Chapter Six

Networking

Hardware

Network Interface Cards (NICs)

Connectivity devices enabling a workstation, server, printer or other node to receive and transmit data over the network media

Sometimes called network adapters NICs are physical and data link layer

devices

Network Interface Cards (NICs)

Types of NICs Industry Standard

Architecture (ISA) MicroChannel

Architecture (MCA) Extended Industry

Standard Architecture (EISA)

Peripheral Component Interconnect (PCI)

FIGURE 6-1 Four primary bus architectures

Network Interface Cards (NICs)

NICs may connect to interfaces other than a PC’s bus. For example:– For laptop computers, Personal Computer Memory

Card International Association slots may be used to connect NICs

• PCMCIA

• Also called PC card

• Developed in the early 1990s to provide a standard interface for connecting any type of device to a portable computer

Network Interface Cards (NICs)

FIGURE 6-3 Typical PCMCIA NIC

FIGURE 6-4 Parallel port NIC

Network Interface Cards (NICs)

FIGURE 6-5 Wireless NIC and transceiver

FIGURE 6-6 Ethernet NICs for printers

Network Interface Cards (NICs)

Installing NICs– Installing hardware– Configuring software

• Installing driver—software the tells OS how to communicate with NIC

• Specifying IRQ, memory range, I/O port

– Configuring firmware• Utilities supplied with NIC that enables you to write

configuration changes to the EPROM chip on the NIC card

Installing and Configuring NIC Software

After NIC is physically installed, restart the PC

The driver for the NIC card must be installed and configuration information entered

Repeaters

Connectivity device that regenerates and amplifies an analog or digital signal

FIGURE 6-14 Repeater

Hubs

Multiport repeater containing one port that connects to a network’s backbone and multiple ports that connect to a group of workstations

Hubs

Passive hubs– Only repeats signal

Active hubs– Regenerate or amplify

signal

Intelligent hubs– Possesses processing

capabilities

Standalone Hubs– Serves a workgroup of computers that are

separated from the rest of the network Stackable Hubs

– Designed to be linked with other hubs in a single telecommunications closet

Modular Hubs andIntelligent Hubs

Modular hub– Provide a number of interface options within

one chassis• Connection point for networks using with different

cabling, e.g., 10base2 and 10baseT

Intelligent hubs– Also called managed hubs– MIB (management information base)

• Collection of data used by management programs to analyze network performance

Choosing the Right Hub

Performance Cost Size and growth Security Management benefits Reliability

Bridges

Reduce network traffic bottleneck

Regenerate signals to extend network lengths

Operate at the Data Link Layer of the OSI model because they have to read packet addresses

Bridges Filtering database

– Collection of data created and used by a bridge that correlates the MAC addresses of connected workstations with their locations

– Also known as a forwarding table

Segment 1

Segment 2

Bridge

Bridges

Transparent Bridging– Method used on most Ethernet networks

Source Route Bridging– Method used on most Token Ring networks

Translation Bridging– Method that can connect Token Ring and

Ethernet networks

Switches

Switches subdivide a network into smaller logical pieces

Collision domain– Portion of a LAN

encompassing devices that may cause and detect collisions among their group

Switches are layer 2 devices

Switches

Switch Methods– Cut-through mode—switch reads only the

header to determine where to forward the packet.

– Store and forward mode—switch reads the entire packet and checks for accuracy before forwarding

Using Switches to Create VLANs

Virtual local area networks (VLANs)– Means by which a

switch can logically group a number of ports into a broadcast domain

Higher-Layer Switches

Switch capable of interpreting Layer 3 is called a Layer 3 switch

Switch capable of interpreting Layer 4 is called a Layer 4 switch

Higher-layer switches may also be called routing switches or application switches

Routers Routers connect two or

more networks Consist of hardware and

software– Hardware

• Network server, separate computer, special black box

• Physical interface for various networks

– Software • Operating system and Routing

protocol

Routers operated at the Network layer

Routers Can connect dissimilar LANs and WANs

running at different transmission speeds and using a variety of protocols

Read the network address information in a packet

Calculates the optimal path to a particular network– Reroute packets if a path is not available

Routing tables stored in the router list all known addresses and possible paths

How do Routers Select Routes

Dynamic route selection– Routers continually adjusts the routes based on

network conditions

Static route selection– Route is designated in a table and router cannot

vary from that route

Router Features and Functions

Filter out broadcast transmission to alleviate network congestion

Prevent certain types of traffic from getting to a network

Provide high network fault tolerance through redundant components

Monitor network traffic and report statistics to a MIB Diagnose internal or other connectivity problems and

trigger alarms

Routers

Routing Protocols

Means by which routers communicate with each other about network status Routing protocol characteristics

– Convergence time• The time it takes for a router to recognize a best path in the event of a change or outage

– Bandwidth overhead• Burden placed on an underlying network to support the routing protocol

Routing Protocols

RIP (Routing Information Protocol) for IP and IPX

OSPF (Open Shortest Path First) for IP– Best path refers to the most efficient route from one

node on a network to another

EIGRP (Enhanced Interior Gateway Routing Protocol) for IP, IPX, and AppleTalk

BGP (Border Gateway Protocol) for IP

Brouters and Routing Switches

Bridge router– Also called a brouter– Industry term used to describe routers that take

on some characteristics of bridges

Routing switch– Another term for a Layer 3 or Layer 4 switch

Gateways

Combination of networking hardware and software that connects two dissimilar kinds of networks– E-mail gateway

– IBM host gateway

– Internet gateway

– LAN gateway