Chapter 2 - TechnologyProServices

prunelimitNetworking and Communications

Oct 23, 2013 (3 years and 9 months ago)

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Chapter 2


The TCP/IP and OSI Networking Models


Networking architecture


An organized set of documents.


Describe one small function required for a network.


Protocol


a set of logical rules that devices must follow to
communicate.


Chapter Goal


Understand networking model and how it works

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Go through the Quiz
-

5 minutes

1.
Which of the following protocols are examples of
TCP/IP transport layer protocols?

a.
Ethernet

b.
HTTP

c.
IP

d.
UDP

e.
SMTP

f.
TCP



1.
Which of the following protocols are examples of
TCP/IP transport layer protocols?

a.
Ethernet

b.
HTTP

c.
IP

d.
UDP

e.
SMTP

f.
TCP

Answer: D & F

2.
Which of the following protocols are examples of TCP/IP
network access layer protocols?

a.
Ethernet

b.
HTTP

c.
IP

d.
UDP

e.
SMTP

f.
TCP

g.
PPP




2.
Which of the following protocols are examples of TCP/IP
network access layer protocols?

a.
Ethernet

b.
HTTP

c.
IP

d.
UDP

e.
SMTP

f.
TCP

g.
PPP


Answer: A &G

3.
The process of HTTP asking TCP to send
some data and make sure that it is
received correctly is an example of what?

a.
Same
-
layer interaction

b.
Adjacent
-
layer interaction

c.
The OSI model

d.
All the other answers are correct.



3.
The process of HTTP asking TCP to send
some data and make sure that it is
received correctly is an example of what?

a.
Same
-
layer interaction

b.
Adjacent
-
layer interaction

c.
The OSI model

d.
All the other answers are correct.

Answer: B

4.
The process of TCP on one computer marking a
segment as segment 1, and the receiving
computer then acknowledging the receipt of
segment 1, is an example of what?

a.
Data encapsulation

b.
Same
-
layer interaction

c.
Adjacent
-
layer interaction

d.
The OSI model

e.
None of these answers are correct.




4.
The process of TCP on one computer marking a
segment as segment 1, and the receiving
computer then acknowledging the receipt of
segment 1, is an example of what?

a.
Data encapsulation

b.
Same
-
layer interaction

c.
Adjacent
-
layer interaction

d.
The OSI model

e.
None of these answers are correct.

Answer: B


5.
The process of a web server adding a
TCP header to a web page, followed by
adding an IP header, and then a data link
header and trailer is an example of what?

a.
Data encapsulation

b.
Same
-
layer interaction

c.
The OSI model

d.
All of these answers are correct.



5.
The process of a web server adding a
TCP header to a web page, followed by
adding an IP header, and then a data link
header and trailer is an example of what?

a.
Data encapsulation

b.
Same
-
layer interaction

c.
The OSI model

d.
All of these answers are correct.

Answer: A

6.
Which of the following terms is used specifically to
identify the entity that is created when encapsulating
data inside data link layer headers and trailers?

a.
Data

b.
Chunk

c.
Segment

d.
Frame

e.
Packet

f.
None of these

there is no encapsulation by the data link
layer.



6.
Which of the following terms is used specifically to
identify the entity that is created when encapsulating
data inside data link layer headers and trailers?

a.
Data

b.
Chunk

c.
Segment

d.
Frame

e.
Packet

f.
None of these

there is no encapsulation by the data link
layer.

Answer: D


7.
Which OSI layer defines the functions of logical
network
-
wide addressing and routing?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7



7.
Which OSI layer defines the functions of logical
network
-
wide addressing and routing?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7

Answer: C

8.
Which OSI layer defines the standards for
cabling and connectors?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7



8.
Which OSI layer defines the standards for
cabling and connectors?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7

Answer: A

9.
Which OSI layer defines the standards for data
formats and encryption?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7



9.
Which OSI layer defines the standards for data
formats and encryption?

a.
Layer 1

b.
Layer 2

c.
Layer 3

d.
Layer 4

e.
Layer 5

f.
Layer 6

g.
Layer 7

Answer: F

10.
Which of the following terms are not valid
terms for the names of the seven OSI layers?

a.
Application

b.
Data link

c.
Transmission

d.
Presentation

e.
Internet

f.
Session



10.
Which of the following terms are not valid
terms for the names of the seven OSI layers?

a.
Application

b.
Data link

c.
Transmission

d.
Presentation

e.
Internet

f.
Session

Answer: C & E

Any Questions?

Foundation Topics


TCP/IP is most widely supported protocol


Early Protocols were owned by the company
that wrote them


Each vendor had different network. Interoperability
was difficult


ISO organized to write a standard in the late
1970’s


DARPA also started a standard


TCP/IP


Pg 21

The TCP/IP Protocol Architecture


Large Collection of protocols that allow
computers to communicate


Request For Comments (RFCs) defines the
protocols


http://www.ietf.org/rfc.html


Standard provide interoperability


Can any phone into the phone network


Computer with TCP/IP will work on almost nay
data network

Pg 22

TCP/IP Architecture

Pg 22

The TCP/IP Application Layer


Defines services for an application


Capability to transfer a file


Provides interface between software and
network


Pg 23

Application Layer Example


HTTP Request
-
HTTP transfer of file


HTML is the Language of the file being
transferred


Pg 23

More Details on Example


Request


HTTP Header
-
Get home.htm


Reply


HTTP OK
-
Sends contents


HTTP Headers have codes


200
-
File Found


404
-
File not found

Pg 24

More Details on Example


When a layer of the TCP/IP Architecture want to
communicate it uses the headers to communicate with
the SAME layer on the other machine


Same
-
layer interaction



Application Layer doesn’t define the application used on
the computer


Defines how to accomplish the networking tasks that the
application wants


File transfers, etc.


Pg 24

Any Questions?

The TCP/IP Transport Layer


Two main Protocols


Transmission Control Protocol (TCP)


Provides error recovery by providing
acknowledgements


User Datagram Protocol (UDP)


Provides Service to Application Layer


Helps provide services to the transport of
application layer information (files and
requests)


Pg 25

Reliability by TCP


TCP headers manage the flow of data


If data is lost, TCP resends the data


Adjacent
-
layer interaction

Pg 26

Reliability by TCP


Application and Transport Layer can ignore lower layers


Work the same way regardless of whether the computers are
communicating on a LAN or over the Internet


Lower layers deal with the physical network

Pg 27

Any Questions?

The TCP/IP Internet Layer


Is there a difference to you when you send
a letter to a local friend or to another city?


Local Letter


Goes to your Post Office and then to friend


Another City


Goes to your post office, then to main post
office, then to main post office in other city,
then to friend’s post office, then to friend


Pg 27

The TCP/IP Internet Layer


Internet Layer Defines


IP Addressing


Unique addressing for each host computer


IP Routing


So that routers can make decisions on where to
send the packets of data

Pg 27

Internet Layer in Action


IP Packet


IP Header


TCP Header


Application Header


Application Data (none in this case)

Pg 28

Internet Layer in Action


Bob Sends packet to router R2


R2 examines destination IP address


R2 makes routing decision based on
known topology


Knows that Larry must be on other side of R1


R1 passes the packet to Larry

Pg 28

Any Questions?

The TCP/IP Network Access Layer


Defines protocols and hardware for
delivering data across physical networks


Defines physical connection to the network
media over which data can be transmitted


Provides services to the layer above it


Example
-
Ethernet


Cabling, addressing and protocols for an
Ethernet LAN

Pg 28

The TCP/IP Network Access Layer


Internet Layer doesn’t know how to use
wires


Network Access services Internet Layer by
providing link to numerous physical
implentations


Ethernet and Other LAN standards


PPP, Frame
-
Relay and other WAN
standards

Pg 29

Network Access Layer
-
In action


Bob sends IP packet to R2


Wraps IP packet in Ethernet Header and Trailer
-
an
Ethernet
FRAME


R2 doesn’t need Ethernet Header and Trailer


Strips them off and has IP packets


Puts a PPP header and Trailer around it
-
PPP FRAME


R1 does the same strip of PPP information and
adds new Ethernet information

Pg 29

Network Access Layer
-
In action


People often think of Network Access layer as
two parts


Network layer


Physical layer


Not part of specification, but can be handled
differently

Pg 29

Any Questions?

Data Encapsulation Terminology


Each layer adds its own header and
possibly trailer


Encapsulation


Application Layer


Encpasulates web page with HTTP header


Transport Layer


Encpasulated HTTP header and data in TCP
header


Etc

Pg 30

Data Encapsulation Terminology


Step 1 Create and encapsulate the application data with any
required application layer headers.
For example, the HTTP OK
message can be returned in an HTTP header, followed by part of
the contents of a web page.


Step 2 Encapsulate the data supplied by the application layer
inside a transport layer header.
For end
-
user applications, a TCP
or UDP header is typically used.


Step 3 Encapsulate the data supplied by the transport layer
inside an internet layer (IP) header.
IP is the only protocol
available in the TCP/IP network model.


Step 4 Encapsulate the data supplied by the internet layer
inside a network access layer header and trailer.
This is the only
layer that uses both a header and a trailer.


Step 5 Transmit the bits
. The physical layer encodes a signal onto
the medium to transmit the frame.

Pg 30

Data Encapsulation Terminology

Pg 31

Any Questions?

The OSI Reference Model


Never really used in real world


Still a reference point for layered protocols


Need to know OSI terminology


Easily compared to TCP/IP model

Pg 32

Comparing OSI and TCP/IP

Pg 33

OSI and TCP/IP


OSI Network Layer is like TCP/IP Internet Layer
-
why?


Defines logical addressing


Defines routing


TCP/IP Transport layer defines error recovery
-
like OSI
Transport layer


TCP is called Layer 4 protocol

Pg 33

OSI Layers and Their Functions


Many devices actually understand protocols at
multiple layers, but highest is mentioned.

Pg 35

Memorizing the OSI Layer


All People Seem To Need Data Processing


Please Do Not Throw Sausage Pizza Away

Pg 35

OSI Layering Concepts and Benefits


Less Complex


Compared to not using a model, network models break
the concepts into smaller parts.


Standard Interfaces


The standard interface definitions between each
layer allow for multiple vendors to create products that compete to be used
for a given function, along with all the benefits of open competition.


Easier to learn


Humans can more easily discuss and learn about the
many details of a protocol specification.


Easier to develop


Reduced complexity allows easier program changes
and faster product development.


Multivendor interoperability


Creating products to meet the same
networking standards means that computers and networking gear from
multiple vendors can work in the same network.


Modular engineering


One vendor can write software that implements
higher layers

for example, a web browser

and another vendor can write
software that implements the lower layers

for example, Microsoft’s built
-
in
TCP/IP software in its operating systems.

Pg 36

OSI Encapsulation Terminology


Same process of adding headers and possible
trailers to previous layer


Rather than Segment, packet, frame


Protocol Data Unit

Pg 37

Any Questions?

Chapter Key topics



See CD in back of book for additional printable
appendices


Appendix H
-
Memory Tables

Pg 38

Any Questions?