Ing Ccna

Sybex CCNA 640-802
Chapter 1: Internetworking
Instructor & Todd Lammle

Chapter 1 Objectives
• The CCNA Topics Covered in this chapter include: – Internetworking Basics – Layered Models – The OSI Model – Ethernet Networking – Data Encapsulation – Cisco’s Three-Layer Model – Chapter 1 Written Labs and Review Questions
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Internetworking Basics
How would you say the PC named Bobcommunicates with the PC named Sally?

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Internetworking Basics
Switches can replace the hub, breaking up collision domains.

Keep in mind that the hub used in the figure just extended the one collision domain from the switch port.
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Internetworking Basics
Here’s a list of some of the things that commonly cause LAN traffic congestion:

•Too many hosts in a broadcast domain
•Broadcaststorms •Multicasting •Low bandwidth •Adding hubs for connectivity to the network

•A bunch of ARP or IPX traffic (IPX is a Novell protocol that is like IP, but really, really chatty. Typically not used in today’s networks.)

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Internetworking Basics

Routers create an internetwork.
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Internetworking Basics
There are two advantages of using routers in your network:

•They don’tforward broadcasts by default.
•They can filter the network based on layer 3 (Network layer) information (e.g., IP address).

Four router functions in your network can be listed as follows:
•Packet switching

•Packet filtering •Internetwork communication
•Path selection
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Internetworking Basics
Internetworking devices

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Internetworking Basics
Switched networks creating aninternetwork

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Layered Models
The Layered Approach
• • A reference model is a conceptual blueprint of how communications should take place. It addresses all the processes required for effective communication and divides these processes into logical groupings called layers. When a communication system is designed in this manner, it’s known as layered architecture.

•

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The OSI Model• The OSI isn’t a physical model. Rather, it’s a set of guidelines that application developers can use to create and implement applications that run on a network. • It also provides a framework for creating and implementing networking standards, devices, and internetworking schemes.

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The OSI Model
The upper layers

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The OSI Model
The lower layers

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The OSI Model
TheLayer Functions

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The OSI Model
Connection-Oriented Communication

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The OSI Model
Windowing

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The OSI Model
Network Layer Routing Table used in a router

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The OSI Model
Router in an internetwork

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The OSI Model
Data Link Layer

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Binary Addressing
Binary to Decimal Memorization Chart 10000000 128 11000000 192 11100000 224 11110000 240 11111000248 11111100 252 11111110 254 11111111 255

Conversion Example
BINARY
10000100 11010010 10111000 10100110

128
1 1 1 1

64
0 1 0 0

32
0 0 1 1

16
0 1 1 0

8
0 0 1 0

4
1 0 0 1

2
0 1 0 1

1
0 0 0 0

DECIMAL
132 210 184 166

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The OSI Model
A hub in an network

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The OSI Model
A Switch in an network

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Ethernet Networking
• Ethernet is acontention media access method that allows all hosts on a network to share the same bandwidth of a link. Ethernet is popular because it’s readily scalable, meaning that it’s comparatively easy to integrate new technologies, such as Fast Ethernet and Gigabit Ethernet, into an existing network infrastructure. It’s also relatively simple to implement in the first place, and with it, troubleshooting isreasonably straightforward.

•

•

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Ethernet Collision Detection
CSMA/CD

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Half and Full Duplex
Half-duplex Ethernet is defined in the original 802.3 Ethernet; Cisco says it uses only one wire pair with a digital signal running in both directions on the wire. But full-duplex Ethernet uses two pairs of wires instead of one wire pair like half duplex. And full duplex uses a...