T. Meredith
5460 – Summer 2014
Basic Components of a Computer Network
• Hub/Switch
• Router
• Bridge
• Gateway
Not all components
are used in every
network environment
– however, this
presentation discusses
all of them since any
or all may be present
in networks you will
support…
• Firewall
• Wireless Access Point (WAP)
Hub
• Transmits data from one
port/device to all other
devices connected to the hub
• Operates on Layer 1 of OSI
model
• Rarely used today, replaced
by switches
http://upload.wikimedia.org/wikipedia/commons/thumb/d/d9/4_port_netgear_ethernet_hub.jpg/300px-4_port_netgear_ethernet_hub.jpg
• Price: NA/obsolete
Today, hubs are usually superseded by…
Switch
http://img.directindustry.com/images_di/photo-g/rack-mount-managed-ethernet-switches-66478-5577201.jpg
• Transmits data from one
port/device to another
port/device connected to the
switch, correctly identified by
MAC addresses, ATM, or MPLS;
only sends data to correct
port/device, unlike hub
• Operates on Layer 2 of OSI model
• Price: $25 - $3000 (as pictured,
$825)
Diagram of hub/switch
placement in a network
Hub vs. Switch - clarifying differences…
http://content.answcdn.com/main/content/img/CDE/HUBSWIT.GIF
https://www.youtube.com/watch?v=JtTkW6pFxls
Bridge
• Does many of the same
things as a switch, BUT does
not use ATM or MPLS (MAC
addressing only)
• Typically connects two
different parts of the same
LAN
http://www.foundvalue.com/upload/images/products/alindo_632837444737955000_linksys_wet11.jpg
• Price: $30 - $17,000 and up
(as pictured, $100)
A bridge connecting two
smaller groups of clients
on a single LAN
http://www.igcseict.info/theory/4/hware/files/stacks_image_7406_1.png
Router
• Transmits data packets
between networks by using
routing table to determine
proper destination
• May include switch, firewall,
or other network functions
all in one device
http://www.wikimedia.org/wikipedia/commons/3/34/Linksys-Wireless-G-Router.jpg
• Price: $30 - $600 (as
pictured, $62)
A simple network
showing a router
connecting a LAN to the
Internet
http://www.igcseict.info/theory/4/hware/files/stacks_image_7380_1.png
Gateway
http://www.logicsupply.com/daq-ml250/#
• Similar functions as a router,
but more complex since it can
be used to connect two
different networks (e.g., LAN
and WAN/Internet) using
different protocols (e.g.,
VoIP)
• Can operate at any OSI layer
• Cost: $40 - $17,000 and up (as
pictured, $630)
An example of a
residential gateway on a
simple home network
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Homenet.svg/310px-Homenet.svg.png
Firewall
• Protects a network by
blocking
unrecognized/unauthorized
traffic from outside the LAN
• Can be a physical device OR
software running on a router
or other computer
http://eandt.theiet.org/magazine/2013/08/images/640_cisco-asa-firewall.jpg
• Price: $5/year minimum
(software license), up to
$2,000 Cisco rack-mountable
devices (as pictured, $640)
The position of a firewall
between a LAN and the
Internet
http://www.igcseict.info/theory/4/hware/files/stacks_image_7419_1.png
Wireless Access Point (WAP)
• Broadcasts a WiFi signal to
allow wireless devices to
connect to a wired network
http://img.directindustry.com/images_di/photo-g/wireless-access-points-waps-61398-3133227.jpg
• Usually connected (wired) to
a router, but some WAPs and
routers are single integrated
units
• Price: $25 - $3,000 (as
pictured, $1100)
A wireless access point
added to a network
http://www.pcguidebook.com/images/usingaprintserver.gif
Network Diagram
Often
integrated
(or Gateway)
References
• Black, U. D., & Habraken, J. W. (2009). Sam’s teach yourself networking in
24 hours. Indianapolis, Ind: Sams.
• All prices from: http://www.cdwg.com (accessed July 7, 2014)
• All images/media credited in individual slides