With the continuous improvement of network hardware performance and the continuous reduction of costs, the newly established campus networks basically use advanced Gigabit network technology, and their core switches use Layer 3 switches, which can well support virtual local area networks ( VLAN) technology, which plays a very important role in facilitating the management of the campus network and ensuring the high-speed and reliable operation of the campus network.
What is VLAN
VLAN (VirtualLocalAreaNetwork), also known as virtual local area network, refers to an end-to-end logical network that can span different network segments and different networks built on the basis of a switched LAN and using network management software. A VLAN forms a logical subnet, that is, a logical broadcast domain, which can cover multiple network devices, allowing network users in different geographic locations to join a logical subnet.
Conditions for forming a VLAN
A VLAN is a logical subnet based on a physical network. Therefore, the establishment of a VLAN requires corresponding network equipment that supports VLAN technology. When the different VLANs in the network communicate with each other, the support of routing is needed. At this time, routing equipment needs to be added-to realize the routing function, either a router or a three-layer switch can be used.
The basic strategy of dividing VLAN
From a technical point of view, VLAN division can be based on different principles. Generally, there are three division methods as follows:
1. Port-based VLAN division
This division is to divide several ports on one or more switches into a logical group, which is the simplest and most effective division method. In this method, the network administrator only needs to re-allocate the switch port of the network device, regardless of the device connected to the port.
2. VLAN division based on MAC address
The MAC address actually refers to the identifier of the network card, and the MAC address of each network card is unique and fixed on the network card. The MAC address is represented by a 12-digit hexadecimal number, the first 8 digits are the manufacturer's identification, and the last 4 digits are the network card's identification. The network administrator can divide some sites into a logical subnet according to the MAC address.
3. VLAN division based on routing
The routing protocol works at the network layer, and the corresponding working devices include routers and routing switches (ie, Layer 3 switches). This method allows one VLAN to span multiple switches, or one port is located in multiple VLANs.
For now, the first and third methods mentioned above are mainly adopted for the division of VLANs, and the second method is an auxiliary scheme.
Advantages of using VLAN
Using VLAN has the following advantages:
1. Control the broadcast storm
A VLAN is a logical broadcast domain. Through the creation of VLANs, broadcasts are isolated, the broadcast range is narrowed, and the occurrence of broadcast storms can be controlled.
2. Improve overall network security
Through VLAN division principles such as routing access lists and MAC address allocation, user access rights and the size of logical network segments can be controlled, and different user groups can be divided into different VLANs, thereby improving the overall performance and security of the switched network.
3. Simple and intuitive network management
For switched Ethernet, if the network segment is re-allocated for some users, the network administrator needs to re-adjust the physical structure of the network system, or even need to add network equipment, which increases the workload of network management. For networks using VLAN technology, a VLAN can divide network users in different geographical locations into a logical network segment according to department functions, object groups, or applications. The workstation can be moved between workgroups or subnets at will without changing the physical connection of the network. The use of virtual network technology greatly reduces the burden of network management and maintenance, and reduces network maintenance costs. In a switched network, VLAN provides a flexible combination mechanism of network segments and institutions.
Layer 3 switching technology
Traditional routers have functions such as routing and forwarding, firewalls, and isolating broadcasts in the network. However, in a network where VLANs are divided, the communication between logically divided network segments still needs to be forwarded through routers. Since the amount of communication data between different VLANs is very large on a local area network, if the router wants to route each data packet once, as the amount of data on the network continues to increase, the router will be overwhelmed and the router will Become a bottleneck in the operation of the entire network.
Under this circumstance, the third layer switching technology appears, which is a technology that combines routing technology and switching technology into one. After the Layer 3 switch routes the first data flow, it will generate a MAC address and IP address mapping table. When the same data flow passes again, it will pass through the second layer directly according to this table instead of routing again. It eliminates the network delay caused by the router's routing selection, improves the efficiency of data packet forwarding, and eliminates the network bottleneck problem that the router may generate. It can be seen that the Layer 3 switch integrates routing and switching, and realizes routing inside the switch, which improves the overall performance of the network.
In a gigabit network with a three-layer switch as the core, in order to ensure the convenience and security of management of different functional departments and the stability of the entire network operation, VLAN technology can be used to divide the virtual network. The VLAN subnet isolates the broadcast storm and implements security protection for some important departments; and when the physical location of a certain department changes, you only need to set the switch to reorganize the network, which is very convenient, fast, and saves cost.
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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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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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