- The development and growth of the Internet required specific protocols for Internet communication
- Two Protocols - Internet Protocol (IP) and Transport Control Protocol (TCP)
- Collectively known as the TCP/IP suite
- Each protocol is responsible for different aspects of communication:
- Internet communications uses Packet Switching to handle data transfers from the sending devices to the receiving devices
- Transferred data, such as a downloaded file, is not send across the network in a single message, but is broken down into ’packets’ of smaller pieces of data
- IP specifies the size of packets that the message is broken down into, and the IP Address of the receiving device
- TCP handles the transfer of data between the sending and receiving devices - the ‘end-to-end’ communication
- It establishes a connection, then makes sure the packets are sent and received correctly and in the right order
- If a packet does not arrive, TCP re-sends the packet
- Another protocol, the User Datagram Protocol (UDP) is used for broadcasting data. Unlike TCP, UDP does not guarantee the packet will safely arrive.
- Internet communications uses Packet Switching to handle data transfers from the sending devices to the receiving devices
OSI 7 Layer Model → TCP/IP Layers & Protocols
Frames are packets at the Network Interface layer, datagrams are packets at the Internet layer. The term packet is just a general term for any layer above the NIL. Segments are used when using TCP, otherwise UDP coins the term datagram. E.g. IP datagram, UDP datagram.
Link Network Layer
- The Link Network (aka network interface) layer corresponds to Physical and Data Link layer in the OSI 7 Layer Model. This layer deals with binary digits (0s and 1s) being transmitted across the network medium
- In many cases this will be twisted pair CAT5 Ethernet. However, token ring and fibre optic are other network technologies the layer interfaces with.
- The Network Interface layer controls the movement of bits across the medium, so it must use some organised method of managing the sending and receiving of data.
- In Ethernet networks, the commonest method is Carrier Sense Multiple Access / Collision Detection (CSMA / CD) Hardware and Collisions
| Destination Address | TCP/IP Layers |
|---|---|
| Protocols | Application |
| TCP/UDP | Transport |
| IP | Internet |
| MAC, Ethernet Frame | Network Link |