Networking Fundamentals

SMB University: Selling Cisco SMB Foundation Solutions

Objectives

• Describe the function and operation of a hub, a switch and a

router

• Describe the function and operation of a firewall and a

gateway

• Describe the function and operation of Layer 2 switching,

Layer 3 switching, and routing

• Identify the layers of the OSI model

• Describe the functionality of LAN, MAN, and WAN networks

• Identify the possible media types for LAN and WAN

connections

What is a Network?

• A network refers to two or more connected computers that

can share resources such as data, a printer, an Internet

connection, applications, or a combination of these

resources.

Types of Networks

Local Area Network (LAN)

Metropolitan Area Network (MAN)

Wide Area Network (WAN)

WAN Technologies

Circuit-switched

Asynchronous serial. ISDN Layer 1

TELEPHONE

COMPANY

Leased Line

Synchronous serial

WAN Technologies (Cont.)

Broadband Access

SERVICE

PROVIDER

Cable, DSL, Wireless WAN

Frame-Relay

Synchronous serial

SERVICE

PROVIDER

Network Topologies: Bus Topology

SEGMENT

Terminator

Network Topologies: Star Topology

Hub

Network Topologies:

Extended Star Topology

7

6

5

4

3

2

1

The OSI Model—

Why a Layered Network Model?

• Reduces complexity

• Standardizes interfaces

• Facilitates modular engineering

• Ensures interoperable technology

• Accelerates evolution

• Simplifies teaching and learning

Application

Presentation

Session

Transport

Network

Data Link

Physical

The Seven Layers of the OSI Model

Application Layers (Upper

Layers):

• Network Processes to

Applications

• Data Representation

• InterHost Communication

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

Network

Data Link

Physical

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

Network

Data Link

Physical

The Seven Layers of the OSI Model (Cont.)

End To End Connections:

• Handles transportation issues

between hosts

• Ensures data transport reliability

• Establishes, maintains and

terminates virtual circuits

• Provides reliability through fault

detection and recovery

• Information flow control

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

Network

Data Link

Physical

The Seven Layers of the OSI Model (Cont.)

Data Delivery:

• Provides connectivity and path

selection between two host

systems

• Routes data packets

• Selects best path to deliver data

• The Network layer prioritizes data

known as Quality of Service (QoS)

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

Network

Data Link

Physical

The Seven Layers of the OSI Model (Cont.)

Access to Media:

• Defines how data is formatted for

transmission and how access to

the network is controlled

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

Network

Data Link

Physical

The Seven Layers of the OSI Model (Cont.)

Binary Transmission:

• Defines the electrical, mechanical,

procedural, and functional

specifications for activating,

maintaining, and deactivating the

physical link

Twisted-Pair

Coaxial

Outer jacket

BNC

Connector

Copper Conductor

Braided Copper Shielding

Plastic Insulation

Fiber Optics

Outer jacket

Plastic Shield

Glass and Fiber Cladding

Kevlar Reinforcing Material

SC

Connector

Outer jacket

Twisted-Pair

Color-Coded Plastic Insulation

RJ-45

Connector

Physical Media Types

Wireless

Physical Media Types (Cont.)

INTERNET

ETHERNET BACKBONE

Physical Media Comparison

Twisted Pair

Coaxial Fiber Optic

Wireless

LAN

Bandwidth Up to 1 Gbps 10–100 Mbps

Up to

10 Gbps

or higher

Up to

54 Mbps

Distance Up to 100 m Up to 500 m Up to 60 km

Up to 100 m

Price

Least

expensive

Inexpensive

Most

expensive

Moderate

Hub or Repeater

• A hub (concentrator) is a device that repeats the signals it

receives on one port to all other ports. It is a central

connection point for several network devices.

Hub

Hub (Multiport Repeater)

Network Interface Card

WAN—Physical Layer Implementations

• Physical layer implementations vary

• Cable specifications define speed of link

Cisco

HDLC

PPP Frame

Relay

ISDN BRI (with

PPP)

DSL Modem Cable

Modem

EIA/TIA-232

EIA/TIA-449

X.21 V.24 V.35

HSSI

RJ-48

Note: ISDN BRI cable

pinouts are different than

the pinouts for Ethernet.

The RJ-48 and RJ-45

look the same, but the

pinouts are different.

RJ-11

Note: Works

over telephone

line

BNC

Note: Works

over Cable

TV line

WAN

Physical Media

Wall Jack

Data Link Layer

• Data Link layer protocols create, transmit, and receive

packets. This layer is also responsible for logical MAC

addressing and LLC processing, creating logical topologies,

and controlling media access.

2

Data Link

MAC Address

• The network interface card address, called the hardware

address, is protocol-independent and is usually assigned at

the factory. This address is technically called the media

access control address (MAC) because it is found on the

MAC sub layer of the Data Link layer.

2

Data Link

MAC Address Hardware Address

=

00-0C-F1-5E-BE-F2

Data Link Devices

• The Data Link layer is manipulated by two devices: bridges

and switches. These are more complex and more expensive

than their Physical layer counterparts, but they do have

advantages.

Switches

Bridges

Switch

• When a switch receives data the switch examines the data

link header for the MAC address of the destination station

and forwards it to the correct port. This opens a path

between ports that can use the full bandwidth of the

topology.

Network Layer

• The network layer provides connectivity and path selection

between two host systems that may be located on

geographically separated networks

3

Network

Network Layer (Cont.)

• IP is a standard that defines the manner in which the network

layers of two hosts interact. IP addresses are 32 bit long,

hierarchical addressing scheme.

3

Network

IP Address Logical Address

=

192.168.6.17

Network Layer Devices

• The devices that operate at the Network layer are routers and

Layer 3 Switches

Router

Layer 3 Switch

Routers

• Routers facilitate communication within this internet work. It

decides how to send packets within the network so that they

arrive at their destination.

Layer 3 Switches

• The Layer 3 switch functions at the Network layer and

performs the multiport, virtual LAN, data pipelining functions

of a standard Layer 2 switch. It can also perform basic

routing functions between virtual LANs.

Layer 3 Switch

Multilayer Switching

• Combines functionality of:

– Layer 2 switching

– Layer 3 switching

– Layer 4 switching

• High-speed scalability

• Low latency compared to routers

2

1

Physical

7

6

5

4

Application

Presentation

Session

3

Data Link

Transport

Network

Transport Layer Implementations

• The Transport layer is charge of the reliable/unreliable

transport of data. It can be implemented as TCP or UDP.

4

TCP

UDP

Transport

Gateway

• A gateway is a combination of hardware and software that

connects dissimilar network environments. It performs

translations at multiple layers of the open system

interconnection (OSI) model.

PC Network MAC Network

Gateway

OSI Model

Firewalls

• A firewall is a system or group of systems that manages

access between two or more networks

Outside

Network

Inside

Network

INTERNET

DMZ

Network

Summary

This lesson covered the following main topics:

• The function and operation of a hub, a switch, and a router

• The function and operation of Layer 2 switching, Layer 3

switching, and routing

• The OSI model

• Functionality of LAN, MAN and WAN networks

• Possible media types for LAN and WAN connections

• The function and definition of firewalls and gateways