Vswitch basic knowledge Summary-exchange management

Switch Switching Mode

ExchangeMachineYou can exchange data in the following three ways:

1) pass-through:

A straight-through Ethernet switch can be understood as a line matrix telephone switch that is crossly And crossly between ports. When a packet is detected on the input port, it checks the packet header, obtains the destination address of the packet, and starts the internal dynamic search table to convert it to the corresponding output port, connect data packets at the intersection of input and output to the corresponding port to implement the switching function. Because it does not need to be stored, the latency is very small and the exchange is very fast, which is its advantage. Its disadvantage is that because the data packet content is not saved by the Ethernet switch, you cannot check whether the transmitted data packet is incorrect and the error detection capability cannot be provided. Because there is no cache, the input/output ports with different rates cannot be directly connected, and packet loss is easy.

2) Storage forwarding:

Storage Forwarding is the most widely used method in the computer network field. It stores the data packets on the input port first, and then performs CRC cyclic verification) checks to obtain the destination address of the data packet after processing the error packet, convert a search table to an output port to send packets. Because of this, the storage and forwarding method is insufficient when the data processing latency is large, but it can detect errors of data packets entering the switch, effectively improving network performance. In particular, it supports switching between ports at different speeds to ensure collaboration between high-speed ports and low-speed ports.

3) fragment isolation:

This is a solution between the first two. It checks whether the length of the packet is 64 bytes. If it is smaller than 64 bytes, it indicates a false packet, the packet is discarded; if it is larger than 64 bytes, the packet is sent. This method does not provide data verification. It processes data faster than the storage and forwarding method, but is slower than the pass-through method.

Vswitch Management Mode

Network Management SwitchYou can manage through the following channels: Through the RS-232 serial port or parallel port) management, through the Web browser management and through the network management software management.

Serial Port Management

A serial port cable is attached to a network management switch for management. First, insert one end of the serial port cable into the serial port on the back of the switch, and the other end into the serial port of the general computer. Connect the vswitch to the computer. "Super Terminal" programs are provided in Windows 98 and Windows 2000. Open "Super Terminal". After setting the connection parameters, you can use the serial port cable to interact with the switch, as shown in figure 1. This method does not occupy the bandwidth of the switch, so it is called "Out-of-band management" Out of band ).

In this mode, the switch provides a menu-driven console interface or command line interface. You can use the "Tab" key or the arrow key to move the menu and sub-menu, press the Enter key to execute the corresponding command, or use a dedicated switch to manage the switch. The command sets of vswitches of different brands are different. Even vswitches of the same brand have different commands. It is more convenient to use menu commands.

Web Management

A network management switch can be managed through a Web browser, but an IP address must be specified for the switch. This IP address is not used unless used by the Management Switch. By default, a vswitch does not have an IP address. You must specify an IP address through the serial port or other methods before you can enable this management mode.

When you use a Web browser to manage a vswitch, The vswitch is equivalent to a Web server, but the webpage is not stored in the hard disk, but in the nvram of the vswitch. You can upgrade the Web program in NVRAM through a program. When the Administrator enters the IP address of the switch in the browser, the switch will pass the webpage to the computer just like a server. At this time, it will give you the feeling that you are visiting a website, as shown in 2. This method occupies the bandwidth of the switch, so it is called "In-band management" In band ).

If you want to manage a vswitch, you only need to click the corresponding function on the webpage and change the vswitch parameters in the text box or drop-down list. Web management can be implemented on the LAN, so remote management can be implemented.

Manage through network management software

Network Management switches comply with the Simple Network Management Protocol (SNMP). The SNMP protocol is a complete set of network device management specifications that comply with international standards. All devices that follow the SNMP protocol can be managed through the network management software. You only need to install an SNMP network management software on a network management workstation. Through the LAN, you can easily manage vswitches, routers, and servers on the network. As shown in Interface 3 of SNMP network management software, it is also an in-band management mode.

You can manage network management switches in the preceding three ways. Which method is used?

When a vswitch is initially set, it usually needs out-of-band management. After an IP address is set, you can use the in-band management mode. In-band management because the management data is transmitted through the public LAN, remote management can be implemented, but the security is not strong. Out-of-band management is implemented through serial communication, and data is transmitted only between switches and Management machines. Therefore, it is highly secure. However, due to the limitation of the length of the serial port cable, remote management cannot be implemented. So which method you use depends on your security and manageability requirements.