Wireless Networks Summaries
#mnemonics
- CSMA/CA (Carrier Sense Multi-Access with Collision Avoidance) is used to avoid collisions in wireless networks (like CSMA/CD in wired networks)
- WPA Authentication Modes
- PSK = Personal
- 802.1X = Enterprise
- WLC Trivia
- When creating Interfaces, you first Name the interface, then assign a VLAN ID
- When mapping a WLAN to a VLAN, you're asked for these properties in order:
- Type
- Profile Name
- Used to identify the WLAN on the WLC
- Usually the same as the SSID
- SSID
- ID
- Unique number that identifies the WLAN in the WLC
- Specific number or order doesn't matter
- Automatically increments
- Enable WPA+WPA2 PSK Authentication
-
- WLAN Tab>Edit WLAN
- Security Subtab>Layer 2 Subtab
- Choose WPA+WPA2
- Check the box for WPA2 Policy
- VLAN QoS
- Platinum = Voice
- Gold = Video
- Silver = Best Effort, default
- Bronze = Background
Wireless Signal Disruption
- ARRDSI
- Absorption
- Signal is absorbed in material and converted to heat
- Reflection
- Signal bounces off material
- Refraction
- When the wave is broken up because it's slowed down by the medium it's passing through
- Refraction, literally "to break up"
- Diffraction
- When a signal is split around an object, creating a blindspot
- Diffraction, literally "to break apart"
- Scattering
- Physical interference, like dust, smog, uneven surfaces, etc.
- Interference
- Signal interference, like other WLAN connections, microwaves, etc.
Wireless Signal Anatomy
- FAPH
- Amplitude
- The size of each cycle/oscillation in a wave
- Period
- The time it takes for one cycle/oscillation to take place.
- The Period is the reciprocal of the Frequency
- Frequency
- The number of cycles/oscillations per unit of time.
- The Frequency is the reciprocal of the Period
- Hertz
- Cycles per second
- The unit of measurement for Frequency
- kHz = 1,000 cycles per second
- GHz = 1,000,000,000 cycles per second
- In 2.4GHz Wifi, there are 13 (technically 14) channels available
- Each channel is 22 MHz wide
- Avoid overlapping channels by choosing channels 1, 6, and 11
OSI or TCP/IP Layer
CCNA Exam Topic
#extop-2-9 #extop-2-6
Contributors
Sources