S305 – Network Infrastructure

Chapter 6

Local Area Network

Announcements and OutlineSubnetting ReviewCIDR NotationNumber of SubnetsNumber of Hosts

OutlineLAN/WLAN ComponentsTraditional Ethernet (IEEE 802.3)Switched EthernetWireless LANBest Practices Improving Performance

2Copyright 2010 John Wiley & Sons, Inc

Why Use a LAN?

Information sharing

Resource sharing

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Network Types

Dedicated server network • Permanently assigned a specific task • May form a powerful enterprise network replacing

mainframes• Runs a server network operating system (NOS) (Windows

2008)• Common Servers: web, email, print

Peer-to-peer network• Having hardware devices shared by all users (printers,

internet)• All computers act as both clients and servers• Results in reduced costs

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Basic LAN/WLAN Components

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Component - Network Interface Cards (NICs)

Also called network cards and network adapters

Mostly built into motherboards today

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Component - Hubs & Switches

Act as junction boxes, linking cables from several computers on a network

May allow connection of more than one kind of cabling, such as UTP and coax.

Repeater (reconstruct and strengthen) incoming signals

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Component - Network Cables

Used to connect a computer physically to the network

Types of cables Unsheilded wire pairs (UTP) – leading LAN cable type Shielded twisted pair (STP) Optical fiber – high capacity, just beginning in LANs

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1.       

Ethernet Media Types

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Planning for LAN Installations

Critically important with today’s LAN explosions

Cheapest point to install the cable?

Wiring Closets

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Wiring Closets

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Wiring Closets

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Component – Software

Software that controls the LAN

Parts of Network Operating System Server version of NOS

• Runs on the network servers Client version of NOS

• Runs on the client computers Network Profiles

• Indicate the resources available in the network and authorized users

Directory Service• Provide information about resources on the LAN

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Traditional Ethernet (IEEE 802.3) - Wired

Used by almost all LANs today

Originally developed by a consortium of Digital Equipment Corp., Intel and Xerox

Standardized as IEEE 802.3

Types of Ethernet:•

•

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Switched Ethernet

Uses workgroup switches • • •

Logical and physical topology of the network becomes a star topology via switch

Switch reads destination address of the frame and only sends it to the corresponding port

How does a hub handle frames?

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Forwarding Tables

What happens when a frame is received?

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Performance Comparison – Hub vs. Switch

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Media Access Control (MAC)

Uses a contention-based protocol called CSMA/CD (Carrier Sense Multiple Access / Collision Detect)

Frames can be sent by two computers on the same network at the same time

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CSMA/CD

Carrier Sense (CS):

Multiple Access (MA):

Collision Detect (CD):

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Best Practice Recommendations - LAN

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Improving LAN Performance

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Identifying Network Bottlenecks

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Improving Network Server Performance

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Improving Network Circuit Capacity

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Network Segmentation

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Reducing Network Demand