Ccna 3, Chapter 4

.05 miles

up to 300m (0.18 mile)

up to 30 miles (50 km)

an alternative to cable and DSL communication

broadband which uses a directional satellite dish that is aligned with a specific geostationary Earth orbit satellite.

International Telecommunication Union-radiocommuniction sector

a range of frequencies

2.4 GHz

UHF

SHF

EHF

WLAN

Bluetooth

Cellular broadcast

5 GHz WLAN

Microwave communication

Satellite communication

60 GHz WiGig WLAN

Radar landing systems

802.11

2.4 GHz

up to 2 Mb/s

5 GHz

up to 54 Mb/s

Since it transmits at 5 GHz, the higher frequency has a smaller coverage area and is less effective

2.4 GHz

11 Mb/s

2.4 GHz

54 Mb/s

dual band device, both 2.4 and 5 GHz

range from 150 Mb

.5 mile

multiple input multiple output

WiGig

2.4GHz, 5 GHz, 60 GHz

up to 7 Gb/s

60 GHz needs line of sight, when roaming device switches to lower 2.4 and 5 GHz bands

ITU-R

IEEE

WI-FI Alliance

Regulates the allocation of the RF spectrum and satellite orbits

specifies how RF is modulated to carry information

maintains standards for local and metro networks

promotes growth and acceptance of WLANs. Objective is to improve interoperability of products based on 802.11 by certifying vendors who conform to this standard

simplifies device connections

shares media between devices

simplify securely connecting to wifi hotspot networks

display video between devices

No boundary limits

unprotected from outside signals

same challenges as other wave based tech

rf bands regulated differently in different countries

the data frames are available for anyone to grab them.

other devices using the same or similar rf can interfere with the WLAN signal

as the signal travels further, it degrades and is lost

radio transmitter/reciever

required software driver for operation

access point

switch

router

service set identifier

standalone devices configured using cli or gui.

in situations where only a couple of APs are required in the network.

Server-dependent devices that require no initial configuration.

where there are many APs required in a network

Intro-level small business AP

Configured using GUI

Powered with AC or PoE

Mid level small business AP

configured/managed using gui/cli

supports clustering with single point setup

powered with AC or PoE

Mid-level small business AP

Configured with gui

Supports controller-less clustering technology

Powered using AC or PoE

clustering mode enabled on both

all have same cluster name

connected on same network segment

use same radio mode (ie 802.11n)

APs are managed centrally from a controller in the cloud

controller pushes management settings, security settings, wireless network and SSID settings to the various Meraki APs

omnidirectional

directional

yagi

provides stronger signal strength in one direction

directional antenna that can be used for long distance wifi networking

4

802.11 nic

access point

wireless router

ad hoc mode

infrastructure mode

when 2 devices connect wirelessly withough the aid of an infrastructure device such as a router or ap

bluetooth

wifi direct

when wireless clients interconnect via a wireless router or ap

basic service set

extended service set

basic service set

a single ap interconnecting all associated wireless clients

basic service area

bss=topology

bsa=actual coverage area

basic service set identifier

layer 2 mac address of the ap

extended service set

a union of 2 or more bss interconnected by a wired ds

clients in one bsa can communicate with clients in another bsa. can move from bsa to bsa if in the same ess and still connect

identifies type of wireless frame and contains subfields for protocol version, frame type, address type, power management and security settings

used to indicate remaining duration needed to receive the next frame transmission

contains the mac address of the receiving wireless device or ap

contains the mac address of the transmitting wireless device or ap

cometimes contains the mac address of the destination such as the router interface to which the ap is attached

contains sequence number and fragment number subfields

indicates the sequence of each frame

# of each frame sent of a fragmented frame

usually missing because it is used only in ad hoc mode

contains data for transmission

frame check sequence, used for layer 2 error control

provides current version of 802.11 protocol used

determines function of the frame, control, data or management

indicates whether frame is going to or exiting from the DS, only used in data frames of wireless clients associated with ap

indicates whether more fragments of the frame, either data or management type are to follow

indicates whether or not the frame or is being transmitted

indicates whether the sending device is in active mode or power save mode

indicates to a device in power-save mode that the ap has more frames to send

indicates whether encryption and authentiation are used in the frame

can indicate that all received data frames must be processed in order

management

control

data

used in the maintenance of communication such as finding, authenticating and associating the ap

used to facilitate in the exchange of data frames between wireless clients

used to carry payload info such as web pages and files

0x00

enables the ap to allocate resource and synchronize

device sends info about the wireless connection including supported data rates and ssid of the network to the ap. if request is accepted, connection is established

0x02

device sends it out when it drops from range of the currently associated ap and finds another ap with a stronger signal

0x03

0x01

sent from ap to wireless accepting association request

sent from ap contains the acceptance or rejection to a device reassociation request frameframe

0x04

sent from a wireless client when it requires information from another wireless client

0x05

sent from an ap containing capability information, such as supported data rates, after receiving probe request frame

0x08

sent periodically from an ap to announce its presence, hello frame

0x0A

sent from a device wanting to terminate a connection.

relinquish memory allocation and remove the device from the association table

0x0B

sending device to ap containing its identity

0x0C

sent from client wanting to terminate from another wireless client

used to manage the info exchange between a wireless client and an ap

help prevent collisions from occurring on the wireless medium

provide optional collision reduction for aps with hidden wireless clients

client sends rts in first step of 2-way handshake

request to send

clear to send

provides clearance for the requesting wireless client to send a data frame including a time value

minimizes the chance that other wireless clients will transmit while the requesting client transmits

sent by the client after receiving an error free frame from ap. if no ack sent by a certain time, ap resends frame

power management

frame type

security

protocol version

fromDS

distributed coordination function

write out sequence

network mode

ssid

channel setting

security mode

encryption

password

802.11 wlan standards

unique identifier that wireless clients use to distinguish between multiple wireless networks in the same vicinity. HOME-A552 for our house wifi

frequency bands used to transmit wireless data

refers to the security parameter settings such as WEP, WPA or WPA2

WPA2 personal

ap openly advertises its services by periodically sending broadcast beacon frames. allows clients to choose which network and ap to use

wireless clients must know the name of the ssid. client sends out a wireless probe request on multiple channels which include the ssid.

open authentication

shared key

provides wireless connectivity to any wireless device and should only be used in situations where security is of no concern

based on a key that is pre-shared between the client and the ap

finalizes settings and establishes the data link between the wireless client and the ap

association identifier

logical port that the ap maps to keep track of frames destined for the clients.

allocation of frequency sections

degrades the quality of the communication

direct-sequence spread spectrum

a spread-spectrum modulation technique designed to spread a signal over a larger frequency band making it more resistant to interference.

crafted noise added to the user signal and known by the receiver to amplify the signal

frequency-hopping spread spectrum

hops carrier signals among many frequency channels to prevent congestion and have a more efficient use of the channels

orthogonal frequency-division multiplexing

a subset of frequency division multiplexing in which a single channel utilizes multiple sub-channels on adjacent frequencies which are orthogonal to one another.

microwave

802.11b

802.11g

802.11n

802.11ad

802.11a

802.11n

802.11ac

802.11ad

802.11ad

22 MHz

5 MHz

1

6

11

use channel bonding which takes 2 20 Mhz channels and combines them into 1 40 MHz channel. Uses both channels at same time to delivery data

geographical layout of the space

# of bodies and devices in that space

data rates users expect

use of non-overlapping channels by multiple AP

transmit power settings

If APs are to use existing wires or if new wires have to be placed

Position APs above obstructions

Position APs vertically near the ceiling in the center of coverage area if possible

Position APs in locations where users are expected to be

comverage area provided by a single channel

mixed mode

basic service set (bss)

extended service set

beacons

unauthorized aps installed by a well-intentioned user or willingly for malicious purpose.

unauthorized users attempting to access network resources.

use wireless management software

deter intruders using authentication

data that can be easily captured

use encryption

improperly configured devices

Malicious user

Accidental interferance

harden all devices

keep passwords secure

create backups

ensure all configuration changes occur off hours

they manipulate the management frames to consume ap resources and keep channels too busy to service legitimate user traffic.

spoofed disconnect attack

cts flood

an attacker sends a series of disassociate commands to all wireless clients within a bss.

attacker repeatedly floods the bss with clear to send frames to a bogus client.

connected to a corporate network without explicit authorization against policy

connected to capture client data such as mac addresses, capture/disguise data packets or start man in the middle attacks

a user with secure network access could enable unauthorized users access to network through unsecured hot spot

use monitoring software to monitor the radio spectrum for unauthorized aps

attacker introduces a rogue ap and configures it with the same ssid as a legitamate ap.

ssid cloaking

mac address filtering

aps and some wireless routers allow the ssid beacon frame to be disabled. clients must manually identify the ssid to connect to the network

admin can manually allow or deny clients wireless access based on their physical mac hardware address

open system authentication

shared key authentication

any wireless client should be easily able to connect. should only be used in no security concern situations

provides mechanisms such as WEP, WPA or WPA2 to authenticate and encrypt data between client and ap.

original 802.11 specification , data secured using RC4 encryption method with static key which makes it easy to hack

wifi alliance standard uses much stronger temporal key integrity protocol encryption algorithm

temporal key integrity protocol

IEEE 802.11i industry standard for securing wireless networks, uses advanced encryption standard for encryption

advanced encryption standard

Pre-shared key

RC4

CRC-32

weak

PSK or 802.1x

TKIP

MIC

Strong

PSK or 802.1x

AES

it makes use of wep but encrypts the layer 2 payload using tkip and carries out a message check to make sure that packets are not tampered with.

ccmp protocol

counter cipher mode with block chaining message authentication code protocol

recognize if the encrypted and non-encrypted bits have been tampered with

personal

enterprise

users authenticate using a pre-shared key or pre-shared password, no special server is required

requires a RADIUS server, users must authenticate using 802.1x standard which uses eap

remote authentication dial in user service

extensible authentication protocol

provides a secure authentication mechanism and negotiates a secure private key that can be used for wireless encryption session using tkip or aes encryption

internet connection

dhcp settings

ssid name

wlan security

management access