How to send data between two devices?
1. Locate the other side of Ip.
2. on the other side to send data to the specified application, in order to identify the programs, these networks to the application identification number is provided, these identification numbers is called a port number, called logical port.
3. Define communication rules, these rules are called protocols, generic protocol TCP and UDP have.
OSI reference model and TCP / IP reference model
TCP / IP four-layer model description:
1. Network Interface Layer: is responsible for transmitting and receiving the data frame, the layer is responsible for a frame on the web or taken down from the Internet.
2. interconnection layers: the Internet data encapsulated into packets, and performs the necessary routing algorithm.
Four interconnect protocol:
2.1 Internet Protocol IP: network between the host and is responsible for addressing and routing data packets.
2.2 ARP ARP: get the hardware address of the host the same physical network.
2.3 International Control Message Protocol ICMP: Send Subtotal error messages and reports related.
2.4 Internet Group Management Protocol IGMP: components are brought to the local host IP multicast router reporting host.
3. Transport Layer: providing a communication session between the computer, the data transmission protocol and transmission mode specified (the UDP / the TCP).
4. Application layer: network access through the layer.
