About WLAN, I believe we already no stranger to it. Almost every day we can experience the efficient and convenient WLAN brings to our lives. At home, through a wireless router, we do not have upright sitting beside the computer, you can sit on the sofa, in bed, or even sitting on the toilet mail, online Europe *** appreciate and enjoy Wireless freedom bring freedom. In the waiting room, people holding notebooks and Pad are gradually replaced by people holding newspapers and magazines. Walked into the coffee shop, the first thing that more and more people are not ordering, but ask for a password cafe Wi-Fi .......
With WLAN menacing, more and more people want to know the WLAN technology, WLAN has become one of the current hot topic. Small series Fucai, and we are willing to learn to explore WLAN technology to solve some of the problems WLAN area. Below please a cup of tea, patiently reading the following passage, we began to know and do not know the WLAN journey.
Why is the WLAN know and do not know it? One reason is that many people are already familiar with WLAN, WLAN know, but let's say we complete the definition of WLAN, but few people can say that. WLAN stands for Wireless Local Area Network, Chinese meaning is wireless local area network, WLAN definition has both broad and narrow: Broadly speaking WLAN based on a variety of radio waves (such as laser, infrared, etc.) instead of wired LAN in a wireless channel part or all of a transmission medium constituting the network. WLAN narrow definition is based on IEEE 802.11 family of standards, using a high frequency radio frequency (e.g., 2.4GHz or 5GHz band radio waves) as a wireless LAN transmission medium.
Here, we wish our daily lives WLAN in touch, we often hear "802.11n, 2.4G, 5G" is not the kind of feeling and countless WLAN narrow definition of the relationship ah? In fact, our daily lives WLAN, is the narrow definition refers to the WLAN. In the process of evolution and development of WLAN, its implementation has a lot of technical standards, such as Bluetooth, 802.11 series, HyperLAN2 and so on. The 802.11 family of standards due to its implementation technology is relatively simple, reliable communication, to achieve high flexibility and relatively low cost and so on, has become the mainstream WLAN technology standard, and the 802.11 family of standards has also become synonymous with WLAN technology standard.
About 802.11 series of standards we will detail later, but here we first understand the definition of the WLAN.
After understanding the definition of WLAN, Xiao Bian want to ask you a less able to question, we have to use WLAN at home and in the waiting room and other large establishments using WLAN experience it. We have not found that the two parts of the WLAN What is the difference ah? Have you ever thought of such a problem: the family house area is relatively small, and a large waiting room area, as if, like the family, the waiting room is also using a wireless router for home use, how to cover so much waiting room area. Less access to the user's home is generally not more than a few dozen, and in the waiting room may be hundreds or thousands of users in the use WLAN, waiting room how to meet so many users access it.
Some would say that is not in the waiting room laying a lot of the wireless router to achieve the waiting room of a wide range of coverage and multi-user access to it? However, if laying a lot of wireless routers in the waiting room, when we move back and forth in the huge waiting room is not to interrupt the signal to remind you access to the emergence of new wireless router, like moving from their homes to the neighbor, even the neighbor's wireless network with the same name and password of their own home, there will be a network outage IP address and obtain phenomenon. Interested shoes can go home and neighbors try ^ _ ^.
So what is causing some only use WLAN to meet family and other small places, while others meet the WLAN was in the waiting room and other large establishments to use it. Xiao Bian gave you about the basic framework of WLAN, WLAN everyone understand the basic architecture, the above problem is solved.
There are two basic WLAN architecture, one is FAT AP architecture, also known as autonomous network architecture. One is AC FIT AP architecture, also known as centralized network architecture. We start with the most familiar home wireless router to start, home wireless router uses a FAT AP architecture, namely autonomous network architecture. FAT AP English name is FAT Access Point, Chinese called fat access points, there are a lot of people directly called fat AP. FAT AP may transmit only a radio frequency signal for providing wireless access to the wireless terminal, but also to independently secure encryption, user authentication and user management executive functions. Think about our home wireless router, we can set a password for WLAN, you can configure a blacklist or whitelist user access control, can also manage user access (such as setting user access speed), these are in line with FAT AP Characteristics. Therefore, the wireless router for home use is a kind of FAT AP. FIG Network The following is a simple application of FAT AP-based network architecture.
FAT AP powerful, independent, have the ability to self-government, so people also known as FAT AP architecture autonomous network architecture. Does not require the intervention of specialized control apparatus, the user alone can complete wireless access, and the encrypted service data message forwarding function of service data.
Autonomy is a FAT AP independent features, but also the shortcomings of FAT AP. When a single deployment, have better since FAT AP independent, does not require the deployment of additional control equipment, it is easy to deploy, costs are low, such as in a class family or a small enterprise WLAN using a WLAN scenario, often FAT AP the most suitable choice. Tell us feel the most profound is that we use a wireless router at home will be able to enjoy the convenience of WLAN brings us. However, in large usage scenarios, such as the waiting room we mentioned above, FAT AP independent autonomy becomes its own shortcomings. Due to the large WLAN coverage area, access to more users need to deploy many FAT AP devices, and each FAT AP is autonomous and independent of, the lack of unified management and control equipment, manage them becomes very troublesome. If nothing else, these light FAT AP liters a level is a disaster. Therefore, in the case of mass deployment, FAT AP will bring tremendous management and maintenance costs. And because independent control user access, FAT AP can not solve the problem of the roaming user. In general large-scale usage scenarios in which people often do not choose FAT AP architecture, but we talk about the use of the following AC FIT AP architecture.
If you do not understand roaming, you can imagine the phone we use every day, when sitting on the high-speed rail to move from one city to another city, the cell phone signal to stop off along the way in the old network, access to the new network. Under Or imagine, we took the Pad and other wireless terminal, move from their homes to the neighbor and the neighbor's WLAN access, this process can be understood as roaming. WLAN behind introducing the various features of what will be mentioned when roaming, first understand the concept of roaming about.
Since there are fat AP, that there should be a corresponding thin AP. FIT AP English name is FIT Access Point, Chinese called thin access points, there are a lot of people directly called thin AP. Fat and different AP, in addition to thin AP provides wireless Radio Frequency signals, have substantially no executive functions. It is also because of this, it is called thin AP, while the upper comprises an AP executive functions is called the fat AP. To achieve the WLAN functionality, in addition to the FIT AP, also you need to have the management device --AC control function. AC English name is Access Controller, Chinese called wireless access controller. The main function of the AC is in all FIT AP WLAN management and control, it does not have a radio frequency AC (AC only management control device, not emit radio frequency signals), which fit together to complete the FIT AP and WLAN. This architecture is called the AC FIT AP architecture. Network diagram for WLAN AC FIT AP architecture to deploy next picture shows a large Enterprise.
We can see from the figure, depending on the AC control area and throughput, AC may be present in the aggregation layer may also be present in the core layer. FIT AP and the access layer and is often deployed enterprise branch. This level of collaboration distinct division of labor, better reflect the characteristics of centralized control of AC FIT AP architecture, this architecture has been commonly known as the centralized network architecture.
Use AC FIT AP architecture is such a large place like the waiting room to deploy WLAN, more economical than using FAT AP architecture and efficient. In AC FIT AP architecture, can be configured to send unified under the FIT AP, a unified software upgrade for the FIT AP, also can control the number of working hours in accordance with the FIT AP, etc., which greatly reduces the cost of WLAN management and control and maintenance. Moreover, since the user access authentication can solve the problem of roaming users AC unified management becomes very easy. In summary, AC FIT AP architecture is suitable for use in large-scale scenes, and FAT AP architecture for small usage scenarios.
Wireless router ordinary household use is FAT AP architecture
Large establishments generally use AC FIT AP architecture
At this point, we first phase is nearing completion WLAN technology topics. In this issue more basic, and we just talked WLAN definitions and basic architecture of the WLAN. Content simple and easier to understand, if there are any questions please reply to discuss Kazakhstan.
The current issue:
You can not say for example WLAN encountered in daily life is what architecture to use it?
