P.M. CompTIA A+ Core 1 Ch. 2.2 Network Devices / Software Defined Networking

Network devices

• Many different devices and components
- All have different roles

• Some of these functions are combined together
- Wireless router/switch/firewall

• Compare different devices
- Understand when they should be use

Routes

• 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

Switches

• 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

Unmanaged switches

• 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

Managed switches

• 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)

Access point

• 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

Patch Panels

• 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

Firewalls

Firewalls
• 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

Power over Ethernet (PoE)

• 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

PoE switch

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

PoE, PoE+, PoE++

• 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

Hub

• "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

Cable modem

• 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

DSL Modem

• 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

ONT

• 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

Network Interface Card (NIC)

• 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

SDN (Software Defined Networking)

• Networking devices have different functional
planes of operation
- Data, control, and management planes
• Split the functions into separate logical units
- Extend the functionality and management
of a single device
- Perfectly built for the cloud
• Infrastructure layer / Data plane
- Process the network frames and packets
- Forwarding, trunking, encrypting, NAT
• Control layer / Control plane
- Manages the actions of the data plane
- Routing tables, session tables, NAT tables
- Dynamic routing protocol updates
• Application layer / Management plane
- Configure and manage the device
- SSH, browser, API