© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential Presentation_ID 1

Chapter 3: Network Protocols and Communications

Introduction to Networks

Presentation_ID 2 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Chapter 3: Objectives

After completing this chapter, you 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 3 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

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

Presentation_ID 4 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

The Rules What is Communication? Communication is exchange of information through a medium.

Presentation_ID 5 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Rules for Communication There must be a sender and receiver

Method of communicating must be agreed, eg - face-to-face, - telephone, - letter, - photograph, etc.

There must be common language and grammar

Speed and timing of delivery must be specified

Confirmation or acknowledgment requirements must be decided on

Presentation_ID 6 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Machine Communication

Presentation_ID 7 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Formatting and Encapsulation

Before being sent, a message must be formatted and encapsulated.

Encapsulation means binding together the data and functions that manipulate the data, and keeping them safe from outside interference and misuse.

Presentation_ID 8 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Formatting and Encapsulation A message can contain the following elements:

Identifier of the recipient’s location (where)

Identifier of the sender’s location (where)

Salutation or greeting (“Hello”)

Recipient identifier (“Peter”)

The message content (“How are you”)

Source identifier

End of message indicator

Presentation_ID 9 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Size, segment, frame An overview of the segmenting process:

A message has a minimum and maximum size.

A message is broken into segments.

Each segment is encapsulated in a separate frame with the address information. The size of one frame is usually limited.

The frames are sent to the receiving host.

At the receiving host, each frame is de-encapsulated and put back together as a message. It is then processed and interpreted.

Presentation_ID 10 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

The Rules Message Sending process A message is broken into segments.

Each segment is encapsulated in a separate frame with the address information, and is sent over the network.

At the receiving host, the message is de-encapsulated and put back together to be processed and interpreted.

Presentation_ID 11 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Timing Access Method Managing data on a network is a form of data traffic control.

The set of rules that governs how network traffic is controlled is called the access method.

Access Method determines when it is ready for a computer to send a message to avoid a collision of information.

It is necessary for computers to define an access method.

Hosts on a network need an access method to know when to begin sending messages and how to respond when errors occur.

Presentation_ID 12 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Timing Flow Control

Source and destination hosts use flow control to, - negotiate correct timing for successful communication - determine the amount of data to send, - determine the speed of sending.

Presentation_ID 13 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Timing Response Timeout

When a message is sent, it can be received successfully.

But sometimes, the receiver may take too long to do so. A time duration for timeout needs to be set. This is known as Response Timeout.

Hosts on the network have rules that specify, - how long to wait for responses; after a pre-set time, the hosts will stop trying and issue a response timeout message - what action to take if a response timeout occurs.

Presentation_ID 14 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Message Delivery Options 3 ways of sending messages are:

• Unicast (one-to-one) Unicast is communication between a single sender and a single receiver over a network.

• Multicast (one-to-many) Multicast is communication between a single sender and many interested receivers over a network.

• Broadcast (one-to-all) Broadcast is communication between a single sender and ALL devices in a network.

© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential Presentation_ID 15

3.2 Network Protocols and Standards

Presentation_ID 16 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocols Rules that Govern Communications

Presentation_ID 17 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocols Network Protocols

Communication in networks also need rules to govern:

Message format or structure

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

Presentation_ID 18 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocols 4 Layers 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

Presentation_ID 19 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocol Suites TCP/IP Protocol Suite and Communication

Presentation_ID 20 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocol Suites Protocol Suites and Industry Standards

Four protocol suites used in the Industry are: • TCP/IP • ISO • Apple Talk • Novell Netware

Presentation_ID 21 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocol Suites Creation of Internet, Development of TCP/IP The first packet switching network and predecessor to today’s Internet

was the Advanced Research Projects Agency Network (ARPANET), which came to life in 1969 by connecting mainframe computers at four locations.

ARPANET was funded by the U.S. Department of Defense for use by universities and research laboratories. Bolt, Beranek and Newman (BBN) was the contractor that did much of the initial development of the ARPANET, including creating the first router known as an Interface Message Processor (IMP).

Presentation_ID 22 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Protocol Suites Creation of Internet, Development of TCP/IP In 1973, Robert Kahn and Vinton Cerf began work on TCP to develop the

next generation of the ARPANET. TCP was designed to replace ARPANET’s current Network Control Program (NCP).

In 1978, TCP was divided into two protocols: TCP and IP. Later, other protocols were added to the TCP/IP suite of protocols including Telnet, FTP, DNS, and many others.

Presentation_ID 23 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

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)

Presentation_ID 24 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Standards Organizations ISOC, IAB, and IETF

Presentation_ID 25 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Standards Organizations 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

Presentation_ID 26 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Standards Organizations Open Systems Interconnection (OSI)

OSI Model has 7 layers; data packets will travel through these layers.

The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

Presentation_ID 27 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Standards Organizations 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)

Presentation_ID 28 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Presentation_ID 29 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Models Compared

Presentation_ID 30 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Reference Models The TCP/IP Reference Model

Presentation_ID 31 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Reference Models Comparing the OSI and TCP/IP Models

© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential Presentation_ID 32

3.3 Moving Data in the Network

Presentation_ID 33 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

The Rules Message Sending process A message is broken into segments.

Each segment is encapsulated in a separate frame with the address information, and is sent over the network.

At the receiving host, the message is de-encapsulated and put back together to be processed and interpreted.

Presentation_ID 34 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation Communicating the Messages Segmenting message benefits

Different conversations can be interleaved (mixed together as one) Increased reliability of network communications

Segmenting message disadvantage Increased level of complexity – more programming processes are needed to split a message into segments

Presentation_ID 35 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation Protocol Data Units (PDUs)

Data (to be sent, such as an email)

Segment

Packet

Frame

Bits

Presentation_ID 36 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation OSI Protocol Data Units (PDUs)

During data encapsulation, headers are added to the previous data.

Presentation_ID 37 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation TCP/IP PDU

During protocol encapsulation, protocol headers of each OSI layer are added to the data.

Presentation_ID 38 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation TCP/IP Protocol De-encapsulation

Presentation_ID 39 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Moving Data in the Network Accessing Local Resources

Presentation_ID 40 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Accessing Local Resources MAC Address

A media access control address (MAC address) is the physical address of a computer. It is a unique identifier assigned to devices in a network segment. Using this address, data can reach the intended Destination.

Presentation_ID 41 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Accessing Local Resources Communicating with Device / Same Network

Presentation_ID 42 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Accessing Remote Resources Default Gateway

• In a TCP/IP network, nodes such as servers, workstations and network devices each have a defined default route setting

• This setting points to the default gateway where packets are sent to • The gateway is a router • Information for routing are stored in the PDU

Presentation_ID 43 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Accessing Remote Resources Communicating Device / Remote Network

One router controls traffic for one network. Data can be sent from one network to another network.

Presentation_ID 44 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

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.

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.

Presentation_ID 45 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Network Protocols and Communications Summary (cont.) In this chapter, you learned:

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.

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.

Presentation_ID 46 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

END OF CHAPTER 3

Presentation_ID 47 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

1. In a network, data are sent in the form of ________.

Before being sent, a message must be formatted and ___________.

Encapsulation means _______ together the data and functions that manipulate the data, and keeping them safe from outside interference and misuse.

Presentation_ID 48 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

1. In a network, data are sent in the form of messages.

Before being sent, a message must be formatted and encapsulated.

Encapsulation means binding together the data and functions that manipulate the data, and keeping them safe from outside interference and misuse.

Presentation_ID 49 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

2. A message has a minimum and maximum size.

It is broken into _________.

Each segment is encapsulated in a separate ________ with the address information. The size of one frame is usually limited.

The frames are sent to the receiving ____.

At the receiving host, each frame is __________ and put back together as a message. It is then processed and interpreted.

Presentation_ID 50 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 2. A message has a minimum and maximum size.

It is broken into segments.

Each segment is encapsulated in a separate frame with the address information. The size of one frame is usually limited.

The frames are sent to the receiving host.

At the receiving host, each frame is de-encapsulated and put back together as a message. It is then processed and interpreted.

Presentation_ID 51 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 3. The set of rules that governs how network traffic is controlled is called the _________ _________.

Access Method determines when it is ready for a computer to send a message to avoid a ___________ of information.

Presentation_ID 52 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 3. The set of rules that governs how network traffic is controlled is called the access method.

Access Method determines when it is ready for a computer to send a message to avoid a collision of information.

Presentation_ID 53 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 4. Source and destination hosts use ______ _______ to, - negotiate correct timing for successful communication - determine the amount of data to send, - determine the speed of sending.

Presentation_ID 54 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 4. Source and destination hosts use flow control to, - negotiate correct timing for successful communication - determine the amount of data to send, - determine the speed of sending.

Presentation_ID 55 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

5. When a message is sent, it can be received successfully.

But sometimes, the receiver may take too long to do so. A time duration for timeout needs to be set. This is known as _________ _________.

Presentation_ID 56 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

5. When a message is sent, it can be received successfully.

But sometimes, the receiver may take too long to do so. A time duration for timeout needs to be set. This is known as Response Timeout.

Presentation_ID 57 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 6. Three ways of sending messages are:

• ________

• ________

• ________

Presentation_ID 58 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 6. Three ways of sending messages are:

• Unicast (one-to-one) Unicast is communication between a single sender and a single receiver over a network.

• Multicast (one-to-many) Multicast is communication between a single sender and many interested receivers over a network.

• Broadcast (one-to-all) Broadcast is communication between a single sender and ALL devices in a network.

Presentation_ID 59 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

7. The four TCP/IPprotocol layers are:

A_________

T__________

I___________

N__________

Presentation_ID 60 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

7. The four protocol layers are:

Application Protocol – Hypertext Transfer Protocol (HTTP)

Transport Protocol – Transmission Control Protocol (TCP)

Internet Protocol – Internet Protocol (IP)

Network Access Protocols – Data link & physical layers

Presentation_ID 61 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

8. Four protocol suites used in the Industry are: • TCP/IP

• Novell Netware

Presentation_ID 62 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

8. Four protocol suites used in the Industry are: • TCP/IP • ISO • Apple Talk • Novell Netware

Presentation_ID 63 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

The OSI Model has _______ layers; ______ packets will travel through these layers.

9. The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the _____________ functions of a telecommunication or computing system.

Presentation_ID 64 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

The OSI Model has 7 layers; data packets will travel through these layers.

9. The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

Presentation_ID 65 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

10. Name the two models shown:

Presentation_ID 66 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

10. Name the two models shown:

Presentation_ID 67 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

11. PDU stands for _______ ______ _____. A PDU consists of,

Data

S_______

Packet

F______

Bits

Presentation_ID 68 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

11. PDU stands for Packet Data Unit. A PDU consists of,

Data

Segment

Packet

Frame

Bits

Presentation_ID 69 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Data Encapsulation OSI PDUs

12. During data encapsulation, headers are added to the previous data.

Segment = _______ header + data

Packet = _______ header + segment

Frame = _______ header + packet

Frame = set of ______

Presentation_ID 70 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

OSI PDUs 12. During data encapsulation, headers are added to the previous data.

Segment = transport header + data

Packet = network header + segment

Frame = frame header + packet

Frame = set of bits

Presentation_ID 71 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 13. During protocol encapsulation for TCP/IP model, protocol headers of each layer are added to the data. TCP segment = User Data + _____ header IP Packet = TCP segment + ____ header Ethernet Frame = IP packet + ______ header

Presentation_ID 72 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 13. During protocol encapsulation for TCP/IP model, protocol headers of each layer are added to the data. TCP segment = User Data + TCP header IP Packet = TCP segment + IP header Ethernet Frame = IP packet + Ethernet header

Presentation_ID 73 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 14. A media access control address (MAC address) is the _______ address of a computer. It is a unique identifier assigned to devices in a network segment. Using this address, data can reach the intended __________.

Presentation_ID 74 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 14. A media access control address (MAC address) is the physical address of a computer. It is a unique identifier assigned to devices in a network segment. Using this address, data can reach the intended Destination.

Presentation_ID 75 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 15. In a TCP/IP network, the ______ is a router. All data must pass this gateway to reach its network.

Presentation_ID 76 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review 15. In a TCP/IP network, the gateway is a router. All data must pass this gateway to reach its network.

Presentation_ID 77 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

16. One router controls ________ for one network. ______ can be sent from one network to another network.

Presentation_ID 78 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

Review

16. One router controls traffic for one network. Data can be sent from one network to another network.

Presentation_ID 79 © 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential

END OF REVIEW