Network Segmentation

Background knowledge:
1. Ethernet a electronic signaling method related to the physical cabling of a network. Ethernet communication allows only one device to talk at a time. So out of 253 device only one can talk, if two try to talk it is considered a network collision. Ethernet can have multiple architectures, most common is a hybrid between hub-spoke and star.
2. Access Points(AP) is a device that allow wireless device to connect to the network.  Access Points are usually connected via ethernet to a switch.  Access Points broadcast on certain frequencies 2.4ghz range small variations allow for channels.
3. IP address is much like a phone number for any network device.


In our schools the networks are divided into class C ranges.  A class C network can support 253 network devices.  This sounds like a lot of devices, but really after you figure in everybodys laptop, desktop, smartboard computer, printer, and student workstations these devices amount up.  Now, All these devices are scattered all over a school and all are just waiting to talk, which shows the reason to have a traffic handling device with some intelligence.  A traffic handling device that connects a computer to the network is a switch, a switch has some intelligence in that it keeps a log everyone that has talked on the network and trys to keep traffic decreased by linking the talker to the listener instead of pushing it out to every device on the network aka broadcast. But what if you have more that 253 devices, what if you have 400 device.  Then you have to create another network and logically divide the school into to separate pieces.  This is why you probably should create a network just for your wireless traffic, something totally different from the network that desktop computer talk on.

If you connect to a AP with a handheld or mobile device you are competing on the same network.

Example 1:
If you have two APs each on different ends of the school.  After you have join the network you are given an IP address, while you stay in the location of the AP can get to the network of internet, but if it is a mobile device then it is likely to move. If a student goes to the other end of the school, the mobile device won't work, because it was joined to AP on the other network.  For the device to work it will have to renew the IP address that is was previously issued.  This is called "Roaming".  This is a reason to have just a network for wireless devices and have it the same throughout the school.  If all APs are on the same network, then the student will not have to renew the IP address on the mobile device. RECOMMENDED.

Example 2:
If you have a limited number of wireless mobile devices, then there is not reason that they could not be on the same network as you desktop computers.  This makes it easier to communicate with other devices since they are on the sames.  But just remember this way provides little growth. And since all devices are on the same network they are all competing to talk and share the bandwidth.
NOT RECOMMENDED

NAT/PAT
Not related to the network topology or implementation, but important none the less. Many network like Radford City operate on private numbers. The difference between private and public numbers is private numbers are non-routable, which means that can't go out onto the internet and public can.  So why not use public numbers, well public numbers require money and private are free.  Well we are using private number, but they are not routable, this is where NAT comes in. NAT (Network Address Translation)  is the process of modifying IP address information in IP packet while in transit across a traffic routing device for the purpose of mapping one IP address into another. Basically this means the translation changes the IP address from a non-routable to a number that is routable.  This way you can purchase less numbers and use what you have more efficiently.  PAT is much the same idea as NAT but it involves ports on the IP address.  With PAT it is possible to have thousands of computers using the same IP address, just each network computer is assigned a port number. 

Bandwidth Competition
I talked a little bit about this is example 2.  As stated before Ethernet is a shared medium.  Everyone has to wait until it is there turn to talk.  The time a device has to wait depends on the network bandwith, and the amount the device has to transmit.  When I mentioned the network bandwidth, I mean the amount of throughput a network has.  Throughput is a  typical method of performing a measurement is to transfer a 'large' file and measure the time taken to do so. The throughput is then calculated by dividing the file size by the time to get the throughput in megabits. The more devices that you have on network the more the throughput is shared.