* Question
| What are the main features of the bundle layer structure? |
* Answer
| reliable delivery of messages, the DTN gateway is responsible for storing messages in persistent storage.A name tuple consists of two variable-length parts in the form {region name, entity name, and.The region name is globally unique and has a rigorous topological meaning through hierarchical construction.An entity name is the name of a node in a particular area. It is unique within the area and not unique outside the area. It can be any structure.Similar to postal services, the DTN architecture takes three priorities, Bulk, Normal, and Expedited, conceptually corresponding to low, medium, and high priorities.
(4) Routing.Based on network characteristics, contacts between nodes are classified as Persistent, On.Demand, Scheduled, Predicted, and Opportunistic, of which the latter three are the most common of DTN.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.The core is that the message jumps from one DTN node to the next DTN node and implements reliable delivery.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.Assuming that the underlying layer can achieve reliable transport, you need to add a protocol stack containing a specific aggregation layer to ensure the implementation of these underlying functions.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.This requirement stems from the fact that many distributed applications in a challenging environment require time synchronization, such as message bundle identification, route scheduling, message life cycle calculations, etc., which are usually done through an external non-DTN protocol.(8) Flow control (flow contr01) and congestion control (congestion contr01).The FC standard does not specify a specific congestion control mechanism, so the congestion control mechanism is an open research issue.(9) Security.A popular security mechanism is hop-by-hop and end-to-end authentication and integrity mechanisms. The purpose is to use the data integrity of the application layer to implement access control for data forwarding and storage. |
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