Fourth floor exchange
End-to-end performance and service quality requires load balancing for all networking devices to ensure smooth flow between clients and servers. The second floor and the three-layer exchange product play a good role in solving the bandwidth and capacity issues of the LAN and the Internet, it may not be enough, but also more performance, and this is the use of four exchanges. .
Four-layer exchange technology uses information in the third layer and the fourth layer to identify application data flow session, including TCP / UDP port numbers, marking the application session starts with the "SYN / FIN" bit and IP source / destination address. Using this information, the four-layer switch can make intelligence decisions that forward session transport streams. For a variety of different systems to support a large-scale enterprise data center, an Internet service provider or content provider, and when replication functions on many servers, the role of four-layer exchange is particularly important. Four-layer switches are designed for high-speed intranet applications, which support 100Mbps or Gigabit interface.
Four-layer exchange supports other functions in addition to load balancing function, such as based on the application type and the transfer stream control function of the user ID. With multi-stage queuing techniques, the fourth layer switch can mark the transport stream according to the application and assign a priority for the transport stream. In addition, the four-layer switch is placed directly on the front of the server, which understands the application session content and user permissions, thus making it an ideal platform to prevent unauthorized access servers.
Seventh floor exchange
In terms of high availability and load balancing, there are many advanced tools that can be used to return to the seventh layer information of the end user by the application. Users can not only verify that the correct content is sent, but also open the data packet transmitted on the network (not considering the IP address or port), and make load balancing decisions according to the information in the package.
In essence, this intelligent migration beyond the function of the fourth layer. Up to devices with a fourth layer function cannot identify different types of transport streams that flow through this port, so they treat all transport streams.
However, the transport stream is not all the same. For load balancing products, it is very useful to know that data flowing through this port is very useful for streaming or a simple request for a commodity in a commodity directory, and maybe the merchant wants to give a higher priority for customers who need this directory entry. Many devices with fourth layer functions treat these two types of data in the same manner, thus may send streaming data to a server that cannot be responded, resulting in errors, and delay.
The intelligence of the seventh layer can be further controlled, that is, control of all transport streams and content. This type of partial function of the product of the seventh layer cognition is to ensure that different types of transport streams can be given different priorities. Equipment with a seventh layer cognition is not based on routing devices or applications to identify differential services (DIFF-Serv), universal open policy service, or transport streams of other service quality protocols, which can be filtered and assigned priority for transport streams and assign priority. This allows you to rely on applications or network devices to achieve these purposes. The seventh floor exchange can achieve effective data stream optimization and intelligent load balancing.
