5.5 Wireless Networking

Question 1

WIRELESS NETWORKING

Answer 1

Wireless networking is a way to network without wires.

Question 2

IEEE 802.1

Answer 2

The most common specifications for how wireless networking devices should communicate are defined by the IEEE 802.11 standards.
This set of specifications, also called the 802.11 family make-up the set of technologies we call Wi-Fi.

The most common specifications you might run into are:
802.11b
802.11a
802.11g
802.11n
802.11ac.

In terms of our networking model, you should think of 802.11 protocols as defining how we operate at both the physical and the data link layers.

Question 3

FREQUENCY BAND

Answer 3

A frequency band is a certain section of the radio spectrum that’s been agreed upon to be used for certain communications.

Wi-Fi networks operate on a few different frequency bands, most commonly the 2.4 gigahertz and 5 gigahertz bands.

Question 4

802.11 FRAME

Answer 4

An 802.11 frame has a number of fields:

1 FRAME CONTROL FIELD
2 DURATION FIELD
3 SOURCE ADDRESS FIELD
4 INTENDED DESTINATION FIELD
5 RECEIVER ADDRESS
6 SEQUENCE CONTROL FIELD
7 TRANSMITTER ADDRESS
8 DATA PAYLOAD
9 FRAME CHECK SEQUENCE

Question 5

1 FRAME CONTROL FIELD

Answer 5

Is 16 bits long and contains a number of sub-fields that are used to describe how the frame itself should be processed.

Question 6

2 DURATION FIELD

Answer 6

It specifies how long the total frame is. The receiver knows how long it should expect to have to listen to the transmission.

Question 7

3 SOURCE ADDRESS FIELD

Answer 7

Represents the MAC address of the sending device.

Question 8

WIRELESS ACCESS POINT

Answer 8

Is a device that bridges the wireless and wired portions of a network.

Question 9

4 INTENDED DESTINATION FIELD

Question 10

5 RECEIVER ADDRESS

Answer 10

The MAC address of the access point that should receive the frame.

Question 11

7 TRANSMITTER ADDRESS

Answer 11

The MAC address of whatever has just transmitted the frame.

Question 12

6 SEQUENCE CONTROL FIELD

Answer 12

Is 16 bits long and mainly contains a sequence number used to keep track of ordering the frames

Question 13

8 DATA PAYLOAD

Answer 13

Has all of the data of the protocols further up the stack.

Question 14

9 FRAME CHECK SEQUENCE

Answer 14

Contains a checksum used for a cyclical redundancy check.

Question 15

AD-HOC NETWORKS

Answer 15

Nodes all speak directly to each other.

In an ad-hoc network, there isn’t really any supporting network infrastructure.

Question 16

WIRELESS LANS or WLANS

Answer 16

One or more access points act as a bridge between a wireless and a wired network.

The wired LAN contains the outbound Internet link. In order to access resources outside of the WLAN, wireless devices would communicate with access points. They then forward traffic along to the gateway router where everything proceeds like normal.

Question 17

MESH NETWORKS

Answer 17

Are a hybrid of the two.

This network lets you deploy more access points to the mesh without having to run a cable to each of them. With this setup, you can really increase the performance and range of a wireless network.

Question 18

CHANNELS

Answer 18

Channels are individual, smaller sections of the overall frequency band used by a wireless network.

Question 19

WEP

Answer 19

WEP stands for Wired Equivalent Privacy and it’s an encryption technology that provides a very low level of privacy.

WEP only uses 40 bits for its encryption key.

Question 20

WPA

Answer 20

WPA or Wifi Protected Access.

WPA by default uses a 128-bit key, making it a whole lot more difficult to crack than WEP.

Question 21

WPA2

Answer 21

An update to the original WPA.

WPA2 uses a 256 bit key.

Question 22

MAC FILTERING

Answer 22

With MAC filtering, you configure your access points to only allow for connections from a specific set of MAC addresses belonging to devices you trust.

Question 23

CELLULAR NETWORKING

Answer 23

Cellular networking operates over radio waves and there are specific frequency bands specifically reserved for cellular transmissions.

Cellular networks are built around the concept of cells. Each cell is assigned a specific frequency band for use. Neighboring cells are set up to use bands that don’t overlap.