A, HCNA network technology study guide
In order to achieve network interoperability and a wide variety of network applications, network devices need to run a variety of protocols has been achieved wide variety of specific functions. Face various and myriad of functions, we can from the perspective of network architecture, the introduction of a layered model features: a variety of specific features of different categories, some of the functions of a similar or similar purpose and effect of the plan normalized to the same level; different functions belonging to the same level, its purpose and effect are similar or close; belong to different levels of functions, its purpose and effect of having a significant difference.
We know that the various functions of network devices through a variety of corresponding protocols running achieved. Therefore, the protocol is a layered model function corresponding to the hierarchical model; different protocols belonging to the same level, its function is similar or similar action; belong to different levels of the protocol, which has a significantly different functional roles.
Second, finishing
Function 1, hardware
A: a physical hardware device as a member, which is itself only with relevant physical properties, characteristics associated with the function. For example, a rectangular box, it has the features include: a rectangular shape, a recess formed in the internal space; according to their characteristics, we conclude that: a solid can be placed on a plane, can be appropriate containing other things.
2, the basic functions of the electronic device
A: The electronic device as a hardware device, necessarily have the basic shape characteristics and hardware function derived, on this basis, they also has a function for transmitting current.
3 advanced features, electronic equipment
A: When manufacturers of electronic equipment, will be used to control some of the current transfer rules bound to the electronic device, it has reached in the course of the use of electronic devices, to achieve the purpose of a certain function by controlling the transmission of electric current. These rules, we called them the "Agreement" [or] software.
That is, the use of electronic devices in our lives, as we realize the value of its function, is based on physical characteristics, advanced functions as the core use.
4 Conclusion
A: The advanced functions of electronic devices from the "agreement", the corresponding tiering, we can apply these protocols used to implement functions separated. The protocol has the purpose and effect similar or close to the same level of classified; agreement with a different level, its function, or a similar process is similar, belonging to different levels of the protocol, the function, effect a clear difference.
Third, the hierarchical model brings benefits
answer:
1, more easily standardized: each layer to focus on where their main function level, and will not make the problem of divergence, making it easier to develop appropriate protocols or standards.
2, lower relevance: Add a layer protocols, reduce, update or change, and will not affect other aspects of the agreement to work; protocol layers can be relatively independent of Liberty.
3, easier to learn and understand: for staff learning and research networks, the hierarchical model can make the relationship between the working mechanism of the entire network as well as numerous networking protocols more clear and lucid, easy to learn and understand.