Review of network technology theory

What is a computer network: A computer network connects two or more computers through cables or network devices to facilitate the exchange of information and shared resources between them.

Computing network function: 1: Data communication 2: Resource sharing 3: Increase Reliability 4: Improve system processing capability

A brief history of computer network development: 1: The first phase of implementation of the Internet implementation of the basic 2: The second phase: The landmark technology is the implementation of TCP/IP 3: The third Stage: Web technology will be the traditional voice, data and television network fusion.

Protocol: syntax, semantics, synchronization

ISO International Organization for Standardization OSI Open Systems Interconnection Reference Model

ANSI United States national Standardization Agency

ITU-T International Telecommunication Union

IEEE Institute of Electrical and Electronic Engineers

IEEE802.3U Hundred Gigabit Ethernet Standard

ieee802.3z Fiber Gigabit Ethernet Standard

IEEE802.3AB Twisted pair Gigabit Ethernet Standard

IEEE802.3AE Optical fiber Gigabit Ethernet Standard

Ieee802.3an Double stranded cable Gigabit Ethernet standard

IEEE802.11A frequency 5GHZ The fastest rate of up to 54mb/s

IEEE802.11B frequency 2.4GHZ The fastest rate of up to 11mb/s

ieee802.11g frequency 2.4GHZ The fastest rate of up to 54mb/s

Star Advantage: Easy to implement, easy to network expansion, easy to troubleshoot

Disadvantage: The center node pressure is high, the network cost is higher

Layered	Function	Front three layers called upper layer data Data Segment (segment) Data Packets (Packet) Data frame (frame) Data Flow (BITS)
Application Layer	interface of network service and end user (computer)
Presentation Layer	Data representation, compression
Session Layer	Set up, manage, end a reply
Transport Layer	Protocol port number, error checking (firewall)
Network layer	Logical address addressing (router)
Data Link Layer	Establish logical connection, MAC address, error checking, etc. (switch)
Physical Layer	Establish, disconnect physical connection (NIC)