Network Devices Flashcards
What Do Routers Do?
Routes traffic between IP subnets
– Makes forwarding decisions based on IP address
– Routers inside of switches sometimes called
“layer 3 switches”
What are 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
What Do Unmanaged Switches Do?
- 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
What Do Managed Switches Do?
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
POE Switch
- Power over Ethernet
– Commonly marked on the switch or interfaces
- 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
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
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
802.11a
Operates in the 5 GHz range
– Or other frequencies with special licensing
* 54 megabits per second (Mbit/s)
* Smaller range than 802.11b
– Higher frequency is absorbed by objects in the way
* Not commonly seen today
802.11b
Operates in the 2.4 GHz range
11 megabits per second (Mbit/s)
802.11g
Operates in the 2.4 GHz range
* 54 megabits per second (Mbit/s) - Similar to 802.11a
* Backwards-compatible with 802.11b
* Same 2.4 GHz frequency conflict problems as 802.11b
