Networking Devices

Question 1

Hub

Answer 1

• “Multi-port repeater”
• Traffic going in one port is repeated to every other
port
• OSI Layer 1

• Everything is half-duplex
• Becomes less efficient as network speeds increase
• 10 megabit / 100 megabit
• Difficult to find today

Question 2

Bridge

Answer 2

• Imagine a switch with two to four ports
  
  • Makes forwarding decisions in software

• Connects different physical networks
• Can connect different topologies
• Gets around physical network size limitations /
collisions

• OSI Layer 2 device
  
  • Distributes traffic based on MAC address
• Most bridges these days are wireless access points
  
  • Bridges wired Ethernet to wireless

Question 3

Switch

Answer 3

• Bridging done in hardware
  
  • Application-specific integrated circuit (ASIC)
• An OSI layer 2 device
  
  • Forwards traffic based on data link address
• Many ports and features
  
  • The core of an enterprise network
  • May provide Power over Ethernet (PoE)
• Multilayer switch
  
  • Includes Layer 3 (routing) functionality

Question 4

Router

Answer 4

• Routes traffic between IP subnets
  • OSI layer 3 device
  • Routers inside of switches sometimes called “layer 3 
     switches”
  • Layer 2 = Switch
  • Layer 3 = Router

• Often connects diverse network types
  
  • LAN, WAN, copper, fiber

Question 5

Firewall

Answer 5

• Filters traffic by port number
  
  • OSI layer 4 (TCP/UDP)
  • Some firewalls can filter through OSI layer 7
• Can encrypt traffic into/out of the network
  
  • Protect your traffic between sites
• Can proxy traffic
  
  • A common security technique
• Most firewalls can be layer 3 devices (routers)
  
  • Usually sits on the ingress/egress of the network

Question 6

Wireless access point (WAP)

Answer 6

• Not a wireless router
• A wireless router is a router and a WAP in a single
device

• WAP is a bridge
• Extends the wired network onto the wireless
network
• WAP is an OSI layer 2 device

Question 7

Converting media

Answer 7

• OSI Layer 1
  
  • Physical layer signal conversion
• Extend a copper wire over a long distance
  
  • Convert it to fiber, and back again
• You have fiber
  
  • The switch only has copper ports
• Almost always powered
  
  • Especially fiber to copper

Question 8

Wireless range extender

Answer 8

• Wireless never seems to stretch far enough
• We can’t always choose where to install an access
point

• Extend the reach of a wireless network
  
  • A wireless repeater

Question 9

VoIP endpoint

Answer 9

• Some people still communicate using voice
  
  • We now send this using VoIP

• The device can now be anything
• Traditional phone handset, desktop application,
mobile device app