This paper proposes an alternative approach, leveraging innovations in IP version 6 (IPv6) and Internet Control Message Protocol version 6 (ICMPv6) to integrate delay-tolerant features directly at Layer 3. By embedding these functionalities within the existing IPv6 framework, the proposed IP-compliant solution enhances interoperability, with terrestrial networks enabling DTN nodes to seamlessly communicate with compliant IPv6 nodes. This study provides a detailed comparison of the capabilities of IPv6 and BP version 7, highlighting gaps and opportunities. Based on this analysis, a node architecture is designed to implement the necessary functionalities for DTN, paving the way for more seamless integration of deep-space and terrestrial networks while reducing complexity and improving scalability. delay-tolerant networking(DTN); IPv6; ICMPv6; Bundle Protocol (BPv7); deep-space communications [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31  
To prevent a future characterized by isolated and non-interoperable space networks, it became evident that the space communications community required a standardized, common solution for interplanetary networking [6; 7]. The first attempt to define an architecture for the future space network was made in RFC4838 [8], which introduced the concept of delay-tolerant networking (DTN), a network paradigm designed to face the challenges posed by harsh environments and conditions such as high delays and disruptions, also defining the features that a network should implement in order to counteract them. This came with the conclusion that, at the time, the traditional Internet Protocol (IP) suite did not have the capabilities to fit in this context. Consequently, the Bundle Protocol (BP) was designed, and two standardized versions have been implemented (so far): Bundle Protocol version 6 (BPv6) [9] and the more recent Bundle Protocol version 7 (BPv7) [10], offering a solution based on a store-and-forward mechanism that fundamentally works at application layer (L7) as an overlay of the underlying networks and directly below the applications. The main limit of this solution, which is also one of the motivations of this research, is that it requires source, destiny, and intermediate nodes with intermittent links to implement the BP, creating a network not interoperable with existing Internet nodes. This limited interoperability with the terrestrial Internet, in the context of scientific agencies and strictly planned space missions, was reasonable and did not represent a crucial issue. However, in the era of the New Space Paradigm, with numerous private companies now conducting space missions and new sectors other than the scientific one launching their space programs, the lack of interoperability becomes a tangible problem. It is not hard to imagine that in the foreseeable future a user might want, for example, to use their smartphone to exchange emails between the Moon and Mars. This would require the packet to travel across many different nodes, some of which are non-DTN- and some others of which are necessarily DTN-enabled. To achieve this, an IP-compliant solution that enables packets to traverse the network regardless of the nature of the nodes is essential.