VLAN
VLAN is the logical combination of switch ports.
VLAN works in the second layer of OSI (data link layer). A VLAN is a broadcast domain. The communication between VLANs is completed through the router of the third layer.
VLAN has the following advantages:
The broadcast problem of control network: each VLAN is a broadcast domain, and the broadcast on one VLAN will not spread to another VLAN;
Simplify network management: when the user's location in VLAN moves, the network administrator only needs to set a few commands;
Improve network security: VLAN can control broadcast; There is no direct communication between VLANs.
The common methods to define which VLAN the switch port is on are as follows:
Port based VLAN: the administrator designates a port of the switch as a member of a VLAN;
VLAN based on MAC address: the switch decides which VLAN to place according to the MAC address of the node.
Trunk
When a VLAN crosses different switches, it is necessary to use trunk to communicate with computers on the same VLAN but on different switches. Trunk technology enables multiple VLAN information to be transmitted on a physical line. The switch receives data from the port of a VLAN (for example, vlan3). Before transmission on trunk link, a mark will be added to indicate that the data is vlan3; When it arrives at the opposite switch, the switch will remove the mark and send it only to the port belonging to vlan3.
There are two common frame marking technologies: Isl and 802.1Q.
ISL technology adds a new frame header to the original frame and regenerates the frame comparison sequence (FCS). ISL is a unique technology of Cisco, so it can not be used between Cisco switch and non Cisco switch. The 802.1Q technology inserts the label field after the source MAC address field of the original frame, and replaces the original FCS field with the new FCS field. This technology is an international standard and is supported by all manufacturers.
Whether the link between Cisco switches forms trunk can be automatically negotiated. This protocol is called DTP (dynamic trunk protocol). DTP can also negotiate the type of trunk link encapsulation.
VTP
VTP (VLAN trunk protocol) provides a method for managing VLANs on switches. This protocol enables us to create, modify and delete VLANs on one or several central points (servers). VLAN information is automatically spread to other switches through trunk links, and any switch participating in VTP can accept these modifications, All switches keep the same VLAN information.
VTP is organized into a VTP domain. Switches in the same domain can share VLAN information. According to the different functions of switches in VTP domain, VTP can be divided into three modes
Server mode: VLAN can be created, modified and deleted on VTP server, and the information will be announced to other switches in the domain. By default, the switch is in server mode. Each VTP domain must have at least one server, and there can be multiple VTP servers in the domain.
Client mode: it is not allowed to create, modify or delete VLAN on VTP client, but it will listen to VTP announcements from other switches and change its own VLAN information. The received VTP information will also be forwarded to other switches on the trunk link, so this switch can also act as a VTP relay.
Transparent mode: switches in this mode do not participate in VTP. VLANs can be created, modified and deleted on switches in this mode, but the VLAN information will not be announced to other switches, and it will not accept VTP announcement from other switches and update its own VLAN information. However, it should be noted that it forwards the received VTP notifications through the trunk link, thus acting as a VTP relay. Therefore, the switch can be regarded as transparent.
VTP announcement is sent in the form of multicast frame. There is a field in VTP announcement called revision, and the initial value is 0. As long as a VLAN is created, modified or deleted on the VTP server, the revision of the announcement is increased by 1, and the VLAN change information is also included in the announcement. It should be noted that high revision announcements will override low revision announcements regardless of who is the server or client. The switch only accepts higher notifications than the resivision number stored locally; If the switch receives the announcement with lower resivison number, it will reverse overlay with its own VLAN information.
EtherChannel
EtherChannel is developed by Cisco company, which is used in the multi link binding technology between switches. Its basic principle is that multiple fast Ethernet or Gigabit Ethernet physical links between two devices are bound together to form a logical link, so as to achieve the purpose of bandwidth doubling. In addition to increasing the bandwidth, EtherChannel can also distribute the traffic evenly on multiple links to share the load; When one or more links fail, as long as the links are normal, the traffic will be transferred to other links, and the whole process will be completed in a few milliseconds, so as to play the role of redundancy and enhance the stability and security of the network.
In EtherChannel, the load distribution on each link can be based on source IP address, destination IP address, source MAC address, destination MAC address, source IP address and destination IP address combination, source MAC address and destination MAC address combination, etc.
Whether EtherChannel is formed between two switches can also be automatically negotiated by protocol. At present, there are two negotiation agreements: PagP and LACP. The former is a proprietary agreement of Cisco, while LACP is a public standard.
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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 .
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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 .
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For Warranty .
Contact US--->>Return the item to us--->>Receive and send another replace .
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