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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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NICs, Repeaters, & Hubs
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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NICs, Repeaters, & Hubs
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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NICs, Repeaters, & Hubs
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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NICs, Repeaters, & Hubs
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.
21
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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
16
1
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
1
16
1
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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Routers Two Main Functions
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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Routers Two Main Functions
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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Devices Function At Layers
Also know that eachdevice not only works at
its layer, but all layersbelow it.
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Devices Function At Layers
For example, a router isa layer 3 device but also
uses MAC addresses(layer 2) and repeatsthe signal (layer 1)
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Devices Function At Layers
At what layers dothese two operate?
The Cloud
ALL 7 LAYERS!!One last bit of information