Transcript DOCSIS Basics CBT - Bryan Walhovd

University of Wisconsin Stout
Learning Technologies
Bryan Walhovd
DOCSIS CABLE MODEM BASICS
Goals:
 The Goal of this Module is to give you a basic understanding of a
cable modem and how it operates.
 This high level overview will help you understand the following:





What a cable modem is.
The types of interfaces that exist on the modem.
Devices associated with a cable provider network.
How a modem comes online.
Glance into the OSI model and DOCSIS.
 Future modules will provide a detailed view of each step a modem
takes to come online as well as factors that limit connectivity and
speed.
What is a Cable modem?
 A cable modem is a broadband device used to connect to
the internet over a cable companies Hybrid Fiber Coaxial
Network (HFC).
Image courtesy of:
https://daiswiki.wikispaces.com/
Cable modem interface
 A cable modem has two main interfaces that allow
operation with the cable plant and customer equipment.
 A coaxial cable port used to hook up to the cable plant
Image courtesy of:
http://www.cloudclipart.com/clipart/otherclipart/coaxial-cable-detail
 A RJ45 port which is used to connect to a computer or
router via an RJ45 Ethernet cable.
Image courtesy of:
http://www.cloudclipart.com/clipart/freeclipart/rj45-detail
In your home
 Typically a modem is hooked to a router in a home or a
business which allows access too the internet for
multiple devices including PC’s, Phones, Printers and
Gaming consoles.
Image courtesy of:
bmisitgs.wikispaces.com
Connection
 Once the cable modem is connected to the HFC plant via
the Coaxial connector and your PC, your all ready to go
right?
 Not exactly! The modem itself has to be set up
(provisioned) on the cable providers network in order for
it to access the internet.
 So what next?
The Cable Modem Termination
System
 Once hooked up to the coaxial plant, the modem
connects back to the cable providers CMTS, located
typically in a HeadEnd.
Image courtesy of: By Vivien Guéant [CC BY-SA 3.0
(http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
What does all this mean???
 A Modulator Demodulator (modem) communicates with
the cable provider utilizing Radio Frequency.
 This communication is bi-directional as we send and
receive data from our personal devices.
Images courtesy of:
http://www.cloudclipart.com/clipart/free-clipart
Image courtesy of:
https://daiswiki.wikispaces.com/
Image courtesy of: By Vivien
Guéant [CC BY-SA 3.0
(http://creativecommons.org/licens
es/by-sa/3.0)], via Wikimedia
Commons
How it works!
Downstream Lock
 The modem first locks onto the Downstream
frequency(s). The normal frequency range delivered from
the cable provider is 54Mhz to 1000 Mhz.
Power
Modem ON
Scan for Downstream Channel
Downstream Sync Established
Upstream Lock
 The CMTS then sends a UCD (Upstream
Channel Descriptor) which tells the modem
the Return frequency to talk back at which is
typically 5Mhz to 42Mhz.
Obtain the upstream parameters
UCD acquired
Ranging and IP
 Once the modem has successfully locked on
downstream and upstream, it completes ranging, IP
connectivity, and security.
Start Ranging
IP Complete
Complete Ranging and Power
adjustments
Establish TOD/TOD Established
Establish IP Connectivity
Establish Security/ Security
Established
Configuration, Registration
and Baseline Privacy.
 Almost there!!
Transfer operational parameters
and configuration file.
Initiate and establish Baseline
Privacy
Register with CMTS
Modem is
operational!
Registration complete
I’m ONLINE!!
 Your device can now communicate to the internet!!!
Image courtesy of:
http://lis3353.wikispaces.com/file/view/125_systemy_standardu_docsis.jpg/89183273/332x209/125_syste
my_standardu_docsis.jpg
Do all cable modems function
the same?
 The OSI model was defined to standardize the functions
of a communication system.
 A cable modem, as with most communication devices,
uses the Open Systems Interconnection Model.
 The OSI model breaks a communication system into
different layers with the objective of interoperability
between devices without requiring logic changes of
hardware and software.
Open System Interconnection?
Detail:
•Each Layer is
briefly described in
the included
diagram.
• Where do you
think DOCSIS
modems operate?
Image By Dino.korah [GFDL
(http://www.gnu.org/copyleft/fdl.html) or
CC-BY-SA-3.0
(http://creativecommons.org/licenses/bysa/3.0/)], via Wikimedia Commons
OSI and DOCSIS
 Data Over Cable Service Interface Specification (DOCSIS)
was designed to standardize high bandwidth data
transfer between cable providers internationally.
 DOCSIS standard changes as the consumer demand for
bandwidth increases.
 DOCSIS modems operate primarily at the Physical, Data
Link and Network layers of the OSI model.
Quiz
What do you know about
DOCSIS cable modems??
Click Here to start the Quiz
Hint: Pick the best answer!
A cable modem is a broadband
device used to connect to
the internet over which type
of Network?
Fiber Network
Coaxial Cable Network
HFC Network
Wireless Network
CORRECT!!
Next Question
Please Try Again!!
Try Again
Next Question
OSI is short for?
Open System
Interconnection
Open System Interface
Open Something
Interesting
Open System Internet
Try This one!
CORRECT!!
Next Question
Please Try Again!!
Try Again
Next Question
CMTS stands for?
Cable Modem
Television system
Cable Modem
Telecommunications
System
Cable Modem
Transitional System
Cable Modem
Termination System
CORRECT!!
Next Question
Please Try Again!!
Try Again
Next Question
The first thing a modem does
when hooked to the HFC
network once powered on is?
Looks for it’s upstream
parameters
Registers with the
CMTS
Looks for its
Downstream
Accesses the internet
CORRECT!!
Great Job!! Quiz
Complete
Please Try Again!!
Try Again
Great Job!! Quiz
Complete
Thank You for Completing
DOCSIS Cable Modem Basics Part
1.
If you have additional questions or feedback,
please click here.
Cable Modems are
interesting…
Try Again