Internet servers Figure B8 Servers on the internet ntp server FTP (file transfer protocol) server: maintains downloadable files cussion groups Chat rooms Information -and Services IRC Server
17 FTP (file transfer protocol) server: maintains downloadable files
Internet servers Figure B 8 Servers on the internet IRC (Internet Relay Chat )server Supports discussion groups and chat rooms ttp server 上P Mail Sorver cussion groups Information -and Services IRC Server
18 IRC (Internet Relay Chat ) server: supports discussion groups and chat rooms
Data Transmission in internet When you transmit data, it is broken up into small pieces called packets a packet is a parcel of data that is sent across a network Has the address of its sender Has the address of the destination Has some data When they reach the destination, they are put back together into original for The computers must follow proper communication protocols to transmit packets
When you transmit data, it is broken up into small pieces called packets A packet is a parcel of data that is sent across a network ◦ Has the address of its sender ◦ Has the address of the destination ◦ Has some data When they reach the destination, they are put back together into original form The computers must follow proper communication protocols to transmit packets 19
Communications protocols human protocols: network protocols: machines rather than >"what 's the time? humans >"I have a question all communication activity introductions in Internet governed by protocols specific msgs sent pecific actions taken protocols define format, order of when msgs received or msgs sent and received among other events network entities, and actions taken on msg transmission, receipt
20 human protocols: “what’s the time?” “I have a question” introductions … specific msgs sent … specific actions taken when msgs received, or other events network protocols: machines rather than humans all communication activity in Internet governed by protocols protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt
Communications protocols TCP/IP(Transport Control Protocol/Internet Protocol* 输控制协议/ Internet协议)- primary protocol for transmitting information over the Internet HTTP(Hypertexttransferprotocol超文本传输协议) supports the movement of information over the Web FTP( File transfer protocol,文件传输协议)-the communications protocol you use to transfer nformation from one computer to another
TCP/IP (Transport Control Protocol/Internet Protocol传 输控制协议/Internet协议) – primary protocol for transmitting information over the Internet HTTP (Hypertext transfer protocol超文本传输协议 ) – supports the movement of information over the Web FTP (File transfer protocol，文件传输协议) – the communications protocol you use to transfer information from one computer to another 21