The example explains the research of WMN

WMNThere are two main methods to study networking technology. One is to carry out the research work by using the simulation method, for example, based on the NS-2 and OPNET simulation software, establish the WMN network protocol model and service transmission model, Design and Performance Analysis of the Protocol. At the same time, a smaller network structure model, business model and key technologies are abstracted Based on the WMN network structure to implement a practical experimental network, that is, the WMN test bed, tests and Performance Analysis on a WMN instance are also currently being studied by many foreign research institutions.

For example, Microsoft Research Institute has established a 802.11-basedWireless MeshNetwork lab platform, MIT established a Roofnet lab network platform to enable WMN to provide Internet access services. Among them, the Mesh network platform built by Microsoft Research Institute adds a Mesh connection layer between the network layer and the MAC layer of the node, and the DSR is modified to the routing protocol of the wireless Mesh network.

MIT builds a Roofnet network consisting of about 20 nodes. Each node is configured with an 802.11b wireless network card and an omnidirectional antenna, which works on the same channel and is based on the Linux operating system, the routing protocol adopts the Srcc protocol similar to the DSR routing protocol. The Mesh client dynamically obtains the IP address through DHCP and accesses the Internet through the gateway node. At present, IEEE 802.11 wireless transmission technology is very mature, and its products are cheap and widely used. based on IEEE 802.11 technology, WMN experimental platform is constructed, WMN networking technology is a feasible and widely used solution.

To study the WMN networking technology and node implementation scheme, a WMN testing platform is proposed. This platform provides wired and wireless access services, such as IEEE 802.11-based WLAN access, including centralized AP access and Ad hoc access, and IEEE 802.3-based wired access,.

In WMN, when the number of Mesh customer nodes is large, it can constitute an Internet subnet and access the Mesh backbone network through the Mesh router. In some regions, when the number of Mesh customer nodes is small, the access network can be considered as a network segment and connected to the Mesh backbone network through the Mesh bridge. The Mesh bridge function is similar to an Ethernet Hub or switch. Mesh bridges should be inexpensive and can effectively forward data frames between different wireless network segments. To this end, we have defined the Mesh Bridge Function and designed the implementation scheme of this device.

Mesh bridges provide access services for different access nodes, including WLAN Access, Ad hoc access, and wired access, and implement protocol conversion between different access methods. A Mesh bridge solution is to run the Redhat Fedora Core 6 Operating System 2.6.18 on an Intel x86 laptop as a software and hardware platform. The RJ45 interface provided by the laptop provides a wired network connection interface, expand a wireless network card through the PCMCIA bus to provide wireless access. The model of the wireless network adapter is DWL650. Based on the Intersil's Prism2/2.5/3 chipset, the Host AP is used as the driver. It supports the Host AP mode and provides IEEE 802.11 access functions similar to AP.

Build a minimum WMN verification system, as shown in figure 4. The Protocol Conversion Function of Mesh bridge is implemented based on Libpcap and Libnet technologies. Libpcap technology can capture data frames, while Libnet technology can send data frames. The second layer (Link Layer) forwarding technology is used to complete data forwarding between different network segments and protocol frame format conversion. Because the system uses the second-layer forwarding technology, rather than the third-layer IP forwarding technology of the Mesh router, it can speed up data forwarding between different network segments and save data forwarding time.

The system consists of two parts: Two Mesh bridges and three Mesh clients. Two communication and transmission interfaces are configured for the Mesh bridge. One is used to provide the Mesh client access service, including Ethernet access or WLAN Access. The other end is connected to the Mesh backbone network and uses the Ad hoc network's routing protocol, which serves as an exchange node in the Mesh backbone network. Mesh clients are divided into two categories: WLAN Access and Ethernet access. Because IEEE 802.11b supports 11 channels and there are 3 non-overlapping channels, the wireless access channels of Mesh bridges use Channel 1 and Channel 6 respectively, the Ad hoc connection between Mesh bridges uses Channel 11, so that each wireless channel does not interfere with each other.

In this system, data communication between any two clients can be realized. Based on this system, the second-Layer Routing Switching Algorithm can be further studied. A second-layer exchange routing algorithm (MARP) based on MAC addresses is proposed in the literature. It completes the routing request and response process through the extended Address Resolution Protocol (ARP. The next goal of this experiment system is to design and implement an effective second-layer switching algorithm to verify the algorithm performance.

WMN research experiments show that WMN is a feasible network structure for wireless access and a networking technology with broad application prospects.