Nanjing University Nanjing University Delay- and disruption-tolerant networking (DTN) is used in environments with long propagation delay, constrained links, intermittent connectivity, and scheduled contacts. At the edge of such systems, local IP networks may exist, such as lunar surface networks, spacecraft internal networks, and edge computing networks. End systems in these IP edge networks may continue to use conventional IP stacks and may not process DTN-specific semantics such as endpoint identifiers, Bundle lifetimes, contact schedules, or DTN storage constraints. This document describes a DTN access gateway for IP edge networks. The gateway is placed at the boundary between an IP edge network and a DTN domain. It organizes authorized IP-side data into Bundle payloads, submits those payloads to the DTN side under controlled admission, and reflects DTN-side admission constraints back to IP edge senders through bounded pre-admission state and passive back- pressure. The main focus is edge-to-edge transit mode, in which a pair of gateways connects two IP edge networks across a DTN domain. This document also discusses an optional edge-to-DTN service access extension, in which selected IP-side requests are mapped, under local rules, to service transactions in the DTN domain. This document does not define a new BP extension block, convergence- layer protocol, Bundle payload encoding, routing protocol, contact- plan exchange protocol, or mandatory gateway implementation.