2.2 - Network Devices

Question 1

Routers

Answer 1

• Routes traffic between IP subnets
  – Makes forwarding decisions based on IP address
  – Routers inside of switches sometimes called
  “layer 3 switches”
• Often connects diverse network types
  – LAN, WAN, copper, fiber

Question 2

Switches

Answer 2

• Bridging done in hardware
  – Application-specific integrated circuit (ASIC)
  – 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 routing functionality

Question 3

Unmanaged switches

Answer 3

• Very few configuration options
  – Plug and play
• Fixed configuration
  – No VLANs
• Very little integration with other devices
  – No management protocols
• Low price point
  – Simple is less expensive

Question 4

Managed switches

Answer 4

• VLAN support
  – Interconnect with other switches via 802.1Q
• Traffic prioritization
  – Voice traffic gets a higher priority
• Redundancy support
  – Spanning Tree Protocol (STP)
• Port mirroring
  – Capture packets
• External management
  – Simple Network Management Protocol (SNMP)

Question 5

Access point

Answer 5

• Not a wireless router
  – A wireless router is a router and an access point
  in a single device
• An access point is a bridge
  – Extends the wired network onto the wireless network
  – Makes forwarding decisions based on MAC address

Question 6

Patch Panels

Answer 6

• Combination of punch-down blocks and
  RJ-45 connectors
• Runs from desks are made once
  – Permanently punched down to patch panel
• Patch panel to switch can be easily changed
  – No special tools
  – Use existing cables

Question 7

Firewalls

Answer 7

• Filters traffic by port number
  – OSI layer 4 (TCP/UDP)
  – Some firewalls can filter based on the application
• 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 8

Power over Ethernet (PoE)

Answer 8

• Power provided on an Ethernet cable
  – One wire for both network and electricity
  – Phones, cameras, wireless access points
  – Useful in difficult-to-power areas
• Power provided at the switch
  – Built-in power - Endspans
  – In-line power injector - Midspans

Question 9

PoE switch

Answer 9

• Power over Ethernet
  – Commonly marked on the switch or interfaces

Question 10

PoE, PoE+, PoE++

Answer 10

• PoE: IEEE 802.3af-2003
  – The original PoE specification
  – Now part of the 802.3 standard
  – 15.4 watts DC power, 350 mA max current
• PoE+: IEEE 802.3at-2009
  – Now also part of the 802.3 standard
  – 25.5 watts DC power, 600 mA max current
• PoE++: IEEE 802.3bt-2018
  – 51 W (Type 3), 600 mA max current
  – 71.3 W (Type 4), 960 mA max current
  – PoE with 10GBASE-T

Question 11

Hub

Answer 11

• “Multi-port repeater”
  – Traffic going in one port is repeated to
  every other port
• Everything is half-duplex
• Becomes less efficient as network traffic increases
• 10 megabit / 100 megabit
• Difficult to find today

Question 12

Cable modem

Answer 12

• Broadband
  – Transmission across multiple frequencies
  – Different traffic types
• Data on the “cable” network
  – DOCSIS (Data Over Cable Service Interface Specification)
• High-speed networking
  – Speeds up to 1 Gigabit/s are available
• Multiple services
  – Data, voice, video

Question 13

DSL modem

Answer 13

• ADSL (Asymmetric Digital Subscriber Line)
  – Uses telephone lines
• Download speed is faster than the upload
  speed (asymmetric)
  – ~10,000 foot limitation from the central office (CO)
  – 52 Mbit/s downstream / 16 Mbit/s upstream are
  common
  – Faster speeds may be possible if closer to the CO

Question 14

ONT

Answer 14

• Optical network terminal
  – Fiber to the premises
• Connect the ISP fiber network to the copper network
  – Demarcation point (demarc) in the data center
  – Terminal box on the side of the building
• Line of responsibility
  – One side of the box is the ISP
  – Other side of the box is your network

Question 15

Network Interface Card (NIC)

Answer 15

• The fundamental network device
  – Every device on the network has a NIC
  – Computers, servers, printers, routers, switches,
  phones, tablets, cameras, etc.
• Specific to the network type
  – Ethernet, WAN, wireless, etc.
• Often built-in to the motherboard
  – Or added as an expansion card
• Many options - Single port, multi-port, copper, fiber