What are the main features of the bundle layer structure?

(3) Postal-style delivery service.

4) Routing.In the routing and forwarding framework provided by the DTN architecture, the DTN is defined as a multiple graph, that is, there may be multiple connected edges between nodes.To provide maximum flexibility in area design, the DTN architecture itself does not specify any particular type of routing mechanism.

(5) reliability and custody transfer.The custody transfer is a concept proposed to maintain an end-to-end connection state and to deal with high packet loss rates and resource shortages.TN faces a high message packet loss rate and needs to ensure that nodes that do not have sufficient resources do not have to undertake and maintain end-to-end reliability transmission tasks.Therefore, once the bundle of messages being held is passed to a Persistent node, the source node does not have to continue to maintain a copy of the message bundle.For example, when reliable delivery is provided by the underlying transport, the corresponding aggregation layer only needs to provide corresponding link state management.Figure l.3 Describes a typical DTN protocol stack.

(7) Time synchronization.The DTN architecture requires time synchronization between communication nodes.Flow control in the TN architecture refers to limiting the transmission rate of the DTN node to match the reception rate of the next hop node.Flow control decisions must be made within the bundle layer, although they may require support from the underlying transport layer.Congestion control refers to handling contention for persistent storage in the DTN gateway.The security requirements of the TN architecture limit access to available scarce resources, with the primary goal of preventing unauthorized applications from utilizing network resources and preventing authorized applications from accessing services that are higher than their own.Therefore, it becomes necessary to identify and discard damaged message bundles and detect damaged nodes.