1. Definition
A virtual local area network (VLAN) is a group of logical devices and users. These devices and users are not restricted by their physical location. They can be organized according to factors such as functions, departments, and applications, and they communicate with each other as if they are in The same in the same network segment, hence the name virtual local area network. VLAN is a relatively new technology. It works on the second and third layers of the OSI reference model. A VLAN is a broadcast domain, and the communication between VLANs is completed by the router on the third layer. Compared with traditional local area network technology, VLAN technology is more flexible, and it has the following advantages: Reduced management overhead for the movement, addition and modification of network equipment; can control broadcast activities; can improve network security.
In a computer network, a Layer 2 network can be divided into multiple different broadcast domains. A broadcast domain corresponds to a specific user group. By default, these different broadcast domains are isolated from each other. To communicate between different broadcast domains, one or more routers are required. Such a broadcast domain is called a VLAN. 2. Several divisions of VLAN. In fact, VLAN is the abbreviation of Virtual Local Area Network (Virtual Local Area Network), which is an emerging of virtual working group by dividing the devices in the LAN logically rather than physically into individual network segments. technology. VLAN is proposed to solve the broadcast problem and security of Ethernet. It adds VLAN header on the basis of Ethernet frame, uses VLAN ID to divide users into smaller working groups, and restricts users between different working groups. Inter-layer visits, each working group is a virtual local area network. The advantage of a virtual local area network is that it can limit the broadcast range and form a virtual work group to dynamically manage the network. VLAN technology allows network managers to logically divide a physical LAN into different broadcast domains, namely VLANs. Each VLAN contains a group of computer workstations with the same requirements and has the same attributes as the physical LAN. But because it is logically rather than physically divided, each workstation in the same VLAN does not need to be placed in the same physical space, that is, these workstations do not necessarily belong to the same physical LAN network segment. Broadcast and unicast traffic within a VLAN will not be forwarded to other VLANs, even if two computers have the same network segment, but they do not have the same VLAN number, their respective broadcast streams will not be forwarded to each other. Helps control traffic, reduce equipment investment, simplify network management, and improve network security.
1. Divide VLAN according to port
Many VLAN vendors use switch ports to divide VLAN members. The configured ports are all in the same broadcast domain. For example, ports 1, 2, 3, 4, and 5 of a switch are defined as virtual network AAA, and ports 6, 7, and 8 of the same switch form virtual network BBB. Doing so allows communication between the ports and allows the upgrade of shared networks. However, this division mode restricts the virtual network to one switch.
The second-generation port VLAN technology allows VLANs to be divided across multiple different ports of multiple switches, and several ports on different switches can form the same virtual network.
The network members are divided by switch ports, and the configuration process is simple and straightforward. Therefore, from the current point of view, this method of dividing VLANs according to ports is still the most commonly used method.
2. Divide VLAN according to MAC address
This method of dividing VLANs is based on the MAC address of each host, that is, each host with a MAC address is configured to which group it belongs to. The biggest advantage of this method of dividing VLANs is that when the user's physical location moves, that is, when changing from one switch to another, the VLAN does not need to be reconfigured. Therefore, it can be considered that this method of dividing based on the MAC address is based on the user's VLAN. The disadvantage of this method is that during initialization, all users must be configured. If there are hundreds or even thousands of users, the configuration is very tiring. Moreover, this method of division also leads to a reduction in the efficiency of the switch, because there may be many members of the VLAN group on each switch port, so that broadcast packets cannot be restricted. In addition, for users of laptop computers, their network cards may be replaced frequently, so VLANs must be continuously configured.
3. Divide VLANs according to the network layer
This method of dividing VLANs is based on the network layer address or protocol type (if multiple protocols are supported) of each host. Although this method of dividing is based on network addresses, such as IP addresses, it is not a route. Routing has nothing to do with it.
The advantage of this method is that the user's physical location is changed, there is no need to reconfigure the VLAN to which it belongs, and VLANs can be divided according to the protocol type, which is very important for network administrators, and this method does not require additional Frame tags are used to identify VLANs, which can reduce network traffic.
The disadvantage of this method is low efficiency, because it takes processing time to check the network layer address of each data packet (compared to the previous two methods). The general switch chip can automatically check the Ethernet frame of the data packet on the network. Header, but for the chip to check the IP frame header, higher technology is required, and it is also more time-consuming. Of course, this is related to the implementation methods of various vendors.
4. Divide VLAN according to IP multicast
IP multicast is actually a VLAN definition, that is, a multicast group is considered to be a VLAN. This method of division expands the VLAN to the WAN, so this method has greater flexibility and is easy to pass through the router. Expansion, of course, this method is not suitable for LAN, mainly because of inefficiency.
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How far(long) the transmitter cover?
The transmission range depends on many factors. The true distance is based on the antenna installing height , antenna gain, using environment like building and other obstructions , sensitivity of the receiver, antenna of the receiver . Installing antenna more high and using in the countryside , the distance will much more far.
EXAMPLE 5W FM Transmitter use in the city and hometown:
I have a USA customer use 5W fm transmitter with GP antenna in his hometown ,and he test it with a car, it cover 10km(6.21mile).
I test the 5W fm transmitter with GP antenna in my hometown ,it cover about 2km(1.24mile).
I test the 5W fm transmitter with GP antenna in Guangzhou city ,it cover about only 300meter(984ft).
Below are the approximate range of different power FM Transmitters. ( The range is diameter )
0.1W ~ 5W FM Transmitter ：100M ~1KM
5W ~15W FM Ttransmitter : 1KM ~ 3KM
15W ~ 80W FM Transmitter : 3KM ~10KM
80W ~500W FM Transmitter : 10KM ~30KM
500W ~1000W FM Transmitter : 30KM ~ 50KM
1KW ~ 2KW FM Transmitter : 50KM ~100KM
2KW ~5KW FM Transmitter : 100KM ~150KM
5KW ~10KW FM Transmitter : 150KM ~200KM
How to contact us for the transmitter?
Call me +8618078869184 OR
Email me [email protected]
1.How far you want to cover in diameter ?
2.How tall of you tower ?
3.Where are you from ?
And we will give you more professional advice.
About Us
FMUSER.ORG is a system integration company focusing on RF wireless transmission / studio video audio equipment / streaming and data processing .We are providing everything from advice and consultancy through rack integration to installation, commissioning and training.
We offer FM Transmitter, Analog TV Transmitter, Digital TV transmitter, VHF UHF Transmitter, Antennas, Coaxial Cable Connectors, STL, On Air Processing, Broadcast Products for the Studio, RF Signal Monitoring, RDS Encoders, Audio Processors and Remote Site Control Units, IPTV Products, Video / Audio Encoder / Decoder, designed to meet the needs of both large international broadcast networks and small private stations alike.
Our solution has FM Radio Station / Analog TV Station / Digital TV Station / Audio Video Studio Equipment / Studio Transmitter Link / Transmitter Telemetry System / Hotel TV System / IPTV Live Broadcasting / Streaming Live Broadcast / Video Conference / CATV Broadcasting system.
We are using advanced technology products for all the systems, because we know the high reliability and high performance are so important for the system and solution . At the same time we also have to make sure our products system with a very reasonable price.
We have customers of public and commercial broadcasters, telecom operators and regulation authorities , and we also offer solution and products to many hundreds of smaller, local and community broadcasters .
FMUSER.ORG has been exporting more than 15 years and have clients all over the world. With 13 years experience in this field ,we have a professional team to solve customer's all kinds of problems. We dedicated in supplying the extremely reasonable pricing of professional products & services. Contact email : [email protected]
Our Factory
We have modernization of the factory . You are welcome to visit our factory when you come to China.
At present , there are already 1095 customers around the world visited our Guangzhou Tianhe office . If you come to China , you are welcome to visit us .
At Fair
This is our participation in 2012 Global Sources Hong Kong Electronics Fair . Customers from all over the world finally have a chance to get together.
Where is Fmuser ?
You can search this numbers " 23.127460034623816,113.33224654197693 " in google map , then you can find our fmuser office .
FMUSER Guangzhou office is in Tianhe District which is the center of the Canton . Very near to the Canton Fair , guangzhou railway station, xiaobei road and dashatou , only need 10 minutes if take TAXI . Welcome friends around the world to visit and negotiate .
Contact: Sky Blue
Cellphone: +8618078869184
WhatsApp: +8618078869184
Wechat: +8618078869184
E-mail: [email protected]
QQ: 727926717
Skype: sky198710021
Address: No.305 Room HuiLan Building No.273 Huanpu Road Guangzhou China Zip:510620
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English: We accept all payments , such as PayPal, Credit Card, Western Union, Alipay, Money Bookers, T/T, LC, DP, DA, OA, Payoneer, If you have any question , please contact me [email protected] or WhatsApp +8618078869184
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We recommend you use Paypal to buy our items ,The Paypal is a secure way to buy on internet .
Every of our item list page bottom on top have a paypal logo to pay.
Credit Card.If you do not have paypal,but you have credit card,you also can click the Yellow PayPal button to pay with your credit card.
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But if you have not a credit card and not have a paypal account or difficult to got a paypal accout ,You can use the following:
Western Union.  www.westernunion.com
Pay by Western Union to me :
First name/Given name: Yingfeng
Last name/Surname/ Family name: Zhang
Full name: Yingfeng Zhang
Country: China
City: Guangzhou
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T/T . Pay by T/T (wire transfer/ Telegraphic Transfer/ Bank Transfer)
First BANK INFORMATION (COMPANY ACCOUNT):
SWIFT BIC: BKCHHKHHXXX
Bank name: BANK OF CHINA (HONG KONG) LIMITED, HONG KONG
Bank Address: BANK OF CHINA TOWER, 1 GARDEN ROAD, CENTRAL, HONG KONG
BANK CODE: 012
Account Name : FMUSER INTERNATIONAL GROUP LIMITED
Account NO. : 012-676-2-007855-0
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Second BANK INFORMATION (COMPANY ACCOUNT):
Beneficiary: Fmuser International Group Inc
Account Number: 44050158090900000337
Beneficiary's Bank: China Construction Bank Guangdong Branch
SWIFT Code: PCBCCNBJGDX
Address: NO.553 Tianhe Road, Guangzhou, Guangdong,Tianhe District, China
**Note: When you transfer money to our bank account, please DO NOT write anything in the remark area, otherwise we won't be able to receive the payment due to government policy on international trade business.
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* It will be sent in 1-2 working days when payment clear.
* We will send it to your paypal address. If you want to change address, please send your correct address and phone number to my email [email protected]
* If the packages is below 2kg,we will be shipped via post airmail, it will take about 15-25days to your hand.
If the package is more than 2kg,we will ship via EMS , DHL , UPS, Fedex fast express delivery,it will take about 7~15days to your hand.
If the package more than 100kg , we will send via DHL or air freight. It will take about 3~7days to your hand.
All the packages are form China guangzhou.
* Package will be sent as a "gift" and declear as less as possible,buyer don't need to pay for "TAX".
* After ship, we will send you an E-mail and give you the tracking number.
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For Warranty .
Contact US--->>Return the item to us--->>Receive and send another replace .
Name: Liu xiaoxia
Address: 305Fang HuiLanGe HuangPuDaDaoXi 273Hao TianHeQu Guangzhou China.
ZIP:510620
Phone: +8618078869184
Please return to this address and write your paypal address,name,problem on note: |
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