Network Protocol Reading Notes Overview

Network Protocol Reading Notes Overview 1. Why are TCP/IP protocols required? 1) different computer hardware runs different operating systems. 2) different LAN hardware: Ethernet, Token network, etc. 3) information exchange. The TCP/IP protocol forms a wide area network composed of a single host and a single LAN information island to achieve information exchange and resource sharing. 2. internet and Internet (case-insensitive) 1) an internet (internet) is a group of networks that are interconnected through the same protocol family, A network that connects multiple networks. 2) The Internet in the world is a network that is interconnected through the TCP/IP protocol family, that is, the internet is one of the Internet, there is also an internet that is not interconnected through the TCP/IP protocol family. Internet is also called the global Internet or Internet. 3. gateways, routers, and bridges 1) the simplest network interconnection method is to connect multiple networks using routers. 2) the role of a vro is to provide connections for different types of physical networks: Ethernet, a licensing ring network, and so on. A router is also called an IP router. It is also called a gateway in many TCP/IP protocols. A vro has two or more NICs because it connects two or more inaccessible physical networks. 3) Bridge: The bridge works at the data link layer, connects two LANs, and forwards Frames Based on the MAC address. It can be seen as a bottom-layer router. The router works at the network layer, forward data based on network addresses, such as IP addresses. The storage and forwarding functions of the bridge allow the bridge to adapt to connecting two LANs using different MAC protocols, thus forming a hybrid network environment in which different LANs are connected together. 4) Currently, the term "Gateway" is generally used to represent the gateway at the application layer: A process that connects two different protocol families (for example, a conversion application between TCP/IPH and the ibm sna protocol ). TCP/IP tends to use routers instead of bridges to connect to the network. 4. hierarchical network protocols are generally developed at different levels, and each layer is responsible for different communication protocols. For example, the TCP/IP protocol family is a combination of multiple protocols at different levels. Application layer transport layer network layer Link Layer 1) link layer, also known as data link layer and network interface layer: it consists of the NIC device driver and nic of the operating system, generally, the hardware Nic implements the Ethernet and the licensing ring network protocol, and the driver Driver Nic is equivalent to implementing the link layer protocol. 2) the network layer is also called the Internet layer and the Internet layer to process group activities (IP addresses ). TCP/IP protocol families include: IP protocol (Internet Protocol), ICMP protocol (Internet Control Packet protocol), and IGMP protocol (Internet Group Management Protocol ). The IP layer provides unreliable services, but sends the group from the source node to the target node as soon as possible, without providing reliable services. 3) the transport layer provides end-to-end communication (port) for the applications of the two hosts ). It consists of TCP (Transmission Control Protocol) and UDP (user data packet protocol. TCP provides a reliable transmission layer on the unreliable IP layer. 4) the application layer protocol is used to process details of specific application services. Almost all different TCP/IP implementations provide the following common applications (services): Telnet ftp smtp snmp is generally called an end system on our computer host ), A router is called an Intermediate system ). The application layer and transport layer use the end-to-end protocol, which mainly involves the terminal number to distinguish the process service that data belongs to. The terminal system (Computer Host) needs to use the two-layer protocol. The network layer provides hop by hop protocol, which is required BY both the end system and the intermediate system because data needs to be transmitted between networks. 5. TCP/IP1) TCP/IP is a standard and a combination of multiple protocols at different levels. This standard has multiple implementations, most of which are open-source. 2) Although it is usually called the TCP/IP protocol family, the TCP/IP and IP are only two of them. The other name of the protocol is the Internet protocol family, that is, Internet protocol Suite. vi. 1) Most network applications are designed as customers-server mode (C/S mode). There are two types of servers: duplicate (UDP server) and concurrent hairstyle (TCP server ). 2) Each Nic on the Internet must have a unique Internet address (IP address). The IP address has two representation formats: 32-bit binary (generally used by computer hosts) and the point-to-decimal (which is generally convenient for human memory). The two are one-to-one and can be converted to each other. A computer or host with multiple NICs. Each interface corresponds to one IP address. 3) Internet Network Information Center (InterNIC) only allocates Network numbers, which are assigned by the system administrator. 4) divide the IP address into five categories based on the network size. The simplest way to distinguish it is to look at its first decimal integer. 5) another type of IP address is: unicast address (for a single host) and broadcast address (for all hosts on a given network) the host name is also called a domain name. In TCP/IP, the Domain Name System (DNS) is a distributed database, it provides the ing information between the IP address and the host name. We can access and identify network interfaces on the host through IP addresses and domain names to access the host. 7) tcp udp uses a 16-bit port number to represent different application processes. Well-known port numbers (server port numbers) and temporary port numbers (client port numbers) 8) Network Application Programming interface API: socket (berkeley socket), TLI (transport layer interface) 7. encapsulate (from top to bottom) each layer should add some header or tail information to the received data. User data is transmitted to the application layer protocol. the application layer protocol and the APP header form the data format of the application layer protocol. The application layer protocol data is transmitted to the transport layer TCP, and the transport layer is added to the transport layer TCP header, form a TCP segment or TCP segment for short. The transmission layer transmits the TCP segment to the IP layer, and the IP layer adds the IP segment to form an IP datagram ). The IP layer sends the IP datagram to the link layer. The link layer adds the beginning and end of the Ethernet to form a bit stream transmitted over the Ethernet, also known as a Frame ). The length of an Ethernet data frame must be between-bytes. (The data unit transmitted between the IP address and the link layer should be a packet. A group can be either an IP datagram or a Fragment of an IP datagram )) 8. Sub-use (from bottom to top peeling) when the target host receives an Ethernet data frame, the data starts to rise from the Protocol Stack from bottom to bottom, and the packet header added to each layer of protocols is removed. 9. The official Internet standards are published in RFC (Request for Comment) documents, for example, RFC1122. The larger the number, the newer the RFC content.