The difference between the fourth layer switch and other switch

The difference

The second layer exchange to achieve Huawei Transmission rapid exchange of information between the host in LAN, the third layer switching can be said to be the perfect combination of switching androuting technology, and the fourth layer exchange technology can provide optimal allocationof network resources, to achieve application service quality of service, load balance and safety control. The four layer switching and not to replace the who, in fact, the two layer exchange now Keng Wei and the three layer exchange has been integrated into the four layer switching technology.

The second layer switch, is to complete end - to end according to the second layer data link layer of the MAC address and MAC address table data exchange. The second layer switchonly identification data frame in the MAC address, and directly according to MAC address forwarding, very easy to use ASIC chip.

Solutions of second layer switch, is a "everywhere exchange" program, although the scheme can subnet, limit the broadcast, the establishment of VLAN, but its control ability is small,lack of flexibility, can not control the flow, the lack of the routing function.

The third layer switch, is to complete the end to end IP address according to the networklayer third layer data exchange, mainly used in different VLAN subnets route. The first data asa source of information flow is the third layer exchange (routing), the switch will have an MAC address and IP address mapping table.

And the table is stored as a source of information, follow-up data flow again into the switch,the switch will be produced for the first time and save the address mapping table, directly from the second layer consists of a source address is transmitted to the destination address, not after third routing system, improve the efficiency of data packet forwarding,solving the bottleneck of VLAN sub network transmitting information between the traditionalrouter.

The fourth layer switch can not only complete end-to-end exchange, also based onapplication characteristics of port host, determine or restrict traffic exchange it. Simply put,the fourth layer switch is based on the exchange of data packet transmission layer, is a new type of LAN switch exchange needs of the user application of TCP/IP protocol in application layer.

Layer fourth switches support TCP/UDP agreement of all the fourth layer below, can be to distinguish between types of application data packets according to the TCP/UDP port number, so as to realize the application level access control and guaranteed quality of service. You can view the third layer data of Baotou source and destination addressescontent.

You can take appropriate action based on observed information, bandwidth allocation, fault diagnosis and the TCP/IP application data stream is the key function of access control. The fourth layer switch through the task distribution and load balancing network optimization, and provide detailed statistics and accounting information, so as to solve the network congestion,network management and network security problem in the application level, so that the network is intelligent and management.

The four layer switching technology.

Fourth layer OSI network reference model is the transport layer. The transport layer is responsible for end to end communication, namely coordination communication betweennetwork source and target system. In the IP protocol stack which is TCP (transmission control protocol) and UDP (User Datagram Protocol) protocol layer is.

TCP and UDP contains the port number, it can only distinguish each packet contains whatapplication protocol (such as HTTP, FTP, telnet etc.). Additional information the TCP/UDP port number can be provided for the use of the network switches, four layer switch using thisinformation to distinguish between packages in the data, which is the foundation of the fourthlayer exchange

The main function of four layer switch as follows:

1: in the traditional packet filtering router, using fourth layers of information port number to define access control list filtering rules. The four layer exchange also borrowed the concept of control list, but and software based router is not the same, the fourth layer switching is implemented in a dedicated high speed ASIC chip, thereby filtering control line speed.

2 quality of service: TCP/UDP fourth layer information can also be used to build application communication priority. The fourth layer exchange allowed to use based on the port(application) to prioritize, set the priority queue, ensure that the important traffic (such as:VOIP, video) in treatment of the fastest, the high level service to emergency applicationnetwork.

3 load balancing: the fourth layer switching load balancing principle, is to exchange virtual connection in accordance with the IP address and TCP port, directly to the corresponding port to send data packets to the destination computer. The fourth layer exchange capacityswitch, can be used as a hardware load balancers, complete the server load balance.

The fourth layer switching based on hardware chip, so the performance is very excellent,especially for the network transmission speed, exchange is much faster than ordinary packet forwarding. The fourth layer switch equipment, all cluster host layer fourth switches and external connected with Internet, external customer calling server through the fourth layer switch dynamic distribution server, realize the dynamic load balance, when a server fails, the exchange dynamics will all flow distribution to other hosts in the cluster.

4 host standby connection: provides redundant connection host standby connection portequipment, thus effectively protection system in the switch failure, this service allows you to define the main switch, the same as the virtual server definition, they have the sameconfiguration parameters.

The fourth layer switch sharing the same MAC address, backup switch receives and the main unit all the same data. Communication content which makes backup switches to monitor the main switch service. The main switch continued to inform backup switch fourthlayers of the relevant data, MAC data and its power status. The main switch failure, the backup switch will automatically take over, don't interrupt conversation or connection.

The 5 statistic and report: the query layer fourth packet, layer fourth switches can providemore detailed statistics record. Because the administrator can collect more detailed which IP address in the communication of information, and even to collect information related tocommunication according to which an application layer service communication.

When the server to support multiple services, these statistics is especially effective for load of each application investigation on the server. Statistical service increased for the use of the switch server load balancing service connection is also very useful. Contains detailed real-time reporting and record report, comprehensive report provides a full grasp of the bandwidth resources for the administrator, so that enterprises can make better business decisions.

Layer fourth switches have a common name is "Application Switch" in the industry, the more famous the following paragraph: the United States F5's BIG-IP 2400 series link application switch can be customized load balancing, traffic priority, policy based on the flow guide,source, destination and the application of exchange.

Application of switch Web Server Director Radware can be completely available, the serverswarm optimization operation security and comprehensive security, so as to ensure theapplication of network and data center range it can achieve high reliability and performance.The United States of America Foundry company ServerIronGT-C2404F application switchcan achieve global server load balancing, load balance and high performance CSHD VPN/ firewall,transparent cache, exchange, link load balance, the anti DoS attack protection server.

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