Network Design Scenario

Schaumburg Elementary is a four-year-old, single-level building with 12 classrooms and a library. Each classroom currently has 24 students but could possibly seat 32 students. There are currently no portable classrooms but a student enrollment growth is just starting to hit the school.

Enough computers are available for six classrooms and the library immediately, and the intent is to outfit the remaining six classrooms next year. The plan is to make the Internet and some online services available to the students. The computers are current enough to be useful for at least two years.

The library, which is somewhat centrally located, is where the server(s) and router connecting the school to the Internet will be located. Assume that all rooms will have 24 computers and that each room will use a stackable hub solution that combines a 12-port hub and a 24-port hub for 36 total ports. Being stackable units, the network will see each stack as a single 36-port device.

When looking at the scenario for the elementary school, or any networking design scenario, it is important to first understand all of the requirements that are set by the customer. We know there are enough computers to outfit seven classrooms and the library. Based upon the information provided we know we potentially have 24 students in each classroom and perhaps the same for the library, which is approximately 168 computers. Another requirement identified by the customer is that they intend to outfit another six classrooms in the next upcoming year, which means there will be a need for another 168 computers. We also know the school does not have an infinite budget and is in the classroom environment, so the room design may change based upon teachers wants or needs. The current design for the network is using a star topology and is located in a single story building. The school has agreed to upgrade from hubs to stackable switches allowing for a total of 36 ports per classroom.

The next step to choosing to most ideal solution for a customer is to know their physical layout and requirements and start choosing the media and best devices to suite the customer’s needs. Typically when designing a network it is common practice to put together a plan that meets the current requirements, plus a 30% overhead for future growth, however in this scenario the school is going to be upgrading 6 additional classrooms within the next year and each switch in the classroom already has plenty of room for future expansion with 36 ports. Since the school does not have an unlimited budget and currently has hubs in place and the building is only 4 years old, we can assume CAT-5, CAT-5e, or CAT-6 cable was previously installed into the building, and therefore we know our data speeds will be either 10/100/1000Mbps. If a previous network was not installed, we could recommend a wireless network to allow for the change of the classroom layout and to cut the costs of cabling. Since the scenario does not specify we will assume CAT-5e or CAT-6 was installed and we will reutilize current cabling infrastructure to better suit our design needs. With knowing the star topology and a current requirement for 6 classrooms to be outfitted and the library, we can begin to form a recommendation to the school. We will recommend using seven 12-port stackable switches with two uplink ports, seven 24-port switches with two uplink ports, and one core distribution switch with at least 12-gigabit ports. The uplink ports are essential because they will provide the gigabit uplink to the core switch. The second step in the design of a network is to look at the physical connectivity and put that together with current equipment that can be found on the market.

The third step in designing a network is to look at how many IP addresses will be needed and plan to accommodate all for now and the future. Since the school advised us that it could only afford 2 public IP addresses, we know we are going to using the network address translation protocol in the router and therefore we can use a private IP address range for all the devices on the network. We know the school currently needs approximately 168 IP addresses for computers, one for the server, one for the switch, and one for the router, which brings us to a total of 171 total IP addresses. A private class “C” network would accommodate 253 hosts and the current needs of this infrastructure, however we know we are going to add another 168 computers next year, so we should use a class “B” network because it allows for a total of 1,048,576 contiguous IP addresses. The 3rd step to designing a network is to plan for ease of configuration and accommodate all hosts/devices on the customer’s network.

The 4th step to the network design proposal is to get the pricing of different types of equipment from different vendors. Listed below is a price list of the necessary equipment and cabling needed for this project with references for each device.
Device Cost Quantity Reference
Solution #1
Cisco Catalyst 3750-24PS SMI Switch $3,199.99 7
Cisco WS-CE500G-12TC Switch $1,229.99 7
Cisco WS-C3560G-24PS-E Switch $6,921.95 1
Linksys Router RVS4000 $137.95 1 [URL Removed Broken link]
Blackbox Cable 1000ft $216.99 2
Belkin CAT6 RJ-45(M) Network Connector, 100 Pack $43.99 10
Crimpers $24.10 1
Total Cost $38,967.74
Solution #2
Netgear GSM7328S Switch $1,749.99 15
Netgear RP614 Router $49.99 1
Blackbox Cable 1000ft $216.99 2
Belkin CAT6 RJ-45(M) Network Connector, 100 Pack $43.99 10
Crimpers $24.10 1
Total Cost $27,198.82
Solution #3
3Com 3CR17761-91 $2,143.79 7
3Com 3CR17660-91-US $916.15 7
3Com 3C13640-US $384.33 1
Blackbox Cable 1000ft $216.99 2
Belkin CAT6 RJ-45(M) Network Connector, 100 Pack $43.99 10
Crimpers $24.10 1
Total Cost $22,701.89

Step 5 to the network design is to put together a proposal, which explains the requirements, the equipment necessary, the advantages and disadvantages of each, and the costs involved with the project.

In conclusion, when putting together a network design proposal for a customer it is best to start with looking at the customer’s requirements, then look at the physical aspects of the network, moving to the data link (switching aspects), planning the network/IP addressing, and then put it all together into one proposal to provide to the customer for them to decide which will best suite their needs.

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