A layer 3 switches are used to make operations of a
switch and a router. It acts like a switch because it connects devices that are
on the same ip subnet.It also like a router since it has ip routing intelligence
built in.A layer 3 switch doesnt support Wan connectivity. Layer 3 switches are
mostly used when there is a network with lots of brodcasts that need better
performance than normal or if you have subnets connected via the router. As
seen in the diagram show that a layer 3 Switch is used to distribute the
network from its self to the other switches.

<< Figure 1 (http://planet.com.tw/en/product/images/40336/XGS3-24042-3_L.gif) 2.1) The physical layout in the diagram is an extended star topology. The advantages of an extended star topology are A) New nodes or devices can be easily added or removed without affecting the rest of the network. B) Network can be monitored better because it is more centralized. C) if a node fails it doesn't affect the rest of the network. The disadvantages of the extended Star topology are A) The central device is dependent of all the nodes therefore if the central device is down the nodes connecting to it will also be down. B) The performance of the nodes is dependent on the capacity that the central device can hold. C) Since the topology requires more equipment to be implemented more money is needed. 2.2) An Extended star topology is efficient in terms of logical topology because switch0 shown in the diagram is connected directly to pc's therefor maintenance is easier also the setup is efficient when it comes to wiring because each node will be connected to a switch or hub therefor no waste of wiring is visible it is preferable to change the hub to a switch to make the network more fast 2.3) In terms of collision domain this set up is not preferred because of the hub. If it was to be changed with a switch the setup will avoid collisions. This is because the hub sends the data received to all its ports. A mechanism needs to be applied to detect collision domains. In total there are 4 collision domains.