Chapter 7,

Question 1

What is a station?

Answer 1

The wireless client.

Question 2

What are service sets?

Answer 2

Describes how radios may be used to communicate with each other.

Question 3

What is a simplex transmission and provide an example?

Answer 3

A simplex communication, one device is capable of only transmitting, and the other device can only receive.

FM radio is a good example.

Question 4

What is a thin Access Point?

Answer 4

With thin access points, the AP configuration and intelligence resides inside a WLAN controller

Question 5

What does it mean when a station is associated?

Answer 5

Has layer 2 connection (authenticated and associated) with an access point.

Question 6

What is the MSDU?

Answer 6

The payload of a wireless 802.11 data frame is the layer 3–7 information.

Question 7

Define what the 802.11-2012 integration service (IS) integration is? Why is it important?

Answer 7

This describes the delivery and transfer of MSDU’s between the RF medium and the 802.3 wired network.

This is important Because the wired infrastructure is a different physical medium, an 802.11 data frame payload must be effectively transferred into an 802.3 Ethernet frame.

Question 8

Give an example of an integration service using a VoWiFi phone.

Answer 8

A VoWiFi phone sends an 802.11 data frame to a standalone access point. The MSDU payload of the frame is a VoIP packet with a final destination of an IP PBX that resides at the 802.3 network core. The integration service removed the 802.11 header and trailer and then encases the MSDU VoIP payload inside an 802.3 frame. Reverse is done.

Question 9

What is a Distribution System medium? Give an example.

Answer 9

A logical physical medium used to connect access points. The most common example is an 802.3 medium.

Question 10

What is a Distribution System Service? What does this service do in junction with the Integration Service?

Answer 10

System services built inside an access point are usually in the form of software. The DSS provide the switch like intelligence. These software services are used to manage client station associates, associations, and dissociations.

This works in tandem with the integration service because Distribution System Services also use the layer 2 addressing of the 802.11 MAC header to eventually forward the layer 3–7 information (MSDU) either to the integration service or to another wireless client station.

Question 11

What is a Wireless Distribution System? Give 2 examples.

Answer 11

This is the same as a distribution system medium on 802.3 however this time its the wireless network.
An example would be a mesh network.
Another example would be a wireless repeater.

Question 12

What are the 4 MAC addresses that are used in a frame when a wireless distributed network is used?

Answer 12

a frame sent within any type of WDS requires four MAC addresses: a source address, a destination address, a transmitter address, and a receiver address.

Question 13

Do wireless repeaters and the AP have to be on the same channel?

Answer 13

Yes, because it effectively increases the cell.

Question 14

What is an SSID?

Answer 14

It is a logical name used to identify an 802.11 wireless network. It is also used for AP’s to identify each other.

Question 15

How many characters can an SSID have? Is it case sensitive?

Answer 15

32 characters and yes it is case sensitive,

Question 16

What is a basic service set?

Answer 16

Consist of one AP radio with one or more client

stations.

Question 17

What is a BSSID?

Answer 17

The layer 2 identifier of each individual BSS. The radio’s MAC address. Most often the BSSID is the
MAC address of the radio network interface.

Question 18

Name 3 purposes for the BSSID

Answer 18

1. The BSSID address plays a role in directing 802.11 traffic within the basic service set.
2. This address is also used as a unique layer 2 identifier of the basic service set.
3. Furthermore, the BSSID address is needed during the roaming process.

Question 19

What is a basic service area? How does RSSI come into play with this?

Answer 19

The physical area of coverage provided by an access point in a BSS.

Client stations can move throughout the coverage area and maintain communications with the AP as long as the received signal strength between the radios remains above received signal strength indicator (RSSI) thresholds.

Question 20

What is an extended service set?

Answer 20

An extended service set is two or more basic service sets connected by a distribution system medium. Usually an
extended service set is a collection of multiple access points and their associated client stations, all united by a single DSM.

Question 21

What is nomadic roaming?

Answer 21

When a client leaves a BSS that isn’t overlapping with another BSS. The client loses connectivity, That small window of time that occurs between the client moving between BSS is called nomadic roaming.

Question 22

What is co-location?

Answer 22

When a BSS overlaps heavily with another BSS on a different channel. This is designed to provide capacity.

Question 23

What is an independent basic service set? Explain in detail.

Answer 23

The radios that make up an IBSS network consist solely of client stations (STAs), and no access point is deployed. All of the stations transmit frames to each other directly and do not route their frames from one client to another. All client station frame exchanges in an IBSS are peer to peer. All stations in an IBSS must contend for the half-duplex medium, and at any given time only one STA can be transmitting.

Question 24

What is a mesh basic service set?

Answer 24

Set of APs that provide mesh distribution.

Question 25

What is a mesh point portal, or MPP?

Answer 25

one or more mesh APs that are typically connected to the wired infrastructure.

Question 26

What are mesh points?

Answer 26

Mesh APs that are not connected to a wired infrastructure.

Question 27

What is a hybrid wireless mesh protocol ?

Answer 27

Because routing on an AP mesh network is all layer 2 routing using radio MAC addresses, all mesh networks have to have at least one mesh AP connect to an 802.3 network. The mesh protocol is a routing protocol designed for mesh networks that allow mesh points to decide the best route for forwarded frames to take.

Question 28

What is a RAP (Root AP)?

Answer 28

The main purpose of a RAP is to serve as a portal to a distribution system. The normal default
setting of an AP is root mode, which allows the AP to transfer data back and forth between
the DS and the 802.11 wireless medium.

Question 29

What are 2 other common terms that vendors use for root mode?

Answer 29

Access Mode and AP mode.

Question 30

What does it mean when an AP is in bridge mode?

Answer 30

The AP radio is converted into a wireless bridge. This typically adds extra MAC-layer intelligence to the device and gives the AP the capability to learn and maintain tables about MAC addresses from the wired side of the network.

Question 31

What does it mean when an AP is in workgroup bridge mode?

Answer 31

The AP radio is transformed into a workgroup bridge which provides wireless backhaul for connected 802.3 wired clients.

Question 32

What does it mean when an AP is in repeater mode?

Answer 32

The AP radio performs as a repeater AP which extends the coverage area of a portal AP on the same channel.

Question 33

What does it mean when an AP is in Mesh Mode?

Answer 33

The AP radio operates as a wireless backhaul radio for a mesh environment. Depending on the vendor, the backhaul radio may also allow for client access.

Question 34

What does it mean when an AP is in scanner mode?

Answer 34

The AP radio is converted into a sensor radio, allowing the AP to integrate into a wireless intrusion detection system (WIDS) architecture. An AP in scanner mode is in a continuous listening state while hopping between multiple channels. Scanner mode is also often referred to as monitor mode.

Question 35

What does it mean when an AP is in infrastructure mode?

Answer 35

When running in Infrastructure mode, the client station will allow communication via an access point. Infrastructure mode allows for a client station to participate in a basic service set or an extended service set. Clients that are configured in this mode may communicate, via the AP, with other wireless client stations within a BSS