Network Adapter:
Network adapters perform all the functions required to communicate on a network.
- They convert data from the form stored in the computer to the form transmitted or received on the cable and provide a physical connection to the network.
- Fiber-optic Ethernet adapters convert the data from 8, 16 or 32 bit words to serial pulses of light.
- Microwave network interfaces convert the computer data to serial radio waves.
- Network adapters receive the data to be transmitted from the motherboard of your computer into a small amount of RAM called a buffer.
- The data in the buffer is moved into a chip that calculates a checksum value for the chunk and add address information, which includes the address of the destination card and its own address.
- Ethernet adapter addresses are permanently assigned when the adapter is made at the factory.
- The network adapter must still convert the serial bits of data to the appropriate media in use on the network.
- Some cards have more than one type of transceiver built in so you can use them with your choice of media.
- While adapters transmit, they listen to the wire to make sure the data on the line matches the data being transmitted.
- If another adapter has interrupted, the data being heard by the transmitting network adapter will not match the data being transmitted.
- If then happens, the adapter ceases transmitting and transmits a solid on state instead, which indicates to all computers that it has detected a collision and that they should discard the current frame because has been corrupted.
- The network adapter waits a random amount of time and then again attempts to transmit the frame.
You have remember some condition for selecting an Adapter:
- What type of network are you attaching to?
- What type of media are you using?
- What type of bus does your computer have?
The Open System Interconnection Model attempts to define rules that apply to the following issues:
- How network devices contact each other and if they have different languages, how they communicate with each other.
- Methods by which a device on a network transmissions are received correctly and by the right recipient.
- Methods to ensure that network transmissions are received correctly and by the right recipient.
- How the physical transmission media are arranged and connected.
- How to ensure that network devices maintain a proper rate of data flow.
- How bits are represented on the network media.
- The OSI model is nothing tangible; if is simply a conceptual framework.
- The OSI model does not perform any functions in the communication process.
- The OSI model simply defines which tasks need to be done and which protocols will handle those tasks, at each of the seven layers of the model.
