Question

Consider a wired network shown in Figure 1.

Figure 1

1. Report on which layers the devices shown in Figure 1 operate.

2. If twisted pair cable is used to connect the devices in Figure 1. Identify the cables to be used to connect PC to switch, switch to router, and router to router.

b) Differentiate between a basic service set (BSS) and an extended service set (ESS). What frequencies ranges do the IEEE 802.11 a/b/g/n/ac standards use? Why are these frequencies significant?

Answer 1

* Straight cable is used to connect PC to switch.

* Straight through cable is used to connect switch to router.

* Cross over cable is used to connect router to router.

(b)

BSS and ESS

* BSS consists of group of computers and one AP which is linked to a wired LAN. But in an ESS it consists of more than one AP.

* BSS provides short range. And ESS provides more range than BSS.

* Roaming concept is not present in BSS. But the concept of roaming is there in ESS.

* BSS is secure than ESS. ESS not highly secured.

* BSS is the smallest building block of WLAN. ESS has more users than BSS.

Frequency range IEEE 802.11 a standard use = 5 GHz

Frequency range IEEE 802.11 b standard use = 2.4 GHz

Frequency range IEEE 802.11 g standard use = 2.4 GHz

Frequency range IEEE 802.11 n standard use = 2.4 - 5 GHz

Frequency range IEEE 802.11 ac standard use = 5GHz

* These standards work on Industrial, scientific and medical radio band (ISM band) . These bands can be freely used without licence . For data transmission, channels of different frequencies are used to avoid overlapping. There will be a minimum distance between these channels to avoid interference between 802.11 transmissions.