Connecting to the Network

Networking for Home and Small Businesses – Chapter 3

What is a network?

The ability to connect people and equipment no matter where they are in the world.

– telephone

– computers

– television

How does your body work as a network??

Networking and Its BenefitsA CONVERGED NETWORK!!!

Networks = Sharing Resources Main reason for networking – sharing resources

– File sharing – Why disable- allows more security

– Print sharing

Consider this before sharing:– security issues

– permissions granted

Windows XP users– use Simple File Sharing

Networking and Its Benefits

SOHO Network– Small Office/Home Office

Networking and Its Benefits Define the components of an Information network

Hosts– PCs

– send and receive information across the network

–connected to a network device

Peripherals– not directly connected to the network, but connected to hosts

Network devices– hub, switch, router

Network media– used to connect hosts/devices

Networking and Its Benefits Clients and servers

– software installed determines the role of a client or a server

Server software– enables the server to provide information to other hosts

Client software– enables the client to request and display information from the server

– Example: Internet Explorer

Networking and Its Benefits Build computer peer-to-peer network and verify

The ability to act as both a client and server

Networking and Its Benefits

Schools, Corporations

Internet

Network Topologies Physical topology (Blueprint of a network)

– created to record where each host is on the network

– shows how each host is connected (media, devices, etc)

Network Topologies Logical topology (Behind The Scenes Information)

– how the host uses the network

– host names, addresses, groups, applications

Physical and Logical Network Development

Using the handout (online within Mr. Smith’s webpage)as a guide and your creativity, design the physical and logical topology for ABC Banking Center.

Please read the entire handout before beginning as important information is contained throughout and will need to be understood before making your first decision on the overall design.

Project is worth a 250 points.

Business Equipment Purchase Task

Using the handout with the specifications for the ABC Banking Center research components that will be used to help form a complete computer network.

When finished please submit for a 200 point grade.

Two sites will be utilized 1) www.cdw.com and 2) www.newegg.com

Communication Protocols Primary purpose of a network – to communicate & share

Elements of communication– Sender (source)

• has a need to communicate

– Receiver (destination)

• receives message and interprets it

– Channel

• pathway for information to travel

Successful delivery of the message

Rules (protocols) must be followed:– Identification of the sender and/or receiver

– Channel in which to communicate (face-to-face)

– Mode of communication (written or spoken)

– Language

– Grammar

– Speed or timing

Communication Protocols Encoding vs. Decoding

Encoding – Humans

• converting thoughts into language, symbols, or sounds

– Computers

• messages converted into bits

• each bit encoded into sound, light, or electrical impulses

• destination host then decodes

Decoding– reverse of encoding

In Class Task

Can you encode and decode. Try to decode the messages provided and then encode a message of your own.

Communication Protocols Messages have size restrictions depending on the

channel used

If the message is broken into smaller pieces, it is easier to understand

If the message is too long or too short, will be considered undeliverable.

Communication Protocols Message Patterns

Unicast – single destination

Multicast – same message to a group

Broadcast – all hosts need to receive the message

Encapsulation– placing the letter into the envelope(one message format into another message format so that it can be delivered)

Go to page 3.2.7.1 to see the various message patterns

Communication Protocols

PROTOCOLS = RULES TO FOLLOW

Communication Across a Local Ethernet Network Computers must speak the same language in order to

communicate!!

Standards in technology

Standards – rules by which equipment from different vendors operate

Benefits of standards:–Simplify new product development

– Promote competition

– Provides consistent interconnections across networks

Communication Across a Local Ethernet Network IEEE (Institute of Electrical and Electronic Engineers)

– maintains networking standards

– 802.3 – Ethernet standard

A breakdown of terminology– 100 Base-T

– 100 = Speed in Mbps-**SPEED

– Base = Baseband transmission**Transmission Type

– T = Twisted Pair**Type Of Media

Communication Across a Local Ethernet Network Ethernet communication

– each device has a MAC address

– each device may look at the data, but only the device that matches the destination MAC will respond

–NIC will look at the destination MAC address and decide if it will accept a frame.

The Ethernet Frame (3.3.4.1 for image) Preamble – beginning of the timing

SFD (Start Frame Delimiter) – marks the end of the timing, but beginning of the frame

Destination MAC

Source MAC **Only MAC Addresses are used in Ethernet Frames**

Length/Type– Length – tells which protocol receives the data

– Type – number of bytes of data

Encapsulation –information to be sent

FCS (Frame Check Sequence) – checks for damaged frames/errors

Activity

Go to page 3.3.4.2 and complete the activity using the Ethernet frame

Logical Addressing MAC vs. IP

IP Address (Logical Address)

– assigned based on where the host is located

– assigned by the administrator

Logical Addresses (IP Addresses) are used to help determine the network a host is located on

Parts of an IP address

– Network – same for all hosts connected to the LAN

– Host – unique to each host on the network

MAC Address (Physical Address)

–Assigned by the designer of the NIC within a computer

–Used to identify the exact machine that is needed within a network.

MAC Address Lab

Complete the lab on page 3.3.3.2 and write down all answers to the questions that are posed on a sheet of paper. Please skip over step Step 4 Question C as this will cause your screen and computer to be blocked by IMPERO.

The Hierarchical Design Structure Divided into three layers

– Access Layer

• connection to the hosts

– Distribution Layer

• interconnects smaller networks

– Core Layer

• high speed connection between

distribution devices

Access Layer Devices Most basic level

Made up of:– host devices

– first line of networking devices

– hub, switch, workstations-the entry level devices

Access Layer Device – A HUB

Accepts data signal from one port and sends it out all ports

Collisions– results in message being garbled and unreadable

– occur when two or more hosts send a message at the same time (undesirable in a network)

NOT VERY SMART– a hub does not make decisions

Hubs And Collision Domains Collision domain – area where information runs into

others pieces of information. Collision domains can be broken up by the following devices 1)Router,2)Switch 3) Bridge

More collision domains = better performance

How many collision domains exist in the graphic shown?

Hub Activity

3.4.2.3 within the Cisco curriculum

Access Layer Device – A SWITCH

SMARTER THAN A HUB (Look at 3.4.3.1) dedicated bandwidth out each port

sends info to the intended recipients only!!

Can forward messages to a specific host by looking in its MAC table

If destination MAC is not in its MAC table,a switch sends out a request.

Only the host with the correct MAC address will respond

Collision Domain

Collision Domains– each port on a switch is its own collision domain

– 8 port switch = 8 collision domains

Switch Activity

3.4.3.4 from the Cisco curriculum

Broadcasts If there is only one destination MAC in a message, how

can you contact everyone else?– send a broadcast MAC

– hexidecimal digits FFFF.FFFF.FFFF represent a broadcast

Useful when hosts need to send information but don’t know what hosts are to receive it

Switches and hubs send the broadcast out to everyone on their network. (Broadcast Domain)

ARP Request

Sent when the sending host knows the destination IP, but not the MAC

Will discover the MAC address of any local host on the network

Distribution Layer Devices—The Router

Routers – directs traffic based on the destination IP address

Routers build routing tables; to help make decisions about which port to send information.

Look only the network portion of the IP address– finds the best path to take to get to the destination

Routers do not forward broadcasts, it keeps them contained!!!

Distribution Layer Devices—The Router

What does a router do after it determines that a data packet from Network 1 should be forwarded to Network 2?

- It reassembles the frame with different MAC addresses than the original frame.

Default Gateway Used when a host wants to send data to a host on a different

network. An incorrect default gateway can stop all traffic from leaving the original network. Local computers and hosts can communicate but will not be able to communicate with anyone outside of the network.

The device commonly used as the default gateway is the router interface closest to the computer

Complete the activity on page 3.5.3.2 using default gateways

Types of Routing

Dynamic

– information is obtained from neighboring routers

Static

– manually entered by the network administrator

What happen to a message that is not in the routing table?

– It is dropped unless . . .

A default route is set

– “last resort” type of router

– will send it to the router it thinks may be have the destination IP

–Used of no route is found in the routing table

The Layers

Go to page 3.3.7.2 and use your new knowledge over the three layers to answer 4 scenario questions.

Multifunction Devices Integrated routers

– Linksys wireless router

– problem = single point of failure

Cisco Integrated Services Router (ISR)– performs services of three different devices

• router

• switch

• wireless access point