2. Introduction to Computer Networks Introduction to Computer Networks

3. The Network Interface Card Network interface cards (NICs) provide the interface between cables and computers. This lesson explores the many different types of cards and how their performance affects a network.

4. The Role of the NIC NICs, act as the physical interface or connection between the computer and the network cable.NICs, act as the physical interface or connection between the computer and the network cable. The NIC contains the hardware and firmware (software routines stored in read-only memory, ROM) programming that implements the Logical Link Control and Media Access Control functions.The NIC contains the hardware and firmware (software routines stored in read-only memory, ROM) programming that implements the Logical Link Control and Media Access Control functions.

5. The Role of the NIC Prepare data from the computer for the network cable.Prepare data from the computer for the network cable. Send the data to another computer.Send the data to another computer. Control the flow of data between the computer and the cabling system.Control the flow of data between the computer and the cabling system. Receive incoming data from the cable and translate it into bytes that can be understood by the computer's central processing unit (CPU).Receive incoming data from the cable and translate it into bytes that can be understood by the computer's central processing unit (CPU).

6. Network Address (MAC Address) NIC also has to advertise its own location, or address, to the rest of the network to distinguish it from all the other cards on the network.NIC also has to advertise its own location, or address, to the rest of the network to distinguish it from all the other cards on the network. A committee of the Institute of Electrical and Electronics Engineers (IEEE) assigns blocks of addresses to each NIC manufacturer. The manufacturers hardwire these addresses into chips on the card by a process known as "burning" the address into the card.A committee of the Institute of Electrical and Electronics Engineers (IEEE) assigns blocks of addresses to each NIC manufacturer. The manufacturers hardwire these addresses into chips on the card by a process known as "burning" the address into the card. Each NIC— and therefore each computer — has an unique address (MAC address) on a network.Each NIC— and therefore each computer — has an unique address (MAC address) on a network.

7. Configuration Options and Settings Network interface cards often have configurable options that must be set in order for the card to function properly.Network interface cards often have configurable options that must be set in order for the card to function properly. The following are examples of configurable options:The following are examples of configurable options: Interrupt (IRQ)Interrupt (IRQ) Base input/output (I/O) port addressBase input/output (I/O) port address Base memory addressBase memory address TransceiverTransceiver

8. Configuration Options and Settings Network interface cards often have configurable options that must be set in order for the card to function properly.Network interface cards often have configurable options that must be set in order for the card to function properly. The following are examples of configurable options:The following are examples of configurable options: Interrupt (IRQ)Interrupt (IRQ) Base input/output (I/O) port addressBase input/output (I/O) port address Base memory addressBase memory address TransceiverTransceiver

9. Selecting the Transceiver 2(9) EGA/VGA Adapter 3 Available (Serial port [COM2, COM4] or bus mouse) 4 COM1, COM3 5 Available (parallel port [LPT2] or sound card) 6 Floppy-disk controller 7 Parallel port (LPT1) 8 Real-time clock 10 Available 11 Available 12 Mouse (PS/2) 13 Math coprocessor 14 Hard-disk controller 15 Available (secondary hard-disk controller)2(9) EGA/VGA Adapter 3 Available (Serial port [COM2, COM4] or bus mouse) 4 COM1, COM3 5 Available (parallel port [LPT2] or sound card) 6 Floppy-disk controller 7 Parallel port (LPT1) 8 Real-time clock 10 Available 11 Available 12 Mouse (PS/2) 13 Math coprocessor 14 Hard-disk controller 15 Available (secondary hard-disk controller)

10. NIC, Bus, and Cable Compatibility To ensure compatibility between the computer and the network, the NIC must:To ensure compatibility between the computer and the network, the NIC must: Fit with the computer's internal structure (data bus architecture).Fit with the computer's internal structure (data bus architecture). Have the right type of cable connector for the cabling.Have the right type of cable connector for the cabling. Data Bus Architecture:Data Bus Architecture: Industry Standard Architecture (ISA)Industry Standard Architecture (ISA) Extended Industry Standard Architecture (EISA)Extended Industry Standard Architecture (EISA) Micro Channel ArchitectureMicro Channel Architecture Peripheral Component Interconnect (PCI)Peripheral Component Interconnect (PCI)

11. NIC, Bus, and Cable Compatibility

12. Network Cabling and Connectors To select the appropriate NIC for your network, you first need to determine the type of cabling and cabling connectors it will have.To select the appropriate NIC for your network, you first need to determine the type of cabling and cabling connectors it will have. Some NICs have more than one interface connector.Some NICs have more than one interface connector.

13. Network Performance (1) You can speed up the movement of data through the card by adding the following enhancements:You can speed up the movement of data through the card by adding the following enhancements: Direct memory access (DMA): With this method, the computer moves data directly from the NIC's buffer to the computer's memory, without using the computer's microprocessor.Direct memory access (DMA): With this method, the computer moves data directly from the NIC's buffer to the computer's memory, without using the computer's microprocessor. Shared adapter memory: In this method, the NIC contains RAM that it shares with the computer. The computer identifies this RAM as if it is actually installed in the computer.Shared adapter memory: In this method, the NIC contains RAM that it shares with the computer. The computer identifies this RAM as if it is actually installed in the computer. Shared system memory: In this system, the NIC's processor selects a section of the computer's memory and uses it to process data.Shared system memory: In this system, the NIC's processor selects a section of the computer's memory and uses it to process data.

14. Network Performance (2) Bus mastering: the NIC takes temporary control of the computer's bus, bypasses the computer's CPU, and moves data directly to the computer's system memory. This speeds up operations by freeing the computer's processor to deal with other tasks. Bus mastering can improve network performance by 20 to 70 percent.Bus mastering: the NIC takes temporary control of the computer's bus, bypasses the computer's CPU, and moves data directly to the computer's system memory. This speeds up operations by freeing the computer's processor to deal with other tasks. Bus mastering can improve network performance by 20 to 70 percent. RAM buffering: Network traffic often travels too fast for most NICs to handle. RAM chips on the NIC serve as a buffer. When the card receives more data than it can process immediately, the RAM buffer holds some of the data until the NIC can process it. This speeds up the card's performance and helps keep the card from becoming a bottleneck.RAM buffering: Network traffic often travels too fast for most NICs to handle. RAM chips on the NIC serve as a buffer. When the card receives more data than it can process immediately, the RAM buffer holds some of the data until the NIC can process it. This speeds up the card's performance and helps keep the card from becoming a bottleneck.

15. Network Performance (3) On-board microprocessor With a microprocessor, the NIC does not need the computer to help process data. Most cards feature their own processors that speed network operations.On-board microprocessor With a microprocessor, the NIC does not need the computer to help process data. Most cards feature their own processors that speed network operations.

16. Specialized NICs Wireless NICs: These NICs can be used to create an all- wireless LAN or to add wireless stations to a cabled LAN.Wireless NICs: These NICs can be used to create an all- wireless LAN or to add wireless stations to a cabled LAN. Usually, these NICs are used to communicate with a component called a wireless concentrator that acts as a transceiver to send and receive signals.Usually, these NICs are used to communicate with a component called a wireless concentrator that acts as a transceiver to send and receive signals. Fiber-Optic NICs: fiber-optic network cards allow direct connections to high-speed fiber-optic networks.Fiber-Optic NICs: fiber-optic network cards allow direct connections to high-speed fiber-optic networks. Remote-Boot PROMs: With remote-boot PROMs, diskless workstations can join the network when they start.Remote-Boot PROMs: With remote-boot PROMs, diskless workstations can join the network when they start.