NETWORK ACCESS

Chapter 4

Intro to Routing & Switching

OBJECTIVES Upon completion of this chapter, you

should be able to: Describe the purpose of the physical layer Identify characteristics of copper cabling Make a UTP cable Describe fiber optic cabling & its advantages Describe wireless media Select the appropriate media to connect

devices Describe the data link layer, its purpose &

structure of a frame Compare logical & physical topologies Describe media access control

PHYSICAL & DATA LINK LAYERS What does the data link layer do to help

send data?

What does the physical layer do to help send the data?

What does the physical layer do to help receive data?

What does the data link layer do to help receive data?

GETTING IT CONNECTED

4.1.1

CONNECTING TO THE NETWORK Connect wired or wirelessly

Switch, WAP, or ISR

NETWORK INTERFACE CARDS How do you connect to a wired network?

NIC

How do you connect to a wireless network?WLAN NIC

What are disadvantages of wireless?Distance from WAP (can use extender)Sharing of wireless signal (more=slower)

PURPOSE OF THE PHYSICAL LAYER

4.1.2

OSI & COMMUNICATION

MEDIA Copper

Electrical pulses Fiber

Light Wireless

Radio waves

All follow standards so they can communicate together ISO (RJ-45), EIA/TIA (568B), IEEE (802.3,

802.11), and others

LAB 4.1.2.4 Identify network devices & cabling

REVIEW

REVIEW

FUNDAMENTAL PRINCIPLES OF

LAYER 1

4.1.3

PHYSICAL LAYER Physical components

Cabling, NICs, connectors, ports/interfaces Encoding

Pattern of voltage for 1’s & 0’s Differentiates data from control bit info The patterns indicate start & end of frame

Signaling It’s what represents a 0 or 1/like Morse codeVolts/no volts; short pulse of light/long; type of

radio waveRandom timing between signals

(Asynchronous) or set time (clock) between signals (synchronous)

BANDWIDTH Speed/capacity a media can handle Like size of a hose

Bigger hose= more water through it

THROUGHPUT Measure of transfer of bits over a time

Varies on amount & type of traffic, latency (delay)

Can only be as fast as the slowest link

GOODPUT The measure of usable data transferred

over a given period of time. Throughput - traffic overheadExample:

Ethernet is 100Mbps Throughput is 85Mbps If traffic overhead is 15Mbps, then goodput is

70Mbps

TYPES OF MEDIA What’s the difference?

Type of copper cablingBandwidth it can handleType of connectors usedWiring order & colorsMax distance

ACTIVITY

REVIEW GCIT’s Ethernet is 1000Mbps. It’s

throughput is 800Mbps. If overhead is 10Mbps, what is the goodput?790Mbps

Why are encoding methods (patterns for the bits) used by the physical layer?So the code can be recognizedDistinguishes data from control bitsTells where frame starts and ends

An asynchronous signal means what?No clock signal sent

REVIEW Morse code & the timing between the

bits is known as what?Signaling

The speed or capacity of your media is what?Bandwidth

The actual amount of bits/data that can actually pass over a period of time is what?Throughput

The more bandwidth you have, the more __________________ you should have.Throughput

COPPER CABLING INTRODUCTION

4.2.1

COPPER MEDIA Inexpensive & easy to install

Look up a box of Cat 5e 500ft spool Electrical pulses Distance limit (attenuation) Interference from EMI/RFI, crosstalk

To avoid problems, select the right cable for the right situation

COPPER CABLING UTP, STP, Coaxial

UTP- QUICK OVERVIEW Most common RJ-45 connectors 8 wires, 4 twisted pairs

Twisting prevents crosstalk Color coded

STP- QUICK OVERVIEW Better EMI/RFI protection More expensive to buy & install RJ-45 8 wires, 4 twisted pair wrapped in foil

COAXIAL- QUICK OVERVIEW Used in very early Ethernet & now for TV

Wireless antenna connectionsCable Internet

Shielding Thicker cable BNC or F-connector

COPPER MEDIA SAFETY Flammable Electrical hazard; attracts lightning

ACTIVITY

REVIEW What in the ceiling could “mess up” the

electrical signal in an UTP cable?Lights, electrical boxes/equipment

Radio waves cause what kind of interference?RFI

An electrical motor near a UTP cable causes what kind of interference?EMI

Signals from one cable jump into another. What problem is this?Crosstalk

REVIEW Excessively long cable runs cause what

problem?Attenuation, signal gets weaker

What is the solution to prevent crosstalk?Twisting of the pairs

Which cables have shielding?STP & coaxial

What kind of connector is on UTP & STP?RJ45

COPPER CABLING

4.2.1

UTP What does the twisting do?

No shielding so it relies on cancellationWires are paired for this & twisted a certain

distance apart RJ45 connector

UTP Cat 3, 5/5e, 6

Based on bandwidth rates

TYPES OF UTP CABLES Straight-through

We’re going to make them Crossover

We’re going to make them Rollover (Cisco’s)

Connect to console port568B to reverse

MAKING UTP CABLES TIA/EIA 568A & 568B

STRAIGHT-THROUGH CABLE 568B to 568B Connect unlike devices

Computer to Hub/Switch Switch to router port

On the PC NIC Pins 1 & 2 transmit Pins 3 & 6 receive

STRAIGHT-THROUGH CABLE Straight-through 568B to 568B

White-Orange Orange White-Green Blue White-Blue Green White-Brown Brown

CROSSOVER CABLE 568A to 568B Like Devices

Switch/hub port to switch/hub portRouter port to router portPC to router portPC to PC

CROSSOVER CABLE Crossover 568B to 568A Change Oranges & Greens

on ONE SIDE!

White-Green Green White-Orange Blue White-Blue Orange White-Brown Brown

REVIEW What is the 568B color order?

Wor/Or, WGr/Bl, WBl/Gr, WBr/Br For speeds of 1000Mbps or more, what

Category cable should be used?Cat 6

What cable…Goes between same devices?

CrossoverGoes from PC to switch?

Straight throughGoes from serial to console port?

Rollover

REVIEW What colors do you change for a

crossover cable?Oranges & greens

What pairs transmit?1 & 2

What pairs receive?3 & 6

FIBER OPTIC CABLING

4.2.3

FIBER OPTIC Transmits pulses of light

Laser or LED Used for long distance Glass or plastic

No EMI/RFI; no lightning attraction High speed

LAN backboneConnect ISP to Internet

2 fibers cables usedTransmit & receive

FIBER OPTIC TYPES Multimode

LEDMany paths of lightUsed in LANs/Campuses

2000 meters Less $, used more

Single ModeLaser lightSingle path of lightConnects backbone/NOCs

3000 meters More $, faster speed

FIBER CONNECTORS/PATCH CABLES

ACTIVITY- USE LOW OR HIGH

Issue UTP Fiber Optic

Bandwidth

Distance

Immunity to EMI/RFI

Immunity to Electrical Hazards

Media/Connector cost

Installation Skill/Cost

Safety Precautions

ACTIVITY

REVIEW Which cable is more expensive, copper

or fiber?Fiber

Which cable allows data to travel further, copper or fiber?Fiber

Why are two strands of fiber used for communication?Light can only travel in one direction at a

time. This will allow for full-duplex.

REVIEW What signal travel on a single-mode

cable?Laser

Which cable would be used to go further distances?Single mode

Why would you use fiber between buildings rather than copper?Fiber does not attract lightning

WIRELESS MEDIA

4.2.4

WIRELESS CONCERNS Many devices use wireless

Cordless Phones 2.4GHz InterferenceMicrowave Ovens InterferenceRangeSolid Walls a problem

Not as fast as, or reliable as, wired Security

Wireless is east to access & can be intercepted Authentication & Encryption now used

WIRELESS STANDARDS Specifies data speed, range, RF

spectrum IEEE standards, Wi-Fi 802.11a, 802.11b, 802.11g and 802.11n

Wi-Fi Alliance tests devices from manufacturer

Will work with other devices w/ same logo

802.11B

1999 2.4GHz 11Mbps 150ft range

indoors 300 ft range

outdoors

802.11A 1999 5GHz

Unused at that time Less congestion

54Mbps (faster than B) NOT compatible with b/g/n 75ft-150ft range Originally too expensive Now hard to find

802.11G 2003 2.4GHz 54Mbps 150ft range indoors 300 ft range outdoors Compatible with 802.11b

802.11N 2.4Ghz 100-600Mbps Up to 750ft range Backwards compatible

b/g

WIRELESS COMPONENTS Access Point (AP)

Connects wireless devices to wired network Wireless NIC adapter

Gives wireless to a host

WIRELESS CHART

Standard Maximum Speed Frequency Backwards

compatible

802.11a

802.11b

802.11g

802.11n

802.11ac

LAB 4.2.4.5? & 4.2.4.6! Maybe??? Doesn’t really show wireless

REVIEW You’d like to add wireless with speeds up

to 1.3Gbps. Which spec should you buy?802.11ac

What is the max speed of G?54Mbps

What connects wireless devices to a wired network?AP

What wireless spec is no compatible with others?802.11a

REVIEW What could interfere with a wireless

signal?Cordless phones, microwaves, solid walls

What are 2 other concerns with wireless networks?Security and distance

802.11b, g, and n all operate on what frequency?2.4GHz

PURPOSE OF THE DATA LINK LAYER

4.3.1

DATA LINK LAYER TCP/IP equivalent?

Data link layer jobs:Takes layer 3 packets & encapsulates into

framesControls access to the media/encapsulates

for the media being usedMAC addressing

DATA LINK SUBLAYERS LLC

Closer to layer 3 Identifies what layer 3 protocol is being used

MAC Closer to layer 1; rules for accessing media MAC address Ready for convert to any type of bits/media

LAYER 2 FRAMING Encapsulates data into a frame

Adds frame header & trailerSignifies beginning and end of packet

REVIEW What layer of the OSI generates the

electrical signals?Physical layer

What layer decides the best path?Network layer

What layer handles the encapsulation for the proper media going to be used?Data link layer

What are the 2 sublayers of the Data Link layer?LLC & MAC

REVIEW What signifies the beginning & end of a

frame?Header & trailer

Which sublayer identifies the network protocol being used?LLC

TOPOLOGIES

4.4.1

MEDIA ACCESS CONTROL Rules of the rode way

Depends on:TopologyMedia sharing

Point-to-point WAN connection (between 2 routers)

Shared connection (LAN)

LAN PHYSICAL TOPOLOGIES

LOGICAL TOPOLOGY

Full duplex Half duplex

WAN TOPOLOGIES

LOGICAL TOPOLOGY & TALKING Either all complete for the line or take turns

This is MAC (Media Access Control) at Layer 2

CSMA/CD (ETHERNET) Listen for silence, transmit Collision= all backoff random time, listen for

silence, retransmit CSMA/CA (WIRELESS)

Listen for silence, notify all you are sending, gets clearance to send, transmits

Token Passing (OLD for Token Ring/FDDI) Wait for your turn/have the token Logical ring topology

REVIEW Ethernet’s collision detection system is

known as what?CSMA/CD

Describe CSMA/CD. 802.11 wireless networks use what for

avoiding collisions?CSMA/CA

What is the main difference between CSMA/CA & CD?CA notifies all that you are sending

THE FRAME

4.4.4

FRAME

FRAME SIZE

PROJECT

REVIEW How is the FCS helpful in a frame?

Determines if there are errors

What is in the frame header?Start frame & MAC addresses

The data in a frame can be how many bytes?46-1500 bytes

REVIEW & STUDY Complete the study guide handout

Take the quiz on netacad.com

Jeopardy review

SUMMARYIn this chapter, you learned: Devices

SUMMARY

SUMMARY

NETWORK ACCESS

Chapter 4

Intro to Routing & Switching