What is a layer switch, two-tier switch, three-layer switch? _ Computer Network

Source: Internet
Author: User
Tags switches
I'm going to go down to the two and three layers of the switch.
A two-tier switch is equivalent to dividing an interface into multiple interfaces, just to provide a lot of interfaces; (if the landlord is not a professional person can ignore the following content) theoretically it can be understood that the switch does not split the broadcast domain, but split the conflict domain

The three-tier switch has a certain routing function (do not know how much the landlord knows about the router, if you do not understand, you can directly understand him as to provide data how to go to the thing on it, is to provide data how to go, in layman's terms or in practical applications you have two-tier switch can not connect to the Internet, But you have a three-tier switch to connect to the Internet, but there are a lot of holes in the three-tier switch, he can provide the functions of the switch's multiple interfaces, and also can provide router routing function.

To put it simply:

Layer switch supports only physical layer protocol (telephone program-controlled switchboard can be counted as a???)
Two-tier switches support physical layer and data link layer protocols, such as Ethernet switches
The three-tier switch supports physical layer, data link layer and Network layer protocol, such as some switches that lead the way by function.

From the layered structure of iso/osi, the switch can be divided into two-layer switch, three-layer switch and so on. Two-layer switch refers to the traditional work in the OSI Reference Model of the second layer-the data link layer on the switch, the main features include physical address, error checking, frame sequence and flow control. A pure second-tier solution is the cheapest solution, but it provides the least control in terms of dividing subnets and broadcast restrictions. Traditional routers that work with external switches can also solve the problem, but routers are now processing at a speed that does not match the bandwidth requirements. Therefore, three-tier switches, web switches and so on.
The three-layer switch is a three-layer switching device, the second layer switch with the third-tier routing function, but it is an organic combination of the two, not simply to overlay the hardware and software of the router device on the LAN switch.
Web switches provide management, routing, and load-balancing transmissions for data center devices, including internet servers, firewalls, cache servers, and gateways. Unlike traditional network devices, traditional network devices focus on high-speed completion of a single frame and packet Exchange, while Web Exchange focuses on tracking and processing web sessions. In addition to the connectivity and packet routing provided by traditional second/three-tier switches, Web switches provide a complete strategy for traditional LAN switches and routers, combining local and global server load balancing, access control, quality of service assurance (QoS), and bandwidth management capabilities. At present, the Web switch has been developed from a pure transport layer (layer fourth) to an intelligent exchange based on content (layer seventh). Using content or user classifications for Web request redirection is a feature of the Web server. However, the development of Internet transmission and commerce far exceeds the improvement of computer processing power. Offloading content to a web switch balances the entire site's infrastructure.

------------------Layer 3 switch is to lead the switch by feature!! The 2-tier is based on MAC address access!-------------------------

There are two common types of switches now,

The first is the 2-tier switch, which is the most we see, based on the mac,2 layer for fast switching, with all the interfaces in one broadcast domain.

The second is 3-tier switches, 3-layer switches as the name suggests, that is, the routing function can be used. 3-tier switches require a MSFC (multilayer switching feature card) to support 3-tier routing features, and modern 3-tier switches integrate this functionality.
Example 1_ two-layer switch:
Floor one floor two have two 2 layer switch respectively, they can divide the VLAN, make the strategy to carry on the communication, but if say, the floor 1 of switch and floor 2 of the switch is not on the same VLAN, and they also communicate with each other, then need to do routing function through the router.
Example 2_ three-layer switch:
On the other hand, if there are more floors and more switches, then a 3-tier core switch is needed to replace the router.
The principle of a 3-layer switch is simple: 1 routes are exchanged multiple times.
Explanation: In a wide area network, of course, 3-tier packets (routed) are running, while routing needs to determine the optimal path for each source to the destination, each time a choice is made, and if you use a 3-tier switch, you can route the source to the destination for the first time, and the 3-tier switch will move this data to 2 levels, So the next time, both for the purpose of the source, or for the source to the goal is a quick exchange.
The 1.3-tier switch has a routing function, but it cannot completely replace the router because the underlying principle is not the same.
A 2.3-tier switch is a lot faster than router policy forwarding in a sense!
The 3.3-layer switch can save network resources conveniently and prevent congestion phenomenon.

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