January 28, 2003 Week 4: Day 1
Welcome to Lesson 4 - Network Interface Cards
The sole purpose of a network interface card is to mediate the connection between
the computer and the network medium. This includes managing the physical connection
as well as translating data from the computer into signals appropriate for the
network medium. Network interface cards go by many names including network adapter,
NIC, and just plain network card.
Parallel transmission: Data is sent along a number of lines at the same time. This is the transmission method used within the computer.
Serial transmission: Data is sent in a linear sequence. This is the transmission method used by most network media. One of the jobs of the NIC is to convert the data it receives in parallel to serial for transmission across the network, and perform the reverse operation for incoming data. Figure 4-1 illustrates this function very well.
Bus width: This is the number of parallel lines that make up the computer’s bus. This width is measured in the number of bits, which can be moved in a single bus transfer. The first PCs used an 8-bit bus. The second generation of PCs moves to 16-bit, which became the Industry Standard Architecture (ISA).
As you learned in Chapter 3, the transceiver for a Thickwire network is connected
directly to the backbone. The computer is then attached to the transceiver via
a drop cable. However, most other types of NICs include a transceiver directly
on the card. It is also very common to include multiple transceivers on the
NIC to accommodate different media. Further, the NIC is responsible for packaging
data into packets, which are the fundamental units of data for network communication.
The NIC is also responsible for correcting packet-level errors. The NIC is the
“gatekeeper” for the computer. It examines all packets on the network
as they are sent and determines whether the computer is the destination of any
packet. It does this by examining the destination network address of the packet
and comparing it to its own network address. This process is discussed in more
detail in Chapter 5.
There are five types of PC busses: Industry Standard Architecture (ISA), Enhanced Industry Standard Architecture (EISA), Micro Channel Architecture (MCA), Peripheral Component Interface (PCI), and Accelerated Graphics Port (AGP). These types are illustrated in the interactive exercise for this lesson.
USB is a relatively low-speed serial interface that is very popular for connecting
peripheral devices like mice, keyboards, printers, scanners, and cameras. FireWire
is a high-speed serial bus that operates at up to 3200 Mbps and is governed
by the IEEE 1394 and 1394b standards.
Your company often employs temporary workers to input sensitive data. As your network and database have grown, concern has mounted that the information these workers enter may not be safe, or may be taken off the premises. Your boss has asked you to implement a hardware-based solution to ensure that nothing happens to the data in the system.
This weeks question goes to anyone that wants it!!!
See you on line!
Remember to keep up with your on-line lessons and quizzes!
mdm