Chapter 4 Network Interface Cards

Guide to Networking Essentials

Fifth Edition

Chapter 4

Network Interface Cards

Guide to Networking Essentials, Fifth Edition 2

Objectives

•

Describe a network interface card’s function and

configurable options

•

List important factors for selecting network adapters

•

Describe types of special-purpose network interface

cards

•

Explain the role of driver software in network

adapters

Guide to Networking Essentials, Fifth Edition 3

Network Interface Cards (NIC) Basics

•

For any computer, a network interface card (NIC)

performs two crucial tasks

–

Establishes and manages the computer’s network

connection

–

Translates digital computer data into signals

(appropriate for the networking medium) for outgoing

messages, and translates signals into digital

computer data for incoming messages

•

NIC establishes a link between a computer and a

network, and then manages that link

Guide to Networking Essentials, Fifth Edition 4

From Parallel to Serial and Vice Versa

•

NICs also manage transformations in network

data’s form

–

The computer bus has series of parallel data lines

•

Parallel transmission

•

For nearly all forms of networking media, signals

traversing the media consist of a linear sequence

of information that corresponds to a linear

sequence of bits of data (serial transmission)

•

To redistribute serial data to parallel lines (and vice

versa), one of the most important components on a

NIC is memory, which acts as a buffer

Guide to Networking Essentials, Fifth Edition 5

From Parallel to Serial and Vice Versa

(continued)

Bus width

Guide to Networking Essentials, Fifth Edition 6

From Parallel to Serial and Vice Versa

(continued)

Guide to Networking Essentials, Fifth Edition 7

Additional Functions of a NIC

•

Creates, sends, and receives frames

–

Frame: fundamental unit of data for network

transmission and reception

•

Deals with frame-level errors and incomplete or

unintelligible frame structures

•

Manages access to medium

•

Acts as gatekeeper (permits inbound

communications aimed only at its computer (or

broadcast) to pass through NIC and on to CPU)

–

Each card has a unique MAC address in ROM

–

Promiscuous mode disables gatekeeper functions

Guide to Networking Essentials, Fifth Edition 8

PC Buses

•

When PCs were introduced, only a single bus

design existed: a limited 8-bit bus

•

As technology evolved, other buses came along

–

Peripheral Component Interconnect (PCI)

–

PCI-X

–

PCI Express

–

PCMCIA cards

–

Industry Standard Architecture (ISA)

Guide to Networking Essentials, Fifth Edition 9

PC Buses (continued)

Guide to Networking Essentials, Fifth Edition 10

PC Buses (continued)

Guide to Networking Essentials, Fifth Edition 11

PC Buses (continued)

Guide to Networking Essentials, Fifth Edition 12

Other PC Interfaces Used for

Networking

•

Although the following interface technologies don’t

replace the buses in most typical PCs, they do offer

other ways to attach computers to networks:

–

Universal Serial Bus (USB)

•

USB 1.0 can operate at up to 12 Mbps

•

USB 2.0 can operate at up to 480 Mbps

–

FireWire (also known as IEEE 1394)

•

Can operate up to 400 Mbps

•

IEEE 1394b supports transfer rates up to 3200 Mbps

Guide to Networking Essentials, Fifth Edition 13

Principles of NIC Configuration

•

Microsoft introduced Plug and Play (PnP)

architecture with Windows 95

–

Defines a set of configuration protocols so that a

computer can communicate with its peripherals

during the power-on self test (POST) sequence

and auto-negotiate a working configuration

•

NIC configuration involves modifying settings

–

Interrupt request line (IRQ)

–

Base I/O port

–

Base memory address

Guide to Networking Essentials, Fifth Edition 14

Integrated NICs

•

On-board NICs: Most PC motherboard and laptop

computer manufacturers integrate the network

interface directly on to the motherboard

–

Might not meet a user’s needs

•

Wrong media

•

Wrong speed

•

Wrong architecture

–

Most on-board NICs are suitable for most users’

requirements

Guide to Networking Essentials, Fifth Edition 15

Making the Network Attachment

•

NICs perform several vital roles to coordinate

communications between computer and network

–

Establishing a physical link to networking medium

–

Generating signals that traverse networking medium

–

Receiving incoming signals

–

Implementing controls for when to transmit signals to

or receive signals from the network medium

•

It is essential that you matching the adapter you

choose with the medium it must attach to

•

Some NICs support multiple media types, and

configuration is usually automatic or uses SW

Guide to Networking Essentials, Fifth Edition 16

Choosing Network Adapters for Best

Performance

•

The hardware-enhancement NIC options include:

–

Direct Memory Access (DMA)

–

Shared adapter memory

–

Shared system memory

–

Bus mastering

–

RAM buffering

–

On-board co-processors

–

Various security options

–

Traffic management (Quality of Service (QoS))

–

Automatic link aggregation

–

Improved fault tolerance

–

Improved management features

Guide to Networking Essentials, Fifth Edition 17

Choosing Network Adapters for Best

Performance (continued)

•

Increased performance features have payoffs for

servers that might not apply to workstations

–

The following is a checklist for purchasing NICs:

•

Bus width—Higher is better

•

Bus type—Use 64-bit PCI-X or PCIe for servers

•

Memory transfer—Shared memory outpaces I/O

or DMA

•

Special features—Choose security, management,

protocol-handling, and hot-plug capabilities

•

Bus mastering—Important for servers

•

Vendor factors—Look for quality, reliability,

staying power, and reputation

Guide to Networking Essentials, Fifth Edition 18

Special-Purpose NICs

•

In addition to straightforward network adapters,

several types of cards deliver specialized

capabilities

–

They include interfaces for wireless networks, as

well as a feature for so-called diskless workstations

(“thin clients”), which must access the network to

load an OS when they boot

•

These cards are said to support remote booting or

remote initial program load

Guide to Networking Essentials, Fifth Edition 19

Wireless Adapters

•

Wireless interfaces usually incorporate some or all

of the following components:

–

Indoor antenna and antenna cable

–

Software to enable the adapter to work with a

particular network environment

–

Diagnostic software

–

Installation software

•

Wireless NICs are commonly used with an access

point to add wireless elements to an existing LAN

•

Select: speed, wireless standard, other (e.g.,

security)

Guide to Networking Essentials, Fifth Edition 20

Wireless Adapters (continued)

Guide to Networking Essentials, Fifth Edition 21

Remote Boot Adapters

•

The network must be the source of access to the

programs needed to start a diskless workstation

–

Some NICs include a chip socket for a special bit of

circuitry called a Boot PROM, which is referred to as

preboot execution environment (PXE) compliant

–

Remote boot adapters offer several advantages

•

Cost savings because no hard drive is required

•

Improved reliability (hard drives are a common source

of problems)

•

Security is increased (no sensitive data can be stored

on the computer)

•

Virus attacks are useless

Guide to Networking Essentials, Fifth Edition 22

Driver Software

•

Device driver: small, specialized program that

represents a device to an OS and manages

communications between the OS and NIC

•

Incorrect/poorly written drivers can have negative

impact on performance or prevent PC from booting

•

Major vendor standards for drivers

–

Network Device Interface Specification (NDIS)

–

Win32 Driver Model (WDM)

–

Open Data-link Interface (ODI)

•

Installing a driver for a NIC is usually easy

Guide to Networking Essentials, Fifth Edition 23

Driver Software (continued)

Guide to Networking Essentials, Fifth Edition 24

NIC Driver Configuration

Guide to Networking Essentials, Fifth Edition 25

NIC Driver Configuration (continued)

Guide to Networking Essentials, Fifth Edition 26

Wireless NIC Configuration

Guide to Networking Essentials, Fifth Edition 27

Wireless NIC Configuration

(continued)

Guide to Networking Essentials, Fifth Edition 28

Summary

•

NICs supply the interface between a computer and

the networking medium

–

When sending data, a NIC reformats outgoing data

from the parallel form that arrives through the

computer’s bus to the serial form used over most

media; to receive data, the process is reversed

•

NICs have options that must be set for an adapter to

make a working network connection (usually PnP)

•

NIC’s edge connector must match the PC slot

•

Many motherboards have integrated NICs

•

Network adapters can have a profound effect on

overall network performance

Guide to Networking Essentials, Fifth Edition 29

Summary (continued)

•

When purchasing a network adapter, consider the

following checklist: bus width, bus type, memory

transfer, special features (such as security), bus

mastering, and vendor factors (such as support)

•

When purchasing a wireless NIC, keep in mind the

Wi-Fi standard you want to use

•

Driver software permits a NIC to communicate with a

computer’s operating system

–

NIC driver configuration can be auto-configured, or it

might require setting some options