© 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Version 4.0 Communicating over the Network Network Fundamentals – Chapter 2 Sandra Coleman,

© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 1Version 4.0

Communicating over the Network

Network Fundamentals – Chapter 2

Sandra Coleman, CCNA, CCAI

2© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Objectives Describe the structure of a network, including the

devices and media that are necessary for successful communications.

Explain the function of protocols in network communications.

Explain the advantages of using a layered model to describe network functionality.

Describe the role of each layer in two recognized network models: The TCP/IP model and the OSI model.

Describe the importance of addressing and naming schemes in network communications.

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Network Structure Three elements of communication

• Message source

• The channel

• Message destination

– Data or information networks capable of carrying many different types of communications

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How are messages communicated?– Data is sent across a network in small “chunks” called segments – known as

segmentation

– Multiplexing – describes the process of interleaving multiple digital data streams into ONE signal (see example in online curriculum 2.1.2)

– It increases the reliability of network communications

– Disadvantage is the amount of encapsulation that must occur with every segment, especially for large amounts of data!

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Network Components• Hardware (includes devices and media)

• Software (services and processes)

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End Devices– End devices form interface with human network &

communications network

– Originate data flow!

– Examples: computers, printers, VoIP Phones, cameras, cell phones, etc.

– Commonly referred to as hosts (source or destination of a message)

– Each host has an address that will identify it on the network

– Role of end devices:• Client (software installed so they can request & display info from the

server)

• Server (provide information and services to other hosts)

• Both client and server

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Intermediary Devices

–Role of an intermediary device• Examples: Hubs, switches, access points, routers,

modems, firewalls, etc.

• Provides connectivity and manages data flows across network

• Works behind the scenes

• Determines the path data will travel to get from source to destination

• Knows all the paths that exist

• Informs other like devices about errors or communication failures

• Retimes & retransmits signals as necessary

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Network Media– this is the channel over which a message travels

– Encoding is different for each type, i.e. electrical impulses, light pulses, wave patterns

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Local Area Networks (LANs)– A network serving a home, building or campus is considered a

Local Area Network (LAN)

– Single geographic area, usually a common organization

– Administered by a single organization

– Provides network services to a common organization

Network Types

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Network Types Wide Area Networks (WANs)

– LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN)

– Be able to identify a LAN and a WAN given a similar diagram

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Network Types Define the Internet

– The internet is defined as a global mesh of interconnected networks

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Network Symbols – be able to recognize

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Function of Protocol in Network Communication– A protocol is a set of predetermined rules

– Implemented in software that is loaded on each host and network device

– View them as a stack – from low to high in a hierarchy

– Outline the functions necessary to communicate between layers

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– Network protocols are used to allow devices to communicate successfully

– Protocols agree on structure of message (specific to PDU’s)

– Protocols agree on the process of sharing, error handling, and termination procedures – all functions necessary for communication

– Require layer dependent encapsulations

Network Protocols

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Protocols and Industry standards– A standard is a process or protocol that has been endorsed by

the networking industry and ratified by a standards organization

– Ensures all protocols (open or proprietary) will work together

– IEEE (Institute of Electrical and Electronic Engineers)

– IETF (Internet Engineering Task Force)

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Function of Protocol in Network Communication

Examples of Protocols

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Function of Protocol in Network Communication Technology independent Protocols

– Many diverse types of devices can communicate using the same sets of protocols

– This is because protocols specify network functionality, not the underlying technology to support this functionality

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Layers with TCP/IP and OSI Model Benefits of using a layered model

• Assists in protocol design

• Fosters competition (different vendors can work together)

• Changes in one layer do not affect other layers

• Provides a common language

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Layers with TCP/IP and OSI Model

Away

Pizza

Sausage

Throw

Not

Do

Programmers

Know the layers in order!

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Layers with TCP/IP and OSI Model TCP/IP Model – created in early 1970s – KNOW what

each layer is responsible for!

Open Standard

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Layers with TCP/IP and OSI Model

Protocol data units (PDU) and encapsulation

PDUs are SPECIFIC to each

layer!

Know PDUs at EACH layer!

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Key functions of encapsulation

Ensure that data pieces get from sending to receiving device

Ability to re-assemble the data packets correctly

Ability to identify data packets that belong together with the same communication package

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Comparing TCP/IP and OSI ModelKnow these layers and how they compare between the

two models

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Addressing and Naming Schemes Explain how labels in encapsulation headers are used

to manage communication in data networks

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Addressing and Naming Schemes Describe examples of Ethernet MAC Addresses, IP

Addresses, and TCP/UDP Port numbers

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Addressing and Naming Schemes Think about a computer that has only one network

interface on it. All the data streams created by the applications that are running on the PC enter and leave through that one interface, yet instant messages do not popup in the middle of word processor document or e-mail showing up in a game.

This is because the individual processes running on the source and destination hosts communicate with each other. Each application or service is represented at Layer 4 by a port number.

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Things to do NOW!

Demonstrate tracert

Demonstrate packet tracer…how to set up a network

Map them a drive to Public…

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Ch. 2 is Finished! Homework – due on test day!

Study Guide

p. 34 – Matching (table 2-1 & 2-2)

p. 35-36 – Matching (table 2-3 & 2-4)

p. 37-38 – Matching (table 2-5 & 2-6)

Packet Tracer Activities in the textbook

2.2.4.2 (pg. 44)

2.4.8.2 (pg. 54)

Labs & Skills Integration

•Lab 2-1 (Do this on PT 2.6.1.2, pg. 48 in lab book- I have the files from the CD loaded on public)

•Ch. 2 Test will be on Tuesday Sept. 5 or Wed. Sept 6, 2012

•Online Test – Must be taken by midnight on Sunday September 2, 2012. I will NOT turn it on again!