Download Exploring the network

Chapter 4
Intro to Routing & Switching
 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
 What
data?
does the data link layer do to help send
 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?
4.1.1
 Connect

wired or wirelessly
Switch, WAP, or ISR
 How

NIC
 How

do you connect to a wired network?
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)
4.1.2
 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
 Identify
network devices & cabling
4.1.3
 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 code
Volts/no volts; short pulse of light/long; type of
radio wave
Random timing between signals (Asynchronous)
or set time (clock) between signals (synchronous)
 Speed/capacity
a media can handle
 Like size of a hose

Bigger hose= more water through it
 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
 The
measure of usable data transferred over
a given period of time.


Throughput - traffic overhead
Example:



Ethernet is 100Mbps
Throughput is 85Mbps
If traffic overhead is 15Mbps, then goodput is 70Mbps
 What’s





the difference?
Type of copper cabling
Bandwidth it can handle
Type of connectors used
Wiring order & colors
Max distance
 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 recognized
Distinguishes data from control bits
Tells where frame starts and ends
 An

asynchronous signal means what?
No clock signal sent
 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
4.2.1
 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
 UTP,
STP, Coaxial
 Most
common
 RJ-45 connectors
 8 wires, 4 twisted pairs

Twisting prevents crosstalk
 Color
coded
 Better
EMI/RFI protection
 More expensive to buy & install
 RJ-45
 8 wires, 4 twisted pair wrapped in foil
 Used


in very early Ethernet & now for TV
Wireless antenna connections
Cable Internet
 Shielding
 Thicker
cable
 BNC or F-connector
 Flammable
 Electrical
hazard; attracts lightning
 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
 Excessively
long cable runs cause what
problem?

Attenuation, signal gets weaker
 What

is the solution to prevent crosstalk?
Twisting of the pairs
 Which

STP & coaxial
 What

cables have shielding?
RJ45
kind of connector is on UTP & STP?
4.2.1
 What


does the twisting do?
No shielding so it relies on cancellation
Wires are paired for this & twisted a certain
distance apart
 RJ45
connector
 Cat

3, 5/5e, 6
Based on bandwidth rates
 Straight-through

We’re going to make them
 Crossover

We’re going to make them
 Rollover


(Cisco’s)
Connect to console port
568B to reverse
 TIA/EIA
568A & 568B
 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
 568B to 568B

White-Orange
 Orange
 White-Green
 Blue
 White-Blue
 Green
 White-Brown
 Brown

 568A
to 568B
 Like Devices




Switch/hub port to switch/hub port
Router port to router port
PC to router port
PC to PC
Crossover
 568B to 568A
 Change Oranges & Greens on
ONE SIDE!

White-Green
 Green
 White-Orange
 Blue
 White-Blue
 Orange
 White-Brown
 Brown

 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

Goes between same devices?


Crossover
Goes from PC to switch?


cable…
Straight through
Goes from serial to console port?

Rollover
 What
colors do you change for a crossover
cable?

Oranges & greens
 What

1&2
 What

pairs transmit?
pairs receive?
3&6
4.2.3
 Transmits

pulses of light
Laser or LED
 Used
for long distance
 Glass or plastic

No EMI/RFI; no lightning attraction
 High


2

speed
LAN backbone
Connect ISP to Internet
fibers cables used
Transmit & receive
 Multimode



LED
Many paths of light
Used in LANs/Campuses


2000 meters
Less $, used more
 Single



Laser light
Single path of light
Connects backbone/NOCs


Mode
3000 meters
More $, faster speed
Issue
Bandwidth
Distance
Immunity to EMI/RFI
Immunity to Electrical
Hazards
Media/Connector cost
Installation Skill/Cost
Safety Precautions
UTP
Fiber Optic
 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.
 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
4.2.4
 Many




devices use wireless
Cordless Phones 2.4GHz Interference
Microwave Ovens Interference
Range
Solid Walls a problem
 Not
as fast as, or reliable as, wired
 Security

Wireless is east to access & can be intercepted

Authentication & Encryption now used
 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
 1999
 2.4GHz
 11Mbps
 150ft
range indoors
 300 ft range
outdoors
 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
 2003
 2.4GHz
 54Mbps
 150ft
range indoors
 300 ft range outdoors
 Compatible with 802.11b
 2.4Ghz
 100-600Mbps
 Up
to 750ft range
 Backwards compatible b/g
 Access

Point (AP)
Connects wireless devices to wired network
 Wireless

NIC adapter
Gives wireless to a host
Standard
802.11a
802.11b
802.11g
802.11n
802.11ac
Maximum
Speed
Frequency
Backwards
compatible
 Maybe???
 Doesn’t
really show wireless
 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
 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
4.3.1
 TCP/IP
 Data



equivalent?
link layer jobs:
Takes layer 3 packets & encapsulates into frames
Controls access to the media/encapsulates for
the media being used
MAC addressing

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

 Encapsulates


data into a frame
Adds frame header & trailer
Signifies beginning and end of packet
 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
 What
signifies the beginning & end of a
frame?

Header & trailer
 Which
sublayer identifies the network
protocol being used?

LLC
4.4.1
 Rules
of the rode way
 Depends


on:
Topology
Media sharing


Point-to-point WAN connection (between 2 routers)
Shared connection (LAN)
 Full
duplex
 Half duplex

Either all complete for the line or take turns


CSMA/CD (ETHERNET)



Listen for silence, transmit
Collision= all backoff random time, listen for silence,
retransmit
CSMA/CA (WIRELESS)


This is MAC (Media Access Control) at Layer 2
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

 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
4.4.4
 How

is the FCS helpful in a frame?
Determines if there are errors
 What

Start frame & MAC addresses
 The

is in the frame header?
data in a frame can be how many bytes?
46-1500 bytes
 Complete
 Take
the study guide handout
the quiz on netacad.com
 Jeopardy
review
In this chapter, you learned:
 Devices
Chapter 4
Intro to Routing & Switching