CCNA RS_ITN - Chapter 3

Chapter 3:
Network Protocols and
Communications
Introduction to Networks
© 2008 Cisco Systems, Inc. All Presentation_ID rights reserved. Cisco Confidential 1

Chapter 3: Objectives
Students will be able to:
 Explain how rules are used to facilitate communication.
 Explain the role of protocols and standards
organizations in facilitating interoperability in network
communications.
 Explain how devices on a LAN access resources in a
small to medium-sized business network.
Presentation_ID © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential 2

Chapter 3
3.1 Rules of Communication
3.2 Network Protocols and Standards
3.3 Moving Data in the Network
3.4 Summary

The Rules
What is Communication?

The Rules
Establishing the Rules
Establishing the Rules
 An identified sender and receiver
 Agreed upon method of communicating (face-to-face,
telephone, letter, photograph)
 Common language and grammar
 Speed and timing of delivery
 Confirmation or acknowledgement requirements

The Rules
Message Encoding

The Rules
Message Formatting and Encapsulation
Example: Personal letter contains the following elements:
 An identifier of the recipient
 A salutation or greeting
 The message content
 A closing phrase
 An identifier of the sender

The Rules
Message Size
The size restrictions of frames require the source host to break
a long message into individual pieces that meet both the
minimum and maximum size requirements.
This is known as segmenting.
Each segment is encapsulated in a separate frame with the
address information, and is sent over the network.
At the receiving host, the messages are de-encapsulated and
put back together to be processed and interpreted.

The Rules
Message Timing
 Access Method
 Flow Control
 Response Timeout

The Rules
Message Delivery Options

Protocols
Rules that Govern Communications

Protocols
Network Protocols
 How the message is formatted or structured
 The process by which networking devices share information
about pathways with other networks
 How and when error and system messages are passed
between devices
 The setup and termination of data transfer sessions

Protocols
Interaction of Protocols
 Application Protocol – Hypertext Transfer Protocol (HTTP)
 Transport Protocol – Transmission Control Protocol (TCP)
 Internet Protocol – Internet Protocol (IP)
 Network Access Protocols – Data Link & Physical layers

Protocol Suites
Protocol Suites and Industry Standards

Protocol Suites
Creation of Internet, Development of TCP/IP

Protocol Suites
TCP/IP Protocol Suite and Communication

Network Protocols and Standards
Standards Organizations

Open Standards
 The Internet Society (ISOC)
 The Internet Architecture Board (IAB)
 The Internet Engineering Task Force (IETF)
 Institute of Electrical and Electronics Engineers (IEEE)
 The International Organization for Standards (ISO)

ISOC, IAB, and IETF

IEEE
 38 societies
 130 journals
 1,300 conferences each year
 1,300 standards and projects
 400,000 members
 160 countries
 IEEE 802.3
 IEEE 802.11

ISO

Other Standards Organization
 The Electronic Industries Alliance (EIA)
 The Telecommunications Industry Association (TIA)
 The International Telecommunications Union –
Telecommunications Standardization Sector (ITU-T)
 The Internet Corporation for Assigned Names and Numbers
(ICANN)
 The Internet Assigned Numbers Authority (IANA)

Reference Models
The Benefits of Using a Layered Model

Reference Models
The OSI Reference Model

Reference Models
The TCP/IP Reference Model

Reference Models
Comparing the OSI and TCP/IP Models

Data Encapsulation
Communicating the Messages
 Segmenting message benefits
Different conversations can be interleaved
Increased reliability of network communications
 Segmenting message disadvantage
Increased level of complexity

Data Encapsulation
Protocol Data Units (PDUs)
 Data
 Segment
 Packet
 Frame
 Bits

Data Encapsulation
Encapsulation

Data Encapsulation
De-encapsulation

Moving Data in the Network
Accessing Local Resources

Network Addresses & Data Link addresses
 Network Address
Source IP address
Destination IP address
 Data Link Address
Source data link address
Destination data link address

Communicating with Device / Same Network

MAC and IP Addresses
PC1
192.168.1.110
AA-AA-AA-AA-AA-AA
PC2
192.168.1.111
BB-BB-BB-BB-BB-BB
11-11-11-11-11-11
S1 R1
FTP Server
192.168.1.9
R1
192.168.1.1
CC-CC-CC-CC-CC-CC
ARP
Request

Accessing Remote Resources
Default Gateway
PC 1
192.168.1.110
AA-AA-AA-AA-AA-AA
PC 2
192.168.1.111
BB-BB-BB-BB-BB-BB
R1
192.168.1.1
11-11-11-11-11-11
FTP Server
192.168.1.9
CC-CC-CC-CC-CC-CC
R2
172.16.1.99
22-22-22-22-22-22
Web Server
172.16.1.99
AB-CD-EF-12-34-56

Communicating Device / Remote Network

Using Wireshark to View Network Traffic

Network Protocols and Communications
Summary
In this chapter, you learned:
 Data networks are systems of end devices, intermediary
devices, and the media connecting the devices. For
communication to occur, these devices must know how to
communicate.
 These devices must comply with communication rules and
protocols. TCP/IP is an example of a protocol suite.
 Most protocols are created by a standards organization such
as the IETF or IEEE.
 The most widely-used networking models are the OSI and
TCP/IP models.

Summary
 Data that passes down the stack of the OSI model is
segmented into pieces and encapsulated with addresses and
other labels. The process is reversed as the pieces are de-encapsulated
and passed up the destination protocol stack.
 The OSI model describes the processes of encoding,
formatting, segmenting, and encapsulating data for
transmission over the network.
 The TCP/IP protocol suite is an open standard protocol that
has been endorsed by the networking industry and ratified, or
approved, by a standards organization.

Summary
 The Internet Protocol Suite is a suite of protocols required for
transmitting and receiving information using the Internet.
 Protocol Data Units (PDUs) are named according to the
protocols of the TCP/IP suite: data, segment, packet, frame,
and bits.
 Applying models allows individuals, companies, and trade
associations to analyze current networks and plan the
networks of the future.

CCNA RS_ITN - Chapter 3

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