Switches can learn the "mac" address and store it in an internal address sheet by the originators and targets of the data frame
A temporary exchange path is established between the target receiver to enable the data frame to reach the destination address directly from the source address。
Gg: with the development of enterprise network applications, people are no longer satisfied with 100 gigatons of desktop network speed。
Many people are looking for faster local area network connectivity technologies, using gygmy ethernets or faster gigabytes. Well..
The change is not just in the backbone of the park network, it's also in every distribution room, the it manager of the enterprise
It is hoped that each desktop user will be provided 10 times more connected than the previous one
With the development of enterprise network applications, ggx is no longer sufficient for 100 trillion of desktop network speeds。
Many people are looking for faster local area network connectivity technologies, using gygmy ethernets or faster gigabytes. Well..
The change is not just in the backbone of the park network, it's also in every distribution room, the it manager of the enterprise
It is hoped that each desktop user will be provided with 10 times the previous network connection。
The switch is faster than the switch.
Personal computers are not usually used ... It applies to rooms, campuses, it parks, etc. With many computers。
We can check all the explanations
References:
Respondent: yunanchan
1. What is a switch
The switch is also called the switchboard, which regenerated the information and forwarded it internally to the specified
Port, with automatic location capability and exchange function, as the switch will be per
A package is delivered independently from the source port to the destination port, avoiding collisions with other ports. It's a wide-ranging switch
It is a device to complete the clearing-house function in the communications system。
2. The working principles of the switch
In the computer network system, switches were introduced to address weaknesses in shared working patterns. The hub is shared
The mode of work represents that if you compare the hub to a postman, the postman is an unwritten fool."
He didn't know to send the letter directly to the recipient based on the address on the letter. He only sent it with it
Give it to everyone and let the recipient judge it against the address information! And the switch is a hearing."
Ming's postman - switches have a high-bandwidth backline and internal exchange matrix. All ports of the switch
It's all attached to this back bus. When the control circuit receives the data package, the processing port will find the address in the memory
Checklist to determine which nic is attached to the destination mac (hardware address of the card), by
The internal exchange matrix quickly transmits the package to the destination port. If the target mac doesn't exist, the switch is broadcast
There are ports that receive port responses and exchange opportunities to learn about a new address and add it to the internal address list。
See, when you receive a letter from a web card, the switch will be based on the address information above and your hand
The “bookbooks” held by a resident quickly reach the recipients. If the address of the recipient is not in the account book
Up, the switch will distribute the letter to all people like a hub and then find the recipient. And find the receipt
After that, the exchange immediately registered the person's information in the family's “book” so that when the client is served later
The letter could be delivered quickly。
3. Performance characteristics of switches
1) only bandwidth
Because the switch is able to get the data to its destination in an intelligent way based on the address information, it's not going to be like that
This is the case with the "unrecipients" who are disturbed when transmitting data. This way, the switch can run multiple ports at the same time. Group
Between. And each port can be considered to be a stand-alone network, with both parties communicating with each other enjoying all of them alone
The bandwidth does not need to be used in competition with other equipment. For example, when a host sends data to d host, b host
The data can be sent to the c mainframe at the same time, and both transmissions have the full bandwidth of the network -- assuming they use it at this time
It is a 10-mb switch, and the total circulation of the switch at this time is equal to 2 x 10mb = 20mb。
2. Full-time work
When the two ports on the switch communicate, they can be effective because the corridors between them are relatively independent
Full-time communications。
1. Role of routers
Through a hub or switch, we can make up a bigger local area network (figure 3), but..
When the number of machines reaches a certain number, the problem is: for local area networks (lans) made up of hubs
Using the broadcast "work" mode, when the network is larger, the more the information is collided and blocked during transmission
The more serious the situation is, even if there are switches. Second, it's not safe. It's not good
Management。
In order to solve these problems, people have divided a larger network into a small subnet, segment, or directly
Split them into multiple vlans (i. E., virtual local area network) and within one vlan, a host sends a message only
Other hosts with the same vlan are able to send, and other vlan members do not receive this information or broadcast frames。
The introduction of vlan, which divides the network, can effectively contain broadcasting storms on the network and increase network security and management
Control concentration (figure 4)。
Since it's a local area network, what happens when a different vlan host needs to communicate? This is the time
We have to help with the router. Routers can be located in different subnets, sections, vlan
Computers connect, and they communicate freely. Besides, we all know there are many types of structures in the current network
And the protocols and speeds used in different networks vary. When two different structures need to be connected, it's possible
To be achieved through routers. Routers can connect two local area segments of a similar or different system structure
To constitute a larger local area network or a wide area network。
See, a router is a network device that connects multiple networks or segments and allows different networks, segments or vlan
The data information between them is translated “to enable them to read each other's data and understand each other's data, thus constituting a larger one”
The network。
2. The philosophy of routers
Routes are activities that move information from source to target location through interconnected networks. Then the route
How does the machine translate work
Dictionary, through which the conversion between english and chinese is achieved. And for routers, it's used for that
Translation dictionary -- path sheet. Routingtable saves data associated with various transmission paths, e. G. Subs
Information on the logo of the network, the number of routers on the internet and the name of the next router. The path sheet can be used by the system
The administrator has fixed settings that can be modified by system dynamics, can be automatically adjusted by router or host
Control。
The router allows for interconnection of different subnets and segments, so the router is different from the connector, switcher, one of which
It works at the grass-roots level instead of at the hub and switchboard levels. Like a bigger one
Large enterprise local area networks (lans), based on management, safety and performance considerations, typically divide the entire network into multiple categories
Vlan, as such, must use routers when communicating between vlan and vlan。
There is certainly a need to connect to the internet for the enterprise network, and for businesses, it is generally by renting telecommunications
The internet is being used to connect business networks to the internet either through dnn or through adsl, cable, isdn etc
Different networks and protocols used also require routers to complete the interface between enterprise networks and the internet。
Click to zoom in
In general, the information passes through at least one or more intermediate nodes during the route. Usually, people follow the route
The comparison with the exchange is mainly due to the fact that, in the view of ordinary users, the two perform exactly the same functions. In fact
The main difference between route and exchange is that the exchange takes place on the second level of the osi reference model (data chain layer), and
Route occurs on the third level, the network layer. This distinction determines the route and the need for the exchange of mobile information
With different controls, the two functions are performed differently. Routers determine data by route
The transmission. The forwarding strategy is called route selection, which is also the origin of the router name。
The appearance of the three swordsmen
We've explained the workings of the hubs, switches, routers, but for many beginners
On the other hand, it is sometimes hoped that they will be distinguished from their appearance. Of course, the hubs, the switches, the routers are here
There must be some difference in appearances, but these are often used only as reference information
The switch is very similar to the router product. And the hardest part of it is the normal desktop type
Centralists and switches, and routers are relatively easy to identify
Switch working principles
Overview
In 1993, local area network (lan) exchange equipment appeared, and in 1994 there was a boom in the exchange of network technology. In fact
Exchange technology is an exchange product with simplified, low-priced, high performance and high-end port intensity, reflecting bridging skills
The complex exchange techniques of the arts operate on the second tier of the osi reference model. Like the bridge, the switch is in every bag
The mac address is relatively simple to transmit decision information. And this kind of forwarding decision doesn't usually take into account what's hidden in the bag
Additional information. Unlike the bridge, the switch is very slow, operating close to a single local area network (lan) performance, far beyond
It's a re-transmittance between regular bridges。
Exchange technology to allow bandwidth alignment of shared and dedicated lan segments to reduce the flow of information between lans
There are bottlenecks. Ethernets, rapid ethernets, fddis and atm technologies are available for exchange。
Similar to traditional bridges, switches provide many networking features. Switches have economically small networks
Conflict domain, providing higher bandwidth per workstation. The transparency of the protocol makes the switch simple in software configuration
Directly installed in a multi-negotiation network; switchboards using existing cables, repeaters, hubs and workstations
Net cards that do not require high-level hardware upgrades; switchboards are transparent to workstations so that they are less expensive to manage and simplified
Added network nodes, mobile and network change operations。
The use of specially designed integrated circuits allows switches to transmit information at all ports at a circuit rate in parallel
A much higher operational performance than a traditional bridge. If theoretically a single etho-net port pairs of 64 octadecimals
According to the package, a transmission rate of 14880 bps is available. That means one with 12 ports and six parallel numbers
The streamed circuit rate “ethernet exchange” must provide an overall throughput rate of 89280 bps (6 information streams)
X144880bps/channel flow). Specialized integrated circuit technology allows switches to use the above-mentioned characteristics at more ports
It operates at a lower cost than the traditional bridge。
Ii. Transfer technology
Port exchange
Port exchange techniques are first found in slot-type hubs, which typically divide back boards into multiple ethers
Networks (each segment is a broadcast domain) are not connected by bridge or route and are not connected. At big
The main module is inserted and assigned to a backboard segment, where the port is exchanged for the backboard with a too-module port
It's all distributed and balanced between multiple segments. Depending on the level of support, port exchanges can also be broken down into:
Motion & block exchange: migration of entire modules。
Port-group exchange: the ports on the usual module are divided into several groups, each of which allows for network migration。
Port-level exchange: supports the movement of each port between different segments of the network. This exchange is based on osi
A layer of work has the advantages of flexibility and load balance. If it's properly configured, then it's still there
The degree of error was made, but did not change the characteristics of the shared transmission medium and could not be called a real exchange。
2. Frame exchange
Frame exchange is currently the most widely applied local area network (lan) exchange technology, which is available through micro-separation of traditional transmission media
Parallel transmission mechanisms to reduce conflict zones and gain high bandwidth. In general, every company's product realization technology
There are differences, but the web frames are generally treated in the following ways:
Straight-to-to-forward: provide a linear processing capability, and the switch only reads the first 14 bytes of the frame, so that the frame is transmitted
To the appropriate port。
Storage forwarding. Error detection and control by reading web frames。
The first method was exchanged very quickly, but lacked higher control over the frame, intelligence and security
Completeness and inability to support exchange of ports at different rates. As a result, the latter technology was taken seriously by the manufacturers
Point。
Some even decomposition the frame into a fixed-sized letter. Hard
Achievement, speed of processing, and ability to complete advanced controls (e. G., medge's let hub)
Instrument)。
3. Exchange of letters
Atm technology represents the future direction of networking and communication technology development, and it also addresses many of the current difficulties in network communication
Atm uses a fixed length of 53 bytes for the exchange of letters. Owing to its fixed length
With hardware. Atm uses a dedicated non-differentiated connection, operating in parallel, which can be created simultaneously through a switch
Multiple nodes, but without affecting the ability to communicate between each node. Atm also allows at source nodes and targets, sections
Point creation of virtual links to ensure sufficient bandwidth and error tolerance. The atm uses a statistical split
Reuse would greatly improve access. The bandwidth of the atm
