Lecture

Week 26 Lesson Plan Addendum



Networking Lecture

Modes of Transmission



How does data get from here to there? That is the question that this lesson is to answer.


The Nic Cards use a MAC address as their identifier on the network. Each device on the network must have a unique identifier. Each manufacturer is issued a block of numbers for their devices, NIC cards or whatever.


Describe the beginnings of the network fight about standards vs. proprietary


Explain how this economic fight led to the formation of standards and committees to create standards. The network standard developed is the OSI model. Explain the seven steps and their functions then explain how the steps do not exist in the real world but are just a model for other programs. Then explain the relationship of TCP/IP to the OSI model.




Physical – Nic cards, cables, connectors, etc

Datalink – Makes the data into datagrams adding header

Network – Addresses and routes (has CRC trailer)

Transport – breaks large packets into manageable size chunks called packets

Session – establish a link between sender and receiver – hello

Presentation – Common formats between applications

Application – which program awaits the data


A typical datagram or packet of data.




Show diagram indicating transmit side vs. receive side.




Transmitting Data Packets


The data is transported out the NIC card in serial format – one bit at a time. The wire is raised to 5 volts and that represents a one by agreement. When the wire transitions to zero volts, the state of the wire represents a 0 in binary.

The transition from 5 volts to zero volts and back again is the transference of data - one bit at a time. This signal (5 volts) placed on the wire is a digital signal and looks similar to this picture. This is called narrowband transmission.



This is opposed to the analog signal that comes from a radio or your voice or some other source such as a modem. This is called broadband transmission.



Most computer communications across the internet or intranets use multiplexing to transfer many multiple packets from different users over the same medium. This is illustrated by the following diagram.




Protocols – protocols are the format used for communication by agreement. Some popular protocols are Mail, FTP, SMNO, HTML, Telnet, and AppleTalk.


Some transfer protocols are TCP, Netware, and Netbui


Some Networking protocols are IP, IPX, and Netbui


Protocol Sniffers, analyzers, ability to steal private information


LANs


Connectivity devices



Hubs – passive and powered, switched and hybrid


Repeaters – extend cable length

Bridges Connect two LAN segments together – same IP both sides



Switches – a multiport bridge that does not forward packets with the same segments but will across segments – intelligent hubs.


Routers – Intelligent switches that examine packets and only forward to the appropriate port for distribution. Operate on Layer 3 of the OSI model.


Switches and routers create and use IP Routing tables.


Gateways – same as routers


Have students visit online videos – networking.glencoe.com











Use this drawing for PO example of sending a letter