Layer 3 switches
are used as switch and a router. It acts like a switch because it connects
devices that are on the same ip subnet and like a router since it has ip
routing intelligence built in.A layer 3 switch doesn’t support Wan connectivity.
Layer 3 switches are usually used when there is a network with lots of
brodcasts that need better performance than normal or else 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.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.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 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.Leptop0 –
Uses All the 7 Layers of the OSI ModelSwitch0 –
Uses Layer 2 of the OSI ModelRouter0 –
Uses layer 3 of the OSI ModelSwitch1 –
Uses Layer 2 of the OSI ModelLaptop1 –
Uses All the 7 Layers of the OSI Model

3.2) The
transport layer which is layer 4 handles end to end processes. The network
layer which is Layer 3 is the layer that handles Per-Hop processes. The devices
that handles per-hop in this case is Router0 and the device that handles end to
end processes are the Switches 0 & 1.A Wireless Access Point is introduced to the plan so that all
the departments will have connectivity to WIFI. The device used is Cisco Wireless Access Point 551. It is made
for medium sized offices for WIFI (IEE802.11) and Lan also It features dual radio
support. Supports speed as high as 450Mbps, also its antenna is smart so wireless
coverage is automatically optimized. One also has the option to use power over ethernet
to connect it without the need for any plugs near. Bridge mode is supported for
one to expand the network.

The role of the router in joining the IEE802.3 and IEE802.11 is
called bridging. Since there is Lan and WIFI an intermediate device is needed to
help the two forms of network communicate with each other. An access point is used
as a kind of translator for the WLan and the Lan .This is done because the network
creates a ‘transparent bridge’ where the hosts will be able to communicate because
of it and it is transparent because the hosts involved doesn’t know its there to
translate from one form to another. Protocols are used to assure the bridged network
doesn’t have any loops.