This article is to tell you that the technical content of the three-layer switch is high, not only "looks beautiful", but also is very beautiful! So, what kind of role does the three-layer switches do? What kind of service can the three-layer switch provide us? Can it give us what benefits? In order to answer this question, we specially invited experts from three-layer switch to discuss together, and finally got a satisfactory answer, please taste fine.
Triple switch
1. There is less than three layers of exchange of online backbone.
To say that the role of the three-layer switches in many network devices is not over using the "middle flow column". In the campus network, the urban education network, from the backbone network, the urban network backbone, the gathering layer has three floors, especially the core backbone network must use a three-layer switch, otherwise thousands of networks The computer is in a subnet, not only without security, but also cannot isolate the broadcast storm because of the unable to split the broadcast domain.
If a traditional router is used, although the broadcast can be isolated, the performance is not guaranteed. The three-layer switches have very high performance, and both three-layer routing function, which has two-layer network speed. Layer 2 exchange is based on MAC addressing, three-layer exchange is forwarding traffic based on the third layer address; except for the necessary routing process, most of the data forwarding processes are swapped by Layer 2, improve the efficiency of packet forwarding. .
The three-layer switch implemented the routing function of IP by using the hardware switching mechanism. Its optimized routing software improves the efficiency of the routing process to solve the speed problem of traditional router software routing. Therefore, it can be said that the three-layer switch has a "function of the router, the performance of the switch".
2, the connection subnet does not have three floors
Computers on the same network If more than a certain number (usually in 200 sets, depending on the communication protocol), it is likely that the network transmission efficiency is low due to a large number of broadcasts on the network. In order to avoid broadcasting storms caused by broadcast on large switches, it can be further divided into multiple virtual networks (VLANs). But doing so will result in a problem: communication between VLANs must be implemented through a router. However, the traditional router is also difficult to compete between communication tasks between VLANs, because the network traffic relative to the local area network is too weak, and the routing capacity of traditional ordinary routers is too weak.
And the price of a Gigabit router is also very difficult to accept. If you use a gigabit port or a 100M port on a three-layer switch to connect to different subnets or VLANs, under the premise of maintaining performance, there is a problem that the subnet must rely on the router to communicate between the subnets after the subnet division. Therefore, the three-layer switch is an ideal device that connects the subnet.
The benefits of using a three-layer switch
In addition to excellent performance, the three-layer switch also has some traditional two-layer switches, which can bring many benefits to the construction of campus network and metro education network, and listed below.
1, high expandability
When the three-layer switch is connected to multiple subnets, the subnet is only established with the Layer 3 switch module, and does not increase the port as the traditional external router, thereby protecting the user's investment in the campus network and metro education network. And meet the needs of rapid growth of network applications from 3 to 5 years.
2, cost-effective
The three-layer switch has the ability to connect large networks, which can basically replace certain traditional routers, but the price is close to the Layer 2 switch. Now the price of a 100-spendle switch is only tens of thousands, and the price of the high-end Layer 2 switch is similar.
3, built-in security mechanism
The three-layer switch can achieve one-way or bidirectional communication between different VLANs as the normal router, with the function of accessing the list. If set in the access list, you can limit the user to the specific IP address so that the school can prohibit students from accessing unhealthy sites.
The access list can not only be used to ban internal users from accessing certain sites, but also to prevent illegal users from the outside of the campus network, the external education network access to the network resources inside the campus network, the interior of the metro education network, thereby improving the security of the network. 4, suitable for multimedia transmission
Education network often needs to transmit multimedia information, this is a feature of education network. The three-layer switch has the control function of QoS (service quality), which can assign different bandwidth to different applications.
For example, when the video flow is transmitted in the campus network, the video stream can be transmitted specifically for video transmission, which is equivalent to opening a dedicated channel in the network, and other applications cannot occupy these reservations. Bandwidth, can therefore guarantee the stability of video streaming. The ordinary Layer 2 switch does not have this characteristic, so when transmitting video data, there will be a video and suddenly slowed jitter phenomenon.
In addition, video on demand (VOD) is also often used in education networks. However, since some video-on-demand systems use broadcasts to transmit, the broadcast package cannot achieve cross-network segments, so that the VOD cannot achieve cross-network segments; if the VOD is implemented in the form of unicast, although cross-network segment, but support At the same time, there is very little connection, and dozens of connections take up all bandwidth. The three-layer switch has a multicast function, and the VOD packet is transmitted in various subnets in the form of multicast, which enables both network segment transmission, and the performance of the VOD is guaranteed.
5, billing function
In colleges and campus networks and metro education networks in some areas, it is likely to have billing requirements, because the three-layer switch can identify IP address information in the packet, so the data traffic of the computer can be statistially, which can be based on the flow meter. Fees, you can also count the computer to be connected to the network, and bill charges. And ordinary Layer 2 switches are difficult to do this.
Nowadays, the country has set off a boom of building campus network, Metropolitan Education Network. I believe that three-layer switches are in this boom in this boom in this boom in their excellent performance, moderate prices.
