Demo Networking Devices

7/29/2019 Demo Networking Devices

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Networking Devices


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Evolution of LAN Devices

NICs, Repeaters, & Hubs

BridgesSwitches

Routers


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NIC Specifics

NICs provide hosts with access tomedia by using a MAC address.

MAC stands for Media Access Control

NICs operate at Layer 2 !!


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To connect two computers, you must...

Install a NIC card in each.

The First LAN

NIC

NIC

NIC NIC

Attach computers using a crossover cable


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Repeaters can be usedto increase the distance

Whats the maximum distancefor Cat 5 cable?00 meters or approx. 300 feet

So what can we use if this distance

is greater than 100 meters?

NIC NIC

Repeaters amplify and

retime signals


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NIC NIC

NIC NIC

Using repeaters was fine as long as a businessonly needed two computers networked.

What if a business wanted athird computer attached?

Or a fourth? What

device would they need?


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NIC NIC

NIC NIC

A multi-port repeater!Also called a...Hub


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A Dilemma!

NIC NIC

NIC NIC

As businesses expanded theirnetworks, they began tocascade hubs.


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Whats The Problem?

1) Hubs share bandwidth between allattached devices.

2) Hubs are stupid, Layer 1 devices.They cannot filter traffic.

3) Most LANs use a broadcast topology,

so every device sees every packetsent down the media.

Lets take a look at how broadcasting works


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BroadcastsIn this picture, all hubs forwardall traffic to all devices.


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So, if Host 1 wants ping Host 2, allhosts see the ping. This is what we

mean by a broadcast topology

Broadcasts

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The red arrows show that all hosts receive theping request. Only Host 2 will respond.


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Whats The Solution?

We need a smarter hub!

Whats a smarter hub called?

A Bridge!

Bridges filter network traffic based on

MAC addresses.

Lets take a look at how this works.


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BridgeTo lessen the amount of LAN traffic,businesses began to use bridges tofilter frames based on MAC addresses.


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BridgeNow, if Host 1 pings Host 2, only thehosts on that LAN segment see theping. The bridges stop the ping.

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SwitchA switch (also know as a multi-portbridge), can effectively replace thesefour bridges.


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SwitchAnother benefit of a switch is that eachLAN segment gets dedicated bandwidth.

The Cloud

10 Mbps0 Mbps

10 Mbps10 Mbps

10 Mbps


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Since a switch is a multi-port bridge,we know it will stop local pings fromtraveling to other network segments.

Switch

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But a switch cannot stop a ping destinedfor a different LAN segment fromtraveling to all other LAN segments.


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Switch

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For example, Host 1 pings Host 16. Since Host16 is on another LAN segment, the switch will

flood the ping request out all ports.

What device will solve this problem?


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Router

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Routers filter traffic based on IP addresses.The IP address tells the router which LAN

segment the ping belongs to.


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Routers Two Main Functions

Path Determination

Packet Switching


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Path Determination is the process of

evaluating a packets destination IP

address so that the router can decide

which port to send out the packet.


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In Packet Switching, the router re-

encapsulates the packet in the protocol

needed for the specified port and then

switches the packet out that port.


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Devices Function At Layers

Know These!


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Also know that eachdevice not only works at

its layer, but all layersbelow it.


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For example, a router isa layer 3 device but also

uses MAC addresses(layer 2) and repeatsthe signal (layer 1)


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At what layers dothese two operate?

The Cloud

ALL 7 LAYERS!!One last bit of information

Demo Networking Devices

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