Mar

Fun WLAN switch quickly teach you to achieve a network program

WLAN switches can be wired connection (through a switch port) to connect to the WLAN access point (AP). They also through their other WLAN switch port to connect to the corporate network. These switches are connected to the corporate wired network gateways - all from the WLAN client data frame must be sent through the WLAN switch to the corporate network.

To understand the function and its WLAN switches in the network application, you first need to understand the network architecture and WLAN access point functionality. We can control the device as a WLAN switch, the AP as a wireless terminal. This article WLAN through a detailed analysis of network architecture and the AP, the controller function, to clarify the role of WLAN switches and controllers. This article also describes the interface between the controller to the AP the different functions. , This article describes a centralized architecture with the second / three variables related to the movement and eventually will be pointed out that some of these common errors architecture views and the actual situation. In this paper, wireless terminals (WTP) the term to refer to AP, with the access controller (AC) the term to refer to WLAN control functions (whether deployed in the WLAN switch or a separate controller).

WLAN network the main framework

Common WLAN network architecture there are three:

1. Autonomy architecture

2. Centralized architecture

3. Distributed Architecture ” / P> The following sections will be in-depth description of these three kinds of architecture.

Self-Government architecture

In the autonomous architecture, WTP full deployment and termination 802.11. Therefore, the data on the wired LAN are all 802.3 frames. Each WTP on the network can be used as a separate network entity to conduct an independent management. This network access points are usually referred to as fat AP.

In the early days of WLAN deployments, most of the AP are autonomous AP, can be used as an independent entity to manage the network. In the past few years, the use of AC and the WTP a centralized architecture (see below) began to receive more and more widespread concern. The main advantage of centralized architecture is that the enterprises in the number of WTP, it provides network administrators with a structured, hierarchical control model.

centralized architecture

centralized architecture is a hierarchical framework, including the one responsible for configuration, control and manage multiple WTP of the WLAN controller. WLAN controller, also known as Access Controller (AC). 802.11 functionality is provided by WTP and the AC shared commitment. Compared with the autonomy of architecture, this model features the WTP weakened, so they are also known as the thin AP. AP on the part of the function is variable, see the following introduction.

Distributed Architecture

in a distributed architecture, the WTP of different wired or wireless connection, with other WTP to build distributed network. WTP composed of a mesh is a typical example of this architecture. Mesh in the WTP with 802.11 link, or wired link connected to 802.3. This architecture is usually used in the network of cities and other needs of outdoor components deployed. Distributed architecture does not belong to the scope of this article.

WTP function - fat, thin, and moderate AP

To understand the autonomous and centralized architecture, first of all need to analyze the functions performed by AP. We first started talking about AP from the fat, which constitutes the core of an autonomous architecture. After that we will introduce the thin AP, which is based on a centralized WLAN switch or controller, an important part of architecture. This paper will then introduce a new component called moderate AP function. It is a centralized architecture specifically optimized for the AP.

fat access point

AP is a network node can be addressed in its interface with its own IP address. Can between wired and wireless interfaces to forward traffic. It can have multiple wired interfaces, at different forwarding traffic between the wired interface - similar to a second tier or third tier switch. And enterprise wired network connection through a second tier or third tier networks. A point worth noting is that fat AP will not be returned through the tunnel traffic to other devices. This feature is very important, this paper will also introduce other AP type mentioned this point. In addition, the fat AP router can provide similar features, such as Dynamic Host Configuration Protocol (DHCP) server functionality.

AP management is through a protocol (such as Simple Network Management Protocol [SNMP], or for Web management, Hypertext Transfer Protocol [HTTP]), and a command-line interfaces. In order to manage multiple AP, the network administrator must manage one of the mechanisms through which to connect each AP. For each AP in the network topology map is shown as a separate node. Any for the management, control node cluster network management system must be (NMS) level of completion, which include the development of an NMS application.

Fat AP also enhanced a variety of functions, such as allowing specific WLAN client traffic filtering access control lists (ACL). Of these devices is another important function is associated with quality of service (QoS) features related to the configuration and implementation. For example, traffic from a specific mobile base stations may require priority over other traffic. Or, you may need to come from the mobile base station traffic into and implementation of the IEEE802.1p priority, or Differentiated Services Code Point (DSCP). All in all, because these AP can provide a lot of WLAN switch or router function, to some extent they can act as a WLAN switch or router.

This lack of AP is the complexity. Fat AP is usually based on a powerful hardware based on the need for complicated software. As it is more complicated, the equipment installation and maintenance costs are high. Nevertheless, these devices in a small network can also play a role. Some fat in the back-end for the AP control and management functions using a controller. These controllers will form a fat AP slightly simplified version - the so-called moderate AP, below, will be presented in detail.

thin access point

As the name suggests, thin AP's purpose is to reduce the complexity of AP. To simplify them as an important reason is that the location of AP. Many companies are on the AP adopted the way of high-density installation (because the distribution is difficult to access in some areas) in order to provide the best for each base station RF link. In the warehouse and other special circumstances, this phenomenon was more pronounced. For these reasons, network managers want to install only one AP, without the need for the maintenance of their complex. Thin AP also commonly known as smart antennas, and their main function is to receive and send radio traffic. They will be wireless data frame back to the one controller, and then processing the data frames, and then switching to the wired WLAN.

This AP uses a (usually encrypted) tunnel to the wireless traffic back to the controller. Not even the most basic thin AP to WLAN encryption, such as Wired Equivalent Privacy (WEP) or WiFi Protected Access (WPA/WPA2). This encryption by a controller to complete - AP is only responsible to send or receive encrypted wireless data frame, thereby maintaining the simplicity of AP to avoid upgrade their hardware or software necessary.

WPA2 makes the controller of the available encryption has become a very urgent task. While the WPA and WEP in hardware is compatible, only require a firmware upgrade, but it is not backward compatible with WPA2. Network managers do not need to replace the entire enterprise of the AP, but only to the wireless traffic is sent to the controller capable of WPA2 decryption, followed by the data frame will be sent to the wired LAN.

In the AP and the controller and data flow between the transmission control protocol is proprietary. Also, can not be in the second / three-tier, the AP as a single entity to be managed - it can be managed through the controller, but NMS through HTTP, SNMP, or CLI / Telnet to communicate with the controller. A controller can manage and control the number of AP, which means that control should be based on powerful hardware, and often able to perform switching and routing capabilities. Another important requirement is, AP and the connection between the AC and tunnels between the two entities should ensure that the packet delay to maintain at a very low level.

For the thin AP in terms of, QoS enforcement and ACL-based filtering are handled by the controller - this will not cause problems, because all of the data frame from the AP in any case have to be controlled by the transmission device. ACL and QoS functionality of centralized control is not uncommon - the use of fat AP's network also adopted this approach. This installation will be managed from the AP to the controller as a wired network traffic gateway. However, the thin AP controller function has adopted a new way, especially in the data plane and forwarding functions. Controller functionality is integrated into the connecting wireless and wired LAN into the Ethernet switch - which spawned a series of devices known as the WLAN switch. In this case, the wireless MAC architecture is referred to as the remote MAC architecture. 802.11MAC feature set are transferred to the WLAN controller, including MAC delay-sensitive functions.