ccna 200-301 network simulator toolstation merksem

ccna 200-301 network simulator toolstation merksem.system, for example, the post offices in both locations are in the same postal subsystem; while the different agencies in the same location are not in the same subsystem.different agencies in the same place are not in the same subsystem, for example, the post office and the transportPost Office . - The relationship between them is one of serving and being served. It is quite obviousInter-postal agreementinterdepartmental convention precipitates "transportation department .....' Transport sector|Rather, the two engagements are different in that the former (the two post offices) is a departmentalThe former (the two post offices) is an intra-departmental engagement, while the latter (the post office and the transport department) is a differentA1 I-B interdepartmental conventions. In a computer network environment, two computersFigure 2-2-1 The process of communicating between two processes in the hierarchical model of a postal system is very similar to the process of postal communication.To reduce the complexity of computer network design, people often divide computer networks into a number of different functional layers by function. The communication rules between equal layers in the network are the protocols used in that layer, such as the set of communication rules about layer N, which is the protocol of layer N. The communication rules between different functional layers of the same computer are called interfaces, and the interface between layer N and layer (N+1) is called the N/(N+1) layer interface. In general, protocols are communication conventions between equivalent layers of different machines, while interfaces are communication conventions between adjacent layers of the same machine. The number of layers, the names and functions of the layers, and the protocols vary from network to network. However, in all networks, the purpose of each layer is to provide a certain service to the layer above it.Protocol hierarchy is different from the concept of modularity in programming. In programming, modules can be independent of each other, put together at will or in parallel, whereas a hierarchy must have a top and bottom, which is dependent on the flow of data. The entities that make up the equivalent layers of different computers are called peer-to-peer processes. Peer processes do not necessarily have to be the same program, but they must be identical in function and use the same protocol.