Kyle Broussard, Alexandra Mikolai, The TCP/IP Model Kyle Broussard, Alexandra Mikolai, and Joseph Thrower Today we are going to talk about the TCP/IP protocol suite. It is the most widely used and most widely available protocol suite. It consists of four layers, each layer depicts some functionality which can be carried out by a protocol. The four layers are the application layer, the transport layer, the internet layer and the link layer which is also sometimes called the network interface layer. Joe – 1-2 & 7-12 Alex – 3-4 Kyle – 5-6

The Client (your laptop) The interaction between two computers over the network through TCP/IP take place in the form of a client server architecture. The client requests for a service while the server processes the request for the client. For example, when you access a website from your laptop your laptop is acting as the host, or client requesting permission from the server to view the website.

Application Layer HTTP, FTP, SMTP, SNMP Creates data The application layer is the first layer of the TCP/IP architecture. The application layer has various protocols that applications use to communicate with the transport layer. In the example of connecting to a website, the application layer will use HTTP, or hypertext transfer protocol in order to communicate. The application layer is responsible for creating the data.

Breaks data into chunks Transport Layer TCP vs. UDP Breaks data into chunks The transport layer is involved with the assembly and disassembly of data. Some protocols require that the client and server verify that they have a good connection before a message is sent. These connection-oriented protocols are called Transmission Control Protocols, or TCP. An example of a TCP protocol is the POP, or post office protocol, it is the protocol used when sending and receiving emails. Another type of protocol used in the transport layer is called the User Datagram Protocol, or UDP. UDP is a connectionless protocol, it doesn’t require verification of a good connection before data is sent. An example of UDP is online video streaming. When data goes through the transport layer it is broken up into chunks. Those chunks are then put into either TCP segments or UDP datagrams depending on the protocol that is used. TCP Segment Destination port Source port Sequence number Checksum Flags Acknowledgements Data UDP Datagram Destination port Source port Sequence number Checksum Data

Packages data into IP packets Internet Layer Packages data into IP packets Routes IP packets The internet layer packages data into IP packets which contain source and destination address information that is used to forward the packets between hosts and across networks. It also performs the routing of IP packets. The internet layer isn’t concerned with the type of data in the IP packet or whether the data arrives on good order or not.

Link Layer (network interface) Cabling, hubs, physical addresses, and NICs Wraps IP packet into a frame with the MAC and a FCS. The Link Layer, also called the network interface layer, combines the data link and physical layer from the OSI model. Cabling, hubs, physical addresses, and NICs are all in the Link Layer. The link layer wraps the IP packets into a frame with the MAC address information and a frame check sequence (FCS). Any part of a network that deals with a complete frame is in the link layer.

Media for Data Transfer After the frames are assembled, they are ready to be transferred over the network.

Link Layer (network interface) The data follows the same path as before, but in reversed order. The frame goes to the link layer. At this layer the information which was stuffed by the link layer protocol of the host machine is read and rest of the data is passed to the upper layer.

Internet Layer At the internet layer, the information set by the internet layer protocol of the host machine is read and rest of the information is passed on the next upper layer.

Transport Layer Same happens at the transport layer

Application Layer and finally the HTTP request sent by the host application(your browser) is received by the target application(Website server).

The Server (webserver)