Let’s assume that the network has just been powered on and there hasn’t been any flow of traffic occurred over the network yet.
a) What might be in the MAC address table of the switch?
b) If PC-1 sends a packet to PC-4, what action(s) will be performed by the switch?
a) As the network is just switched on, so is the switch. Therefore, there will be no entry in the Address table (forwarding table) of the switch.
b) Switch will perform two operations. First it will check its MAC address table which is empty, and it will populate its address table with the MAC entry of the incoming packet. Secondly, it will repeat the incoming packet on all its ports other than the source port.
Now assume that some data transfer has been occurred between the following devices:
i. PC-1 and PC-4
ii. PC-7 and PC-5
iii. PC-3 and Server
iv. PC-5 and PC-8
What might be in the forwarding table of the switch? Give your answer in the >following format:
Solution:MAC Address Port Number 0200.1111.1111 Fa0/1 0200.1111.4444 Fa0/4 0200.1111.7777 Fa0/7 0200.1111.5555 Fa0/5 0200.1111.3333 Fa0/3 0100.1111.1111 Fa0/9 0200.1111.8888 Fa0/8
Let’s assume that PC-1, PC-2, PC-3 and PC-4 belong to accounts department and PC-5, PC-6, PC-7 and PC-8 belong to admin department of an organization. Both departments have some concerns regarding security of their relevant departmental data, and they want to restrict unnecessary transfer of irrelevant traffic from each other. What approach can be implemented at the switch level to separate out network traffic of both the departments without changing the physical network configuration?
Both networks can be separated out by creating two VLANs on the switch and registering appropriate interfaces on the VLANs. This network behaves just like it would with the two physical switches. Switch does learn all the MAC addresses, but the switch does not forward broadcasts or unicasts from one VLAN to the other. It keeps a separate address table for each VLAN. This way both departments will be separated out.