NETWORKING
COMPONENTS
AN OVERVIEW OF COMMONLY
USED HARDWARE
Christopher Johnson
LTEC 4550
Hub

Ethernet Hub (shown)
 Link
multiple hosts to single central point
 Can be used to share single network connection, for
example, or multiple USB devices sharing a single
USB port over a USB hub



Broadcasts network traffic to all connected hosts
Operates at OSI Layer 1
Serves as signal
repeater, boosting
strength of broadcast
messages
How it works - Hub
Desktop with Ethernet
NIC.
Desktop with
Ethernet NIC.
Ethernet hub
8-port ethernet hub. Supports source
device plus up to 7 additional devices
Laptop with Ethernet
interface.
Single
Ethernet
port.
This could be a
network port in
a cubicle on an
Ethernet-wired
corporate
network, for
example
Switch

Ethernet switch (shown)
 Connects
multiple devices to central point
 Can be used to build small
peer-to-peer network

Communicates on OSI
Layer 2
 Usually
contains software to build routing table
 Directs traffic on network to proper hosts – doesn’t
broadcast traffic to all devices like a hub
How it works - Switch
Desktop with Ethernet
NIC.
Desktop with
Ethernet NIC.
Desktop with
Ethernet NIC.
Desktop with
Ethernet NIC.
Ethernet switch
8-port Ethernet switch. Connect up to 8
devices on a peer-to-peer network
Laptop with Ethernet
interface.
Router

Router (wireless router shown)
 Acts
as a connector between
two different networks
 Directs traffic from nodes on
one network to the correct
node on the second network

Communicates on OSI
Layer 3
 Directs
traffic on network to proper hosts – uses IP
addresses to route packets
How it works - Router
Desktop with Ethernet
NIC.
From Internet
(through ISP)
Desktop with
Ethernet NIC.
Desktop with
Ethernet NIC.
XBOX 360 with WiFi
network adapter.
Wireless Router
5-port Ethernet router plus Wireless
router. Connect up to 5 wired devices
plus up more than 200 wireless devices
Laptop with WiFi
network adapter
Bridge

Networking Bridge
Acts as a connector between two different network
segments
 Builds forwarding database
containing list of nodes on
each segment


Communicates on OSI Layer 2
Uses hardware-based MAC addresses to direct traffic
 Filters network traffic (frames)

Forwards to different network segment when destination
address is not on local segment
 Drops frames if destination address is on same segment as
source

How it works - Bridge
Node A
Node B
Node C
Network Segment 1
Node D
Ethernet Bridge
Connects Network Segment 1 to Network
Segment 2. Let’s assume, on a newly
implemented network, Node A sends a packet to
Node E. First, the frame containing the packet
would travel to the bridge. A record for Node A
address would be added to the bridge’s
address table. Then, the frame would be
broadcast to Nodes D, E and F. Node D and F
would ignore the frame, while E would respond
back to the bridge. The address for Node E is
recorded, and then Nodes A and E may
communicate through the bridge, across their
different network segments.
Node E
Node F
Network Segment 2
Gateway

Gateway – node at the edge of a network
Serves as a point of entry from one
network to another
 Capble of joining two networks built
on different protocols
 Commonly combined with firewalls
due to their position at the edge of
a given network


Can communicate on any OSI layer
Can be implemented either by hardware or software
 Routers are a special type of gateway
 PCs can be configured to be a gateway

How it works - Gateway
Wireless Router
From Internet
(through ISP)
Node A
Gateway
Node B
-- OR --
Node C
Home Network
Desktop with
two Ethernet
NICs.
One NIC is
connected to
internal network,
and other is
connected to
external network.
Serves as a point of entry from one
network to another. In this case, the
home network is connected to the
Internet through either a wireless
router or another PC which is
configured as a router.
A gateway can thus be implemented
either by hardware (with the router)
or software (with the specially
configured PC)
Firewall

Firewall (hardware firewall shown)
Device which permits or denies network connections based
on rules (i.e. restricted ports
or source addresses
 Can be either hardware or
software based
 Provides security to nodes behind it
 Many routers contain basic firewall functionality


Hardware Firewalls


Work on first 4 layers of OSI model
Software Firewalls
Most operating systems contain basic firewall functionality
 Operates at Application Layer of OSI model

How it works - Firewall
From Internet
(through ISP)
Node A
Hardware Firewall
Node B
Node C
Home Network
Firewall
Filters network traffic coming in to the
network from external source.
Hardware firewalls operate on the
first 4 layers OSI layers, blocking
content based on MAC addresses or
IP addresses, or based on type of
content and destination port on
protected computers.
Can also be implemented on
application layer of OSI by softwarebased firewall. Software firewalls
block traffic based on IP address or
MAC address or content.
Wireless Access Point

Wireless Access Point (wireless router shown)
Device which broadcasts traffic from one network to
another or between connected nodes on
the same network
 Utilizes wireless signal to configure the
network connections, making networks
easy to set up and maintain
 Provides routing functionality
 May also contain firewall functionality to
control flow of traffic and content throughout
and between local networks and WANs.


Works on Layer 3 of OSI model
How it works – Wireless Access Point
Belkin Router
Wireless G+ MIMO
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Easy setup through web interface
Configure router to handle DHCP
connections
Set WPA encryption
Can configure to restrict access to
specific MAC addresses
Built-in firewall
Port forwarding and other virtual
server functions
Can manually configure DNS
settings
From Internet
(through ISP)
Wireless Access Point
Connects multiple devices to a single
connection to another network.
Commonly used in homes to set up
wireless networks servicing multiple
consumer devices.
Laptop PCs with
WiFi NICs.
Also used in public places providing
temporary internet access to a
variable number of customers.
Range of Prices for Hardware
Device
Price Range
Hub (gigabit Ethernet, 8 port)
$80 - $160
Switch (gigabit Ethernet, 24 port)
$440 - $500
Router
$200 - $800
Bridge
$80 - $200
Gateway
$150 - 300
Firewall
$129 - $300
Wireless AP
$100 - $800
These prices represent products with mid-range capabilities. Since there is such a vast
number of products on the market, with a wide range of capabilities, the products
priced here would be suitable for medium size offices or small school environments.
Networking components – a sample setup using all
components we’ve discussed
Gateway
Network Attached
Storage (NAS) Devices
Motorola cable modem
serves as a gateway
between home sample
network and the Internet
Contains shared documents
and media content.
Hub
Router/Wireless
AP/Firewall
NAS drives
share
connection to
switch
Firewall
Switch
Workstation B Workstation A
From Internet
(through ISP)
Hardware firewall
will be used to
secure traffic to
wired network
Bridge
Connecting wireless and
wired networks
Contains softwarebased firewall. We
will configure this to
protect the wireless
network
Server
Configured to
manage resources on
wired network
Network connected to Internet through gateway. Wireless network connects to
Wireless AP/Router. Wired network connects to switch, then to firewall, then to
gateway. NAS devices connect to hub and then to switch for access on wired
network. Bridge connects wired and wireless networks.