2.1 2.1.1 1

21 2345

2.1.211 2

3 modem repeater hub switch bridge router gateway

2.1.1 d

abecb

4Firewall 5

2

2.1.311Local Area NetworkLAN 2Metropolitan Area NetworkMAN 3 Wide Area NetworkWAN

21 EthernetToken RingATM2 3 4 NovellNetware3COM3+OPENMicrosoftWindowsIBMLAN ManagerBANYANVINES

3

abdce

2.1.4 1 Protocol2Open System Interconnection OSI ISOISOIEC 7498X2007OSI OSIOSI

3 123

4OSI OSI7

2.1.3 OSI

2.1.5 1TCP/IP TCP/IP

2.1.4 TCP/IP OSITCP/IPICMP

IP

TelnetFTPTFTPSMTPDNS

TCPUDP

2TCP/IP TCP/IP1IP Internet ProtocolTCP/IP2TCP Transportation Control Protocol3UDP User Datagram Protocol4ICMP Internet Control Message Protocol5TCPUDP

2.2 2.2.11 Internet

2 1 2 3 4 5

2.2.2 1 33.6~ 56KB/s 2ADSL ADSLAsymmetric Digital Subscriber Line2 ~ 9MB/s640KB/s ~ 1MB/sADSL

3ISDN ISDNIntegrated services digital networkISDN128 KB/s64 KB/s 4DDN DDNDigital data networkDDN64 KB/s ~ 2 MB/s

5 10 ~ 100 MB/s 6 36MB/s10MB/s

7 50 ~ 100100MB/s ~ 10GB/s 8 9.6 KB/sGSM~163KB/sCDMA

2.2.3 IP IP1IP 32IP2Domain Name IPIP

Web www.cnnic.net.cn 2.2.1

.uk.au.us.ca.ch.in.cn.hk.fr.de.sg.jp.it.tw.ru.mx.mo.ws.tv.ccCocos.bz

.com .biz .edu .int .gov .org .mil .info .net .name .coop .aero .pro .museum

.ac .gov .edu .org .com .net NICNOC

.bj .ah .sc .sh .fj .gz .tj .jx .yn .cq .sd .xz .he .ha .sn .sx .hb .gs .nm .hn .qh .ln .gd .hk .jl .gx .mo .hl .hi .tw .js .xj .zj .nx

2.2.41HTTP HTTPHypertext Transfer Protocol2SMTPPOPIMAP SMTPSimple Mail Transfer ProtocolPOPPost Office Protocol IMAPPOPPOPIMAPIMAPPOP3FTP File Transfer ProtocolTCP/IPTCP/IP/

2.2.51 Hypertext Markup LanguageHTML Standard Generalized Markup LanguageSGML SGMLDTDDTD SGML HTML HTML

WebHTML 1 URL404 URL 2 3 4 5

2 Extensible Markup LanguageXMLCascading Style SheetsCSSDHTML XMLSGMLSGMLHTMLWebXMLSGMLXMLHTML XMLXSLExtensible Style LanguageXLLExtensible Linking LanguageXSLXMLHTML

2.3 2.3.1 FTP 1FTP FTP/

2FTP

FTP12FTPFTP 3FTPFTPreadme

2.3.2 Telnet Telnet 1Telnet 2Telnet loginUsernamePassword logout

2.3.3 Electronic MailE-mail 1 SMTPSimple Mail Transfer ProtocolPOPPost Office Protocol

2 @.xyz@mail.nju.edu.cn3

2.3.4WWW WWWWorld Wide WebHTTPHTML Uniform Resource LocatorURL Protocol//IP// HTTPFTPTelnetNewsFile http://www.nju.edu.cn /njuc/dep/index.htm ftp://ftp.isi.edu/

2.3.5 BBS BBSBulletin Board System BBSBBSWindows

2.3.6 GopherHttp Gopher Googlewww.google.comwww.yahoo.comwww.sohu.comwww.163.comwww.sina.com.cn+

2.42.4.1 1 Intranet

2123456

3 4WWW3 Database Server WWW

2.4.21 Extranet = +

2 1 2 3 4

31 2 3VPN IP

2.5 Electronic Data Interchange EDI

2.5.1 ISOEDIEDIUNCITRAL/ WG.4EDIEDI

EDI1EDI2 345

2.5.2 EDI EDI EDI 1GTDI 2ANSI/ASC/X.12 3UN/EDIFACT UN/EDIFACTEDIFACT

2.5.31EDI EDIEDIEDI1Mapper Flat File2Translator EDIEDI3

2 4EDI12PC3PC4EDI3

2.5.4 EDI

2.5.1EDI B

A

EDI

EDI