Switching technology to the "spire"

Multilayer switching technology will drive the development of the network, as a core technology of the future network, will also provide users with a variety of applications in the future scalable solutions to lay a solid foundation.

Data exchange technology from the simple circuit switching to two-tier exchange, from two-tier exchange and gradually developed to today's more mature three-tier exchange is only a few years time.

And immediately after the third exchange, the fourth layer Exchange, the seventh layer Exchange concepts are followed, the development of exchange technology has run to the "Spire" (OSI computer network architecture is divided into seven layers). The rapid development of the computer network acceleration is surprisingly fast.

Three-tier switching allows packets to be forwarded at high speed

The two-layer switching technology is developed from the Network Bridge to VLAN (virtual local area network), which has been widely used in the construction and transformation of LAN. The second layer switching technology is the second layer in the OSI seven-layer network model, that is, the data link layer.

The disadvantage of the two-layer exchange is that the broadcast domain is too large and can not handle the data exchange between different IP subnets. This network structure is flat and has no hierarchical concept. Therefore, in order to use the advantages of two-layer forwarding efficiency, but also to deal with three-tier IP packets, three-tier switching technology was born.

The three-tier switching technology, also known as multi-layer switching or IP switching, is named after working in the third layer of the OSI seven-layer network standard Model.

The three-tier switching technology is the third layer in the network model to implement high-speed packet forwarding, as shown in the figure.

The emergence of the three-layer switching technology solves the problem of network bottleneck caused by the low speed and complexity of the traditional routers, after solving the division of the network segment in the LAN, the network segment must rely on the router for management.

Like a normal two-layer switch, the three-tier switch maintains a table of addresses (usually called a cam table) for a two-tier exchange, which corresponds to the MAC address and the outbound interface.

In this way, whenever an Ethernet data frame is received, the three-layer switch determines if the data frame is not sent to itself, then query the Cam table based on the destination MAC address of the data frame, and if it can be hit, it is usually a list of outgoing interfaces according to the result of the query. If it is not hit, the data frame is broadcast to all ports.

Three-tier exchange is more secure

At present, the three-layer switch, especially the high-end three-layer switch, has been greatly improved in routing forwarding capability, interface type, business capability, QoS and security, billing, authentication and other functions.

In the route forwarding capability, the traditional switch will be limited by the cache (cache) capacity, for example, when the network size becomes larger, the network address increased, there is the risk of cache depletion, especially the current network of viruses, fake address attacks more and more, A large number of spoofed IP addresses will soon deplete the resources of the switch.

Therefore, the high-end three-tier switch also uses a similar router's "longest matching" way, that is, does not match the full IP address, only according to the network segment for the longest match, so that it can better adapt to network size and traffic patterns change. At the same time, because of the development of ASIC technology, this "longest match" can be completed by hardware, and the three-layer switch can adapt to more complex network environment without affecting forwarding speed.

In the virus, attacks increasingly rampant today, the network security problem is more and more important, solves the security problem needs to support to the network edge to the illegal traffic filtering, to the user authentication and so on the ability.

At present, the three-layer switch basically supports the configuration of ACL policy, can filter illegal data flow according to traffic characteristics, or adopt traffic restriction strategy, which limits the spread speed and harm degree of virus or attack traffic to a large extent.

Multi-layer switch reaches top level

The rapid development of the Internet accelerates the rapid increase of information, which adds great pressure to the Network Information Center server. In the face of the network core system pressure mitigation needs, the fourth layer switch emerges.

Layer fourth switch when the third layer switch is, it not only applies the IP switching technology in the third layer switch, can view the third layer of data header source address and destination address content, can be based on the observed information to take corresponding actions to achieve bandwidth allocation, fault diagnosis and tcp/ The key function of IP application Data flow for access control.

Layer Fourth Exchange supports other functions besides load balancing, such as the transport flow control function based on application type and user ID. Using multi-level queuing technology, layer fourth switches can label the transport flow and assign priority to the transport stream according to the application.

In addition, layer fourth switches are placed directly on the front of the server to understand the application session content and user permissions, making it an ideal platform to prevent unauthorized access to the server.

And even more surprising is that the current switch technology to the seventh layer of impact, the seventh layer of intelligence can be further control, that is, all the transmission flow and content control.

Currently there is no specific standard for the seventh-tier switching function. But the biggest advantage between tier seventh switching and similar solutions is that switching technology has the biggest advantage of high-speed and does not affect intelligent processing.

Using layer seventh switching technology, the user can make the decision of the transmission flow content more intelligently with the Exchange line speed.

Seven-layer switching enables efficient data flow optimization and intelligent load balancing. Users will be free to make decisions based on the information they receive on all types of transport streams and their purposes, thereby optimizing network access and providing better service to end users.