The Internet
DS 4250 - Business Data Communications Slide 1
Internet z Collection of interconnected networks with a common protocols. 4TCP/IP z The networks are linked through various high-speed backbones. z Routing method is hierarchical. z Can follow the packet movement on Gemini 4$ mu trace www.dell.com
DS 4250 - Internet Slide 2
Levels of Access to The Internet
NAP
National Backbone
Regional Network
Internet Service Provider
Consumer and Business Market
¾http://www.ispworld.com/isp/bb/n_america.htm DS 4250 - Internet Slide 3
1 Internet Structure
Local ISP Local ISP Regional ISP National ISP Regional ISP National ISP NAP
National ISP NationalNational ISP ISP Regional ISP National ISP NationalNational ISP ISP NAP
NationalNational ISP ISP NationalNational ISP ISP Regional ISP Regional ISP
Local ISP Regional ISP Regional ISP Regional ISP Regional ISP Regional ISP Regional ISP MAE Local ISP Regional ISP Regional ISP Local ISP Regional ISP Local ISP
Local ISP Local ISP Local ISP Local ISP Local ISP Local ISP Local ISP Figure 9-1 Basic Internet Architecture
DS 4250 - Internet Slide 4
Concerns in Choosing an ISP
z Examine the backbone of the provider 4Does the backbone include needed areas 4Check the speed of the network 4Examine the redundancy of the network 4What power back-ups do they have 4Connections to other providers • At least three network access points 4What is the guarantee of performance
DS 4250 - Internet Slide 5
Internet Addressing z Based on the software address for each device 4A unique number for each device z Used to designate the location of the device on the network z Basic address consists of four sets of octets 4Four number from 0 to 255 (total of 32 bits) z Based on a hierarchical routing scheme 4Comparable to the PSTN numbering system 4Each octet narrows the scope of the routing process
DS 4250 - Internet Slide 6
2 Three Classes of Networks
Octet 1Octet 1 Octet 1 Octet 1
Class A: Network Host Host Host
Class B: Network Network Host Host
Class C: Network Network Network Host
DS 4250 - Internet Slide 7
Internet Classes
Class Example Number Number of Available Hosts A 12.0.0.0 127 16 million
B 149.149.0.0 16,000 65,536
C 209.18.14.0 2 Million 256
DS 4250 - Internet Slide 8
Sub-networks z Each node on the same network share the network address part of the IP address 4The remaining octets define the node address z Node address can be divided into subnets z Subnet mask defines which part of the IP address is the subnet 4255.255.0.0 --> Subnet at 2nd octet 4255.255.255.0 --> Subnet at 3rd octet
DS 4250 - Internet Slide 9
3 Internet Address Format (B Class)
Network Subnet Host
149.149.44.55
(615) 372-6308
DS 4250 - Internet Slide 10
Domain Name Services
z Responsible for mapping between host names (URLs) and IP addresses www.tntech.edu 149.149.10.1 z The task of maintaining this is divided into domains (edu, com, gov, org, etc.) 4The top level DNS for each domain is the root name servers 4Root name server does not know about individual systems within each sub-domain, only the DNS server that is responsible for them.
DS 4250 - Internet Slide 11
DNS Hierarchy
.edu DNS .com DNS .org DNS Server Server Server
Local DNS Local DNS Local DNS tntech.edu dell.com good.org
Local DNS Local DNS Local DNS etsu.edu sun.com nice.org Local DNS Local DNS Local DNS mtsu.edu microsoft.com big.org
Example: request from ns.tntech.edu to ns.etsu.edu
DS 4250 - Internet Slide 12
4 TCP/IP Protocol z Originally a military protocol designed to be dependable and resilient z Used as the common language (protocol) for all Internet traffic z Incorporates a variety of protocols at different layers in the OSI model 4Transaction Control Protocol (TCP) 4Internet Protocol (IP)
DS 4250 - Internet Slide 13
DoD versus OSI Model
DoD Model OSI Model
Application Process/ Presentation Application Session
Host-to-Host Transport
Internet Network
Data Link Network Access Physical
DS 4250 - Internet Slide 14
Process/Application Layer z Consists of various applications and services commonly used on the Internet 4Defines Node-to-Node communications z Common protocols in this layer 4Telnet 4File Transfer Protocol (FTP) 4Simple Mail Transfer Protocol (SMTP) 4Simple Network Management Protocol (SNMP)
DS 4250 - Internet Slide 15
5 Host-to-Host Protocol z Creates reliable end-to-end communications and ensures error-free delivery of data z Provides packet sequencing and data integrity z Consists of two protocols 4Transaction Control Protocol (TCP) 4User Datagram Protocol (UDP)
DS 4250 - Internet Slide 16
Internet Protocol z Provides end-to-end routing across the network 4Also controls the communications flow between two networks z Provides a single network interface to the upper-layer protocols z Separates segments from the host-to- host layer into datagrams (packets)
DS 4250 - Internet Slide 17
Network Access z Monitors the data exchange between the host and the network 4Provides the frame and physical access to the network z Works with common data link protocols 4Ethernet, Token ring, FDDI
DS 4250 - Internet Slide 18
6 Address Resolution Protocol (ARP) z Used to locate the hardware address for a host from a known IP address. 4Works with the media access control address z Needed to produce the frame for the network access layer z First checks to ARP cache. If not listed, it sends a broadcast message. The machine with the IP address sends back its MAC address
DS 4250 - Internet Slide 19
Types of Internet Servers
z Mail Server z FTP Server z Gopher Server z Web Server
DS 4250 - Internet Slide 20
World Wide Web Server
z A web (HTTP) server is a computer, connected to the Internet, that is running software compatible with the HTTP protocol. z Provides various features: 4Access control 4Encryption 4Execution of CGI files 4Configuration of the server
DS 4250 - Internet Slide 21
7 HyperText Transfer Protocol z This is the protocol that defines how the WWW works z Based on the Client/Server Model. z It is a request/response protocol. 4The client makes the request. 4The server responds to the request z This provides a stateless environment
DS 4250 - Internet Slide 22
WEB PAGE PUBLISHING
WEB page is published using WEB publishing software running either on a client or a server. WEB page is formatted using HTML (Hypertext Markup Language.) SERVER Stand-alone PC runs HTML based publishing software which creates an HTML formatted WEB page. This page is then forwarded and
WWW page WWW page LAN-Attached client runs
First choice -- click here. First choice -- click here. Second choice -- click here. Second choice -- click here. Third choice -- click here. Third choice -- click here. Fourth choice -- click here. stored on a WEB Fourth choice -- click here. Fifth choice -- click here. Fifth choice -- click here. Sixth choice -- click here. Sixth choice -- click here. Server. Server-based WEB Page publishing software to create WWW page
First choice -- click here. Second choice -- click here. Third choice -- click here. Fourth choice -- click here. an HTML formatted WEB Fifth choice -- click here. Sixth choice -- click here. MODEM HTML page which is stored on the formatted WEB Server. page
WWW page
First choice -- click here. Second choice -- click here. Third choice -- click here. Fourth choice -- click here. Fifth choice -- click here. Sixth choice -- click here. HTML request formatted page TCP/IP protocol INTERNET delivery WEB Server
supporting HTTP l WEB o
(Hypertext Transport c o
SERVER t
Protocol.) o
r
p
P I
WWW page /
First choice -- click here. Second choice -- click here.
Third choice -- click here.
Fourth choice -- click here.
Fifth choice -- click here. P Sixth choice -- click here. WEB page delivered from server to
the client for display C T
Client PC with properly formatted request for WEB page installed WEB browser software DS 4250 - Internet Slide 23
Mail Server
z Works on the store and forward principle: 4Message is sent to the server and stored for the user. 4The messages are forwarded to the user when requested. z Need client software to access the messages. z [email protected] 4carmstrong --> user name 4tntech.edu --> server name
DS 4250 - Internet Slide 24
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