Exploring the network
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Transcript 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