After Microsoft officially released Windows XP, people's most intuitive feeling is that their operating interface style has changed significantly, and when we open Windows XP's Huashang, explore its new application. In the meantime, we will find that in addition to providing extensive support for multimedia, Windows XP has also made significant improvements in the network function. ---- In the "Network Connection" item of the "Control Panel", the connection type is generally divided into two types: "LAN or high-speed Internet connection" and "dial-up connection". If a network card is installed on your computer, an icon called "Local Area Connection" will appear in the "LAN or High Speed Internet Connection" item, and several connection icons will be displayed on your computer with several network cards installed. Select a connection icon, click on the shortcut menu, you will find a "bridge" option in the menu, which has never appeared in the previous version of Windows, what role does it have? ---- This article will answer your questions about the specific implementation of the "Bridge" function. The operating system I use is Windows XP Professional. The installed network card includes two 3Com 3C905C, one 1394 network adapter and two Cisco Aironet wireless network cards. First, the operation guide ---- 1. Create a bridge ---- "Bridge", as the name suggests, is a bridge to achieve the connection. The bridge works on the second layer of the OSI reference model (ie, the data link layer), which only focuses on the MAC address and does not care about the transport protocol. The bridge works based on the site or Mac address, dividing the network traffic into segments and filtering it. The bridges that can be bridged include Ethernet adapters such as 10/100 Mbps Ethernet cards, the latest 1394 network adapters, and wireless network adapters. The specific steps to implement the "Bridge" function are as follows. ---- (1) Open the "Network Connection" item in the "Control Panel". ---- (2) In the "LAN or High Speed Internet" project, select each private network connection that you want to use as part of the bridge. ---- (3) Right-click on one of the highlighted private network connections and click the "Bridge" option (shown in Figure 1). After a period of connection, a new bridge is created (as shown in Figure 2). If you are not very clear about the concept of a bridge, consider it as a switch with only 2 ports. It is particularly noteworthy that the bridge itself can also be configured with an IP address, but this IP address has nothing to do with the bridging role, even if it is not in the same subnet as the two connected LANs, the two LANs can communicate. 2. Add a connection to or remove a connection from the bridge ---- (1) Open the Network Connections item in the Control Panel. ---- (2) Select the "Properties" option in the shortcut menu of the "Bridge" project, and the "Network Bridge Properties" dialog box will pop up (as shown in Figure 3). (3) In the Adapters item of the General tab, select the check box for each adapter you want to add to the bridge and click the OK button. The operation of deleting a connection from a bridge is the reverse of the above process, and will not be described here. However, you need to pay attention to the following points when doing this. ---- (1) Only one bridge can be created on a single computer, but the bridge can accommodate a myriad of network connections. ---- (2) Bridges cannot be created on computers running Windows 2000 or earlier Windows operating systems. ---- (3) If the adapter is removed from the bridge and there are less than 2 adapters reserved, the bridge will not perform the intended function, but will continue to use system resources. Second, the typical application ---- 1. Bridging ---- The most basic application of bridging is of course to connect two LANs. In the network shown in FIG. 4, two local area networks are included, which all adopt a hub-centric star topology and are connected to each other through a bridge computer with dual network cards. When the No. 1 machine attempts to communicate with the No. 2 machine, the data packet will be forwarded by the hub to all ports in the form of a broadcast. However, after receiving the data packet, the bridge computer finds that the No. 1 machine and the No. 2 machine are in the local area network 1 by querying the address list of the user, so the bridge does not broadcast the data packet of communication between the No. 1 machine and the No. 2 machine to the network bridge. Among the LAN 2. The bridge computer implements traffic isolation and segmentation of collision domains by means of address filtering. The basic bridging function can be derived from many changes depending on the actual environment in a specific application. For example, if a computer is far away from the hub (more than 100m required by Ethernet), you can use a computer that is closer to it to establish a bridge to act as a repeater and to put the free computer into the LAN. ---- 2. Three-machine interconnection ---- Many friends encounter the need to interconnect 3 to 4 computers in actual operation. The usual solution is to purchase a small hub to connect to the network. In fact, in the case of a small number of computers that need to be connected, each computer can be connected as a bridge through a computer with a dual network card. In the past, this solution was implemented by configuring a computer with a dual network card as a routing computer. This actually utilized the switching function of the router. It is well known that the packet switching of a router is fundamentally different from the switching function of a switch. Packets passing through the router are disassembled and repackaged each time, so there is a gap between the switching efficiency of the router and the pure store-and-forward switching efficiency of the switch. In addition, through this method, it is also necessary to configure a more complicated system routing, which is not an ideal solution. ---- In Windows XP, this problem becomes very simple. Users only need to create a bridge with a dual-NIC computer to create a bridge, which is very convenient. The specific operation method is as shown above. ---- 3. Building a wireless network access point (AcessPoint) ---- With the bridge function of Windows XP, we can implement the function of the wireless network access point by using a wireless network card plus a common Ethernet card (as shown in Figure 5). In the bridge computer, a wireless network connection working in the Ad-Hoc mode is connected to the Ethernet to form a bridge, so that the wireless network terminal working in the Ad-Hoc mode can access the wired Ethernet through the bridge computer. It is. If you have ever opened a wireless network access point or bridge device, you will find that they are plugging a wireless network card into a board with an integrated Ethernet card, and then bundling the wireless network card and Ethernet card with the same IP. The address is much the same as the work we did above. 4. Link Redundancy ---- For servers with high reliability requirements for communication links, in addition to dual-system backup, most of them use dual-link redundancy with switches. A redundant dual link is used between the server and the switch. One link does not work normally. The backup link is enabled only when the primary link is disconnected due to a fault. This design is based on a dual NIC system on the server, traditionally implemented using a server-specific NIC. But in Windows XP, we can achieve dual-link redundancy through the bridge function. The traditional dual-NIC solution is essentially a clustering technology application. Each of the two network cards has a chip for mutual coordination. When the driver knows that the high priority network card is enabled, the backup network card is automatically disabled. The dual-link redundancy implemented by the bridge computer is to use the bridge computer as a switch, and then enable the spanning tree algorithm to establish a loop-free forwarding topology. This ensures that the forwarding topology is acyclic, thus avoiding the occurrence of forwarding storms.