Study Session Number 35! Wireless Networking #36

Need to re-read/re-watch information on this topic mostly just for WLC configuration.

WAP's - 

Provide connectivity between wireless stations and the wireless & wired networks. Wireless is half duplex (CSMA/CA).

Wireless Network Types -

WPAN (Personal Area Network) - Devices within 10 meters of each other. Bluetooth is used. 

WLAN (Local Area Network) - Devices within 100 meters of AP. 

WMAN (Metropolitan Area Network) - Covers large areas such as cities. 

AD-Hoc - 

Peer to peer device connectivity, peer to peer network known as Independent Basic Service Set (IBSS).

Infrastructure Mode - 

Rather than an AD-Hoc network where the clients communicate directly with each other, infrastructure mode uses a wireless access point (Access Point) and the clients communicate through the AP. AP can be connected to the wired network to solve scalability issues that AD-Hoc networks have OR use multiple AP's to increase network coverage. 

Infrastructure Mode Terminology - 

• Basic Service Set (BSS)
• Distribution System (DS).
• BSSID
• Basic Service Area (BSA).
• SSID
• ESS

When the devices connect to the WAP this creates a Basic Service Set (BSS).

The device that the WAP is plugged into (switch, router etc) is called the Distribution System (DS).

Devices within the BSS are identified with there BSSID (which is based off of the devices MAC address).

The wireless coverage of the AP is called the Basic Service Area (BSA).

SSID = The name of the device when searching for it to connect to. One AP may have multiple SSID names, for instance one for HR and another for Sales each with there own individual security rules and mapped to separate VLAN's. Requires Username and Password, this is how the vlan and security rules are then applied to the specific user. ESS is an extension of SSID in that it uses the same SSID across multiple WAP's to increase coverage, different wireless channels are used to avoid interference. 

Beacons - WAP's broadcast information about there WLAN's (including SSID and authentication requirements) with beacon frames, these can be disabled for security.

Roaming is when one client devices roams from one area to another, connecting from the original AP to a different one. 

WiFi Direct - 

Allows a mix of Infrastructure Mode and AD-Hoc mode to work together at the same time. Devices can connect to an AP (Infrastructure Mode) and also connect to the peer to peer network (AD-Hoc - doesn't use IBBS mode). Is a WPAN network.

Wireless Bridge - 

Used where cable connectivity isn't possible to extend the signal to the next device eg WAP.

Wireless LAN Controllers (WLC) -

Used to manage AP's from a central location, access points that are configured and controlled by the WLC are called Lightweight AP's, the software within the AP is what determines if the AP is a Lightweight or a Autonomous AP. Can be used to monitor the quality and power of each individual access point. Can detect rouge AP's. Split MAC is used to take some of the workoad of the AP's and give it to the WLC, this is why the AP's are called lightweight AP's. doing this increases the performance of the AP's as they dont have as much workload to deal with. 

CAPWAP (Control and Provisioning of wireless access points) - 

This is the protocol that is used to allow the wireless lan controller the ability to be able to manage the WAP's. Communications are encrypted. UDP Ports 5246 & 5247. 

WLC Zero Touch Provisioning (ZTP) - 

Used to discover WLC then downloads its configuration (this includes what it should support). Can discover WLC through - DHCP/Local Subnet broadcast/DNS (Resolves IP the IP of the WLC). 

WiFi Spectrum - 

2.4GHz - 5GHz - allocated for ISM (Industrial, Scientific & Medical).

WiFi Standards -

802.11a - 2.4GHz 

802.11b - 5GHz

802.11g - 2.4GHz

802.11n - 2.4GHz - 5GHz

802.11ac - 5GHz

NOTE:CHANNELS - 1, 6, 11 DONT OVERLAP WITH EACH OTHER IN 2.4GHZ

NOTE:CISCO AP's SUPPORT ALL STANDARDS.

2.4GHZ v 5GHz -

2.4 Has better distance and better propagation through obsticles.

2.4 is more crowded due to it being an unlicensed band.

5 supports 802.11ac which has higher throughput than is available with 2.4

Clients may only support 2.4 as its older so more common.

Wireless Security - 

WEP (Wired Equivelent Privacy) - RC4 Encryption 

WPA (WiFi Protected Access) - RC4 Encryption, TKIP (Temporal Key Integrity Protocol)

WPA2 (WiFi Protected Access2) - DES Encryption, CCMP (Counter Cipher Mode) 

WPA3 (WiFi Protected Access3) - DES Encryption, CCMP, protection to KRACK attack.

WPA Personal - Uses Pre-Shared Keys (PSKs)

WPA Enterprise - uses a AAA server (RAIDUS + 802.1X).