| Wireless Principles ? | - So, what happens in the wireless world?
- Electro-Magnetic field to encode data (0,1)
- Encoding will be done by changing the frequency of a wave
- that is measured by Hertz
- and Hertz: the change in frequency/second
- then, Modulation will express the Zeros and Ones |
| Wi-Fi generation .. | - there are Wi-Fi generations (like Ethernet Categories)
- starts from 802.11a (2 Mbps) – 802.11ax (14 Gbps)
- will i really get a 14 Gbps!!!! Wirelessly!!!! (version 6)
no because that needs a Ideal conditions . |
| what is transceiver ? and what it does ? | - The Encoder now, the one who turns the Zeros and Ones
To that “Electro-Magnetic” field, is called a Trans/ceiver .
- The more transceivers available, the more data encoded
- Then, a transceiver, will push the field, through an Antenna
*also, the more antennas, the more data. |
| transceiver and antennas needs what to make them work ? | - To generate and push data through the air, there must a power to
Do so! So, a power source is also needed.
- this power source might be a battery or an AC adapter . |
| measuring the power of a frequency is called ? | “Amplitude” |
| what is Wireless Network Components ? | 1-Wi-Fi Client (End Point): also called a “Station” .
2- Wi-Fi Access Points (AP) .
3- Wi-Fi Controllers (optional ) . |
| what is stations ? | (End Point): also called a “Station”
- Generates/Consumes Data
- Have Transceivers (to encode data)
- Have Antennas (to push the data)
- It will need Power |
| what is AP ? | Wi-Fi Access Points (AP)
- GW for the stations
- Stations talks through the AP
- also have Transceivers
- also have Antennas |
| what is Wi-Fi Controllers ? | - Controls APs (central point of management)
- Controls Access for clients (AAA) |
| what is the 3 types of wifi networks ? | - Ad-Hoc
- Point to Point (NO APs), as Bluetooth and wifi direct in samsung devices.
- Infrastructure
- AP between stations
- Mesh
- APs talking together (Wirelessly), like when we have extenders in hotels . |
| what is (BSS) ? | Basic Service Set (BSS): A single AP and it’s coverage area |
| what is (BSSID) ? | Basic Service Set Identifier (BSSID): The MAC address of that AP . |
| what is (SSID) ? | Service Set Identifier (SSID): Name of the WLAN . |
| what is (DS)? | Distribution System (DS): The Wired Net. that connects the AP to the LAN |
| what is ESS ? | Extended Service Set (ESS): A collection of APs connected to the same
DS, offering the same WLAN & SSID (like hotels, hotspot) . |
| what is happening exactly between the transceivers? | - a group, or a range of Radio Frequencies (RF), are being
Established, all are encoding and transmitting data,
- each frequency can be modulated differently (for more encoding)
- the total RF bandwidth is then called (Channel Bandwidth)
- Channels include Frequencies, either from the 2.4 GHz range,
Or from the 5 GHz range
*channel bandwidth: the total bandwidth of the involved frequencies |
| 2.4 GHz channels issues ? | - if 2 channels were close enough, streaming some common frequencies,
overlapping will happen
- unless, they were far enough
- this is with 2.4 GHz channels only (which comes in 20 MHz width) |
| 5GHz channels advantages ? | - with 5 GHz channels, a new channel, start with a frequency, right after
The last channel’s frequency ended
- so, overlap won’t happen
- the 5 GHz channels support from 20 MHz width, up to 160 MHz! (by merging channels ).
*more channel width, means more frequencies included, thus, more data
Can be encoded. |
| what is the 3 types of WLAN Architectures ? | 1- Autonomous Architecture .
2- Split-MAC Architecture .
3- Cloud-Based Architecture .
4- Centralized WLAN Architecture .
5- Converged WLAN Architecture . |
| what is Autonomous Architecture ? | - Autonomous Architecture
- Autonomous (Independent) Access Points
- Independent Management (GUI)
- one or more SSIDs (each = 1 VLAN)
*when having multiple SSIDs, and each will be 1 VLAN, the back link
Should be a trunk
*adding a new SSID, requires to login to each AP individually |
| what is Split-MAC Architecture ? | - there is a WLC
- APs now will be called Lightweight APs (LAPs)
- WLCs will manage (RF, QoS, AAA, Policies)
- APs will (RF TX/RX of frames, RF Collision Detection,
MAC & Data Management) . |
| what is Cloud-Based Architecture ? | - also, a WLC
- but remotely (through public cloud, or private cloud)
- also, LAPs
- might be a Cisco Meraki (does self-config to the LAPs)
- or, Cisco Cat. 9800-CL |
| what is CAPWAP ? | *when having WLC & LAP scenario, there will be a private tunnel between them,
It will encapsulate and transfer all the control and data information between the
WLC and LAPs, it’s called the “Control and Provisioning of Wireless AP”
Or “CAPWAP” |
| what about control and data tunnel of CAPWAP ? | - 2 tunnels (control tunnel = UDP5246, data tunnel = UDP5247)
- control tunnel (encrypted and authenticated)
- data tunnel (not encrypted by default) |
| how many ways can we WLC Positioning ? | 2 ways :
- Centralized WLAN Architecture .
- Converged WLAN Architecture . |
| Centralized WLAN Architecture ? | - single WLC that controls all the LAPs
- might be placed in the DC, or near the edge of the network
- all data must pass through the CAPWAP tunnel to reach the WLC
- even if the destination is closer than the WLC |
| how can we fix this too long destination to transmit data ? | - this can be fixed, using Cisco Flex Connect
- which is a mode, to be enabled on the LAPs
- especially if the LAPs like in a branch, and the WLC is in the HQ
- LAPs can now pass the traffic directly to the LAN
- LAPs can now authenticate the clients for access
- LAPs can now work even if the CAPWAP tunnel goes down |
| what is Converged WLAN Architecture ? | - connect a WLC and an AP both, to the same switch.
- the access/distribution layer switch.
- now the LAPs are reaching the WLC through the switch.
- multiple WLCs will be needed in such scenario.
- this leads to a shorter distance CAPWAP.
- hence, faster Wi-Fi, less delays. |
| Cisco Catalyst 9300 series ? | *Cisco Catalyst 9300 series, provides switches, that can have a WLC
Integrated inside the switch itself (embedded) |
| what is AP Modes ? and how much they are ? | - Local Mode.
- Bridged Mode.
- Flex Connect Mode .
- Monitor Mode.
- Sniffer Mode.
- Sensor Mode.
- Mesh Mode . |
| local mode ? | Local Mode
- the default of a LAP
- CAPWAP to the WLC
- everything passes through the CAPWAP
- if the CAPWAP fails, all clients will be disconnected |
| Bridged Mode ? | - allows an Autonomous AP to connect as a client
To the LAP |
| Monitor Mode? | Monitor Mode
- generates reports & statistics, send them to the WLC . |
| Sniffer Mode ? | - scan a specific channel
- send the scanning reports to the WLC |
| Sensor Mode ? | - perform SSID tests
- send test report to the DNA Center |
| Mesh Mode ? | *a frame might travel multiple mesh nodes before reaching the LAN
*a mesh node (MAP), uses adaptive wireless path protocol (AWPP)
To determine the best path to a root node/AP (RAP) |
| how to bundle/aggregate ports ? | - WLC: use “channel-group mode on” on the switch, as it doesn’t
Support LACP/PAgP.
- AP: either using “ON” or “LACP”, BUT, only with “local” APs,
Not the “Autonomous” APs. |
| what WLAN should have to be secure ? | - Unsecured WLANs are the once with no password, free, and public
- Secured WLANs might have:
- hidden SSID
- Authentication
- Encrypt Data (from the client to the AP) |
| Authentication can be done by what ? | - authenticating the user’s credentials.
- authenticating a device’s MAC Address.
- captive portal. |
| how Encryption works ? | - for data frames only
- Management frames won’t get encrypted
- happens between client and AP only
- what’s beyond AP (the LAN) is not encrypted |
| how to have an end to end encryption ? | - use HTTPS
- that will send a digital certificate between the src and dst
- thus, the entire path will be encrypted |
| what is WPA ? | Wi-Fi Protected Access (WPA)
- has 2 types (Personal and Enterprise) |
| personal WPA ? | Personal:
- uses a passphrase (statically assigned password in the AP)
- uses a 256-bit pre-shared key for encryption
- this pre-shared key is derived mathematically
From the passphrase
- this pre-shared key utilizes RC4 + TKIP, and MIC
For generating the pre-shared key
- TKIP every packet with a unique key! |
| Enterprise WPA ? | uses 802.1X (supplicant, authenticator, authentication Server)
- packets carried by EAP
- 802.1X will happen only between the supplicant and the
Authenticator
- the rest (authenticator, to the authentication server)
Will be RADIUS, after the authentication is done, comes the encryption
,encryption is done by the authentication server.
- which will give each client, a unique key. |
| WPA2 ? | the same of WPA with some different :
- Personal:
supports AES-CCMP, and, RC4+TKIP .
-Enterprise:
- 802.1X in Ad-Hoc mode (ignore that).
- 802.1X supports re-authentication (faster). |
| WPA3 ? | - personal and enterprise modes are here
- it supports “Enhanced Open” Wi-Fi (like airports)
- it supports “Wi-Fi Easy Connect” (for IoT) |
| Personal WPA3 ? | - no pre-shared key
- SAE instead
- the derived key now is not related to the passphrase
- protects against offline dictionary attacks
- uses “Protocol Management Frame” (PMF)
- encrypt some Management Frames |
| Enterprise WPA3? | - Enterprise
- uses PMF
- uses 192-bit minimum cryptographic security suite |
