QUESTION

a) A switch basically operates by forwarding frames from one part of the network to another, based on MAC address. Describe the three types of switching namely store and forward switching, fast-forward cut-through switching and fragment-free cut-through switching.

b) Switching in a network isn't free from problems. Some of the most important issues that arise within a switched network are switching loops, multiple frames transmission and MAC address instability. Fortunately, the IEEE 802.1D Spanning Tree Protocol (STP) has been developed to address these issues.

Describe with the aid of a diagram(s) and with reference to the following key words, how STP operates in order to solve the above mentioned problems.

• Root Bridge
• Hello PBDU
• Designated, Blocked and Root ports
• Downtime

c) A nice feature of a switched network is the ability to set up Virtual Local Area Networks (VLANs).

(i) Explain how frame tagging within a VLAN can be used to set up trunk ports.

(ii) Explain how inter-VLAN communication can be achieved through subinterfaces.