Wireless Networking Fundamentals Flashcards
WPAN
Wireless Personal Area Network:
Devices are within 10 meters of each other
Example: Bluetooth
WLAN
Wireless Local Area Network:
Provides access to a campus (typically wired) network, without the need for a cable
Devices within 100m of WAP
WMAN
Wireless Metropolitan Area Network:
Covers a large area (example: city)
Ad Hoc Networks
Peer-to-peer
2+ wireless stations communicate directly
IBSS (Independent Basic Service Set)
Infrastructure Mode
Stations communicate via AP
Multiple APs can be deployed
Wifi Direct
Allows devices to be connected to an AP & also be part of peer-to-peer wireless network
Does not operate in Ad Hoc
– It’s an extension to infrastructure mode
WPS (Wifi Protected Setup) enables connection setup by pushing a button
WPAN
Predefined Services
—Miracast to wireless external monitor
—DLNA (Digital Living Network Alliance) allows devices to stream music/video
—Direct Print
Wireless Bridges
Can be used to connect areas not reachable via cable to the network
Mesh Networks
One AP radio is used to serve clients
The other radio connects to the backhaul network
WAPs
Wireless Access Points:
Provide connectivity between wireless stations & between wired/wireless networks
Wireless is Half-duplex
—Only one device can communicate at a time
BSS
Basic Service Set:
An AP centralizes access & control over a group of wireless devices
The devices & their wireless settings make up a BSS
DS
Distribution System:
Connects WAPs to the wired network
BSSID
Basic Service Set Identifier:
Devices within BSSs are identified by BSSID which is based on their MAC
BSA
Basic Service Area:
AKA: Wireless Cell
The wireless coverage area of an AP
SSID
Service Set Identifier:
Unique wireless network name
Multiple SSID:
–A single AP can support multiple SSIDs
—-Ex: “Corporate” & “Guest”
–Different SSIDs can have different security settings & mapped to different VLANs
Beacons
WAPs broadcast info about their WLANs with beacon frames
Can be disabled
ESS
Extended Service Set:
The same SSID can be supported across multiple APs to give a larger coverage area
Roaming
Wireless client stations can roam across APs supporting the same WLANs
WLC
Wireless LAN Controller:
In a large campus, configuring a large amount of APs one by one becomes unmanageable
Can be physical or virtual
The WLC also monitors the wireless quality & controls the channels & power of the APs
—It can also detect rogue APs
Autonomous AP
Standalone APs
Lightweight AP
APs with a WLC
The LAP (Lightweight AP) downloads its configuration from the WLC
—This includes what WLANs it should support & their settings
Zero Touch Provisioning
Gives the ability to install a network appliance somewhere without requiring local configuration
Lightweight APs support this
They discover their WLC via:
—DHCP - option 43 gives the IP of the WLC
—DNS - “cisco-capwap-controller” resolves the IP of the WLC
—Local subnet broadcast
CAPWAP
(and port numbers)
Control and Provisioning of Wireless Access Points:
Open standard that enables WLCs to manage a collection of WAPs
Communications are encrypted inside a DTLS CAPWAP tunnel
Uses UDP ports 5246 & 5247
Split MAC
Work is moved from the APs to the WLC which is why they are called LAPs
Real-Time traffic is still handled by the AP in order to provide suitable performance
—The rest is handled by the WLC
AP vs. WLC Operations
AP Operations:
—Client handshake when connecting
—Beacons
—Performance monitoring
—Encryption/decryption
—Clients in power save
WLC Operations:
—Authentication
—Roaming control
—802.11 to 802.3 communication
—Radio frequency management
—Security management
—QoS management
Traffic Flow with CAPWAP
Please refer to the diagram in the study guide
Management traffic between the AP & WLC also passes through the CAPWAP tunnel
LAG (Etherchannel) is often used on the WLC to switch link
FlexConnect
Traffic is forwarded locally when FlexConnect is configured
–Useful for small branch offices without a WLC
Switch Configuration for Wireless Networks: Autonomous AP (includes commands)
–Create VLANs (global config):
vlan 21
name Corporate
vlan 22
name Guest
–Configure Trunk between AP & Switch:
interface g1/0/1
switchport trunk encap dot1q
switchport mode trunk
switchport trunk allowed vlan 21,22
Switch Configuration for Wireless Networks: CAPWAP (includes commands)
Link between switch and WLC is configured as trunk
Link between AP & switch is configured as access
–Create VLANs:
vlan 21
name Corporate
vlan 22
name Guest
–Create Management VLANs:
vlan 10
name WLC-Management
vlan 11
name AP-Management
–Configure Switch Port for WLC:
interface g1/0/2
switchport trunk encap dot1q
switchport mode trunk
switchport trunk allowed vlan 10,11,21,22
–Configure Switch Port for AP:
interface g1/0/1
switchport mode access
switchport access vlan 11
802.11
1997
Up to 2Mbps
2.4GHz band
802.11a
1999
up to 54Mbps
5GHz band
802.11b
1999
Up to 11 Mbps
2.4GHz band
802.11g
2003
up to 54 Mbps
2.4GHz band
Backward compatible with b
802.11n
2009
Up to 600 Mbps
2.4 & 5 GHz band
Backward compatible with a, b, g
802.11ac
2013
Up to 3500 Mbps
5GHz band
Backward compatible with a & n
2.4 GHz Spectrum
Ranges from 2.4 to 2.4835 GHz
—2.4 to 2.497 in Japan
Divided into smaller (22 MHz) ranges of frequencies called channels
5 GHz Spectrum
Channels are 20 MHz wide
Less overlap than 2.4 GHz channels
Neighboring APs should be separated by at least one channel
Channels can be bonded (40, 80, or 160 MHz wide) to multiply data rates by 2, 4 or 8x
2.4 GHz Interference
The ISM band is unlicensed
Many devices also use this frequency band and can cause interference
2.4 vs. 5 GHz
2.4 GHz has greater range & propagation through obstacles
2.4 GHz is more crowded
5 GHz 802.11ac has higher throughput than is available with 2.4 GHz
Your client stations may only be compatible with 2.4 GHz
Site Surveys
Help to find the best placement for APs for max coverage & minimum leakage
Should also discover potential sources of interference
A WLC can manage channel allocation & power levels of APs
Wireless Security Protocols
WEP
1999 - RC4 encryption
WPA
2003 - RC4 encryption; TKIP
WPA2
2004 - AES encryption, CCMP
WPA3
2018 - AES encryption, CCMP, protection against KRACK attack
WPA Personal vs. Enterprise
Personal - uses PSKs (pre-shared keys)
Enterprise - uses AAA