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
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