How can I prompt "Welcome to Hubei" by SMS in Anhui?

Your location has been covered by Hubei signal.

Overlay network is simply an application layer network, which is application-oriented, and does not consider or rarely considers the problems of network layer and physical layer.

Overlay networks allow information to be routed to the destination host without IP address identification. For example, Freenet and DHT (Distributed Hash Table) can route information to a node that stores a specific file, but the IP address of this node is not known in advance. For example, P2P is a kind of overlay network. P2P is a peer-to-peer overlay network with centralized and decentralized fractal concepts. Network coverage refers to the range in which users can receive network signals.

For example, the network coverage radius is 10 meter, that is, all devices within the radius of 10 meter from the transmitting point can receive signals. Usually refers to the effective signal receiving range of wireless signal networks, such as mobile phone networks and wireless networks.

Redundancy coverage:

Redundancy coverage = number of paths included in the routing structure of application layer/number of paths included in the routing structure of IP layer.

The higher the ratio, the better the performance of application layer routing, and of course the greater the investment and overhead. The best balance point depends on the characteristics of service and network, that is to say, we must first determine the degree to which the application layer path can solve the problem, such as providing the success rate of data forwarding and recovery; Secondly, the factors that affect this index, such as failure mode.

By solving this equation, we can analyze the number and location of nodes that need to be deployed. For example, the higher the network failure rate, the more application-layer router nodes need to be deployed in order to achieve the same path elasticity.