History of Internet DoD sponsored ARPANET UCLA UCSB SRI UTAH Sept. 2, 1969 Oct. 29, miles End of 1969 Packet switch technique called interface message processors (IMPs) (Built by BBN company.

Outcomes History of Internet DNS TCP/IP & OSI LAN & WAN IP address

History of Internet Timeline IAB – Internet Activity Board IRTF- Internet Research Task Force

What is the Domain Name System?  The Domain Name System (DNS) helps users to find their way around the Internet.  Every computer on the Internet has a unique address – just like a telephone number – which is a rather complicated string of numbers.  It is called its "IP address" (IP stands for "Internet Protocol").

Domain Name  But it is hard to remember everyone's IP address.  The DNS makes it easier by allowing a familiar string of letters (the "domain name") to be used instead of the arcane IP address.  So instead of typing , you can type It is a "mnemonic" device that makes addresses easier to remember.

Domain Name  Translating the name into the IP address is called "resolving the domain name.”  The goal of the DNS is for any Internet user any place in the world to reach a specific website IP address by entering its domain name.  Domain names are also used for reaching addresses and for other Internet applications.

What is TCP/IP?  TCP/IP - (Transmission Control Protocol / Internet Protocol)  The protocols, or conventions, that computers use to communicate over the Internet. 2

TCP/IP 4-Layer Model Application Layer: provides a wide range of services to network users. Transport Layer: provides an end-to-end data delivery service that application processes use to exchange messages over the internet. Internet Layer: provides routing and relaying functions for carrying packets of data from a source system to a destination system through an internet. Link Layer: The main function of the network interface layer is to handle hardware-dependent functions and to present a standardized interface to the Internet layer of TCP/IP. Application Layer: provides a wide range of services to network users. Transport Layer: provides an end-to-end data delivery service that application processes use to exchange messages over the internet. Internet Layer: provides routing and relaying functions for carrying packets of data from a source system to a destination system through an internet. Link Layer: The main function of the network interface layer is to handle hardware-dependent functions and to present a standardized interface to the Internet layer of TCP/IP.

TCP/IP 4-Layer Model (DoD) Layer 4: Application Layer Layer 3: Transport Layer Layer 2: Internet Layer Layer 1: Link Layer

TCP/IP Protocol Suite TCPUDP TracerouteFTPSMTPDNSPingNFSTelnet ARPData Link RARP ICMP IPIGMP media

OSI 7-Layer Model (ISO) Layer 7: Application-specific protocols such as FTP and SMTP (electronic mail) Layer 6: Common formats for representation of data Layer 5: Management of sessions such as login to a remote computer Layer 4: Reliable delivery of data between computers Layer 3: Address assignment and data delivery across a physical network Layer 2: Format of data in frames and delivery of frames through network interface Layer 1: Basic network hardware - such as RS-232 or Ethernet

The OSI Reference Model Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Data AH Data PH Data SH Data TH Data NH Data DH Bits DT APDU PPDU SPDU TPDU Packet Frame Bit

OSI Seven-Layer Model The Application Layer describes how real work actually gets done. Ex: this layer would implement file system operations. The Presentation Layer describes the syntax of data being transferred. Ex: this layer describes how floating point numbers can be exchanged between hosts with different math formats. The Session Layer describes the organization of data sequences larger than the packets handled by lower layers. Ex: this layer describes how request and reply packets are paired in a remote procedure call. The Transport Layer describes the quality and nature of the data delivery. Ex: this layer defines if and how retransmissions will be used to ensure data delivery. The Network Layer describes how a series of exchanges over various data links can deliver data between any two nodes in a network. Ex: this layer defines the addressing and routing structure of the Internet. The Data Link Layer describes the logical organization of data bits transmitted on a particular medium. Ex: this layer defines the framing, addressing and checksumming of Ethernet packets. The Physical Layer describes the physical properties of the various communications media, as well as the electrical properties and interpretation of the exchanged signals. Ex: this layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the termination method. The Application Layer describes how real work actually gets done. Ex: this layer would implement file system operations. The Presentation Layer describes the syntax of data being transferred. Ex: this layer describes how floating point numbers can be exchanged between hosts with different math formats. The Session Layer describes the organization of data sequences larger than the packets handled by lower layers. Ex: this layer describes how request and reply packets are paired in a remote procedure call. The Transport Layer describes the quality and nature of the data delivery. Ex: this layer defines if and how retransmissions will be used to ensure data delivery. The Network Layer describes how a series of exchanges over various data links can deliver data between any two nodes in a network. Ex: this layer defines the addressing and routing structure of the Internet. The Data Link Layer describes the logical organization of data bits transmitted on a particular medium. Ex: this layer defines the framing, addressing and checksumming of Ethernet packets. The Physical Layer describes the physical properties of the various communications media, as well as the electrical properties and interpretation of the exchanged signals. Ex: this layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the termination method.

Local Area Network (LAN) Bus Star Ring

Wide Area Network (WAN) LAN Subnet Router Host

Internet Address Class Range A B D C E to to to to to Loopback: to Private: to

Internet Address Class A 0 7 bits netidhostid 24 bits Class B 1 14 bits netidhostid 16 bits 0 Class C 1 21 bits netidhostid 8 bits 10 Class D 1 Multicast group ID 28 bits Class E 1(Reserved for future use) 28 bits InterNIC (rs.internic.net)

Resources to look-up W. Stallings, Data & Computer Communications, (6th Edition), Prentice Hall,