Introduction to TCP/IP

What is TCP/IP Transmission Control Protocol/Internet Protocol TCP/IP refers to an entire suite of networking protocols, developed for use on the Internet TCP and IP are certainly two of the most important

TCP/IP Characteristics TCP/IP provides the services necessary to interconnect computers and to interconnect networks, creating the Internet Independence from underlying network topology, physical network hardware, and OS Unique IP Address Universal connectivity throughout the network Standardize high-level protocols

TCP/IP Internetworking Token Ring Router Private Nets and Internet For many businesses, today’s networks are mixture of old and new technologies. IBM networks might be operating virtually in parallel with the newer LAN interconnected networks, electronic commerce, and messaging systems. Local networks, public data networks, leased lines, and high-speed mainframe channels have all been used on an opportunistic basis with little regard for overall integration and consistency. Application migrating from central hosts to distributed servers has resulted in new networking requirements and changing traffic patterns. The approach to computer communications in most organizations is changing rapidly in response to new technologies, evolving business requirements, and the need for “instant” knowledge transfer. To meet these requirements, the internetwork, whatever form it takes, must be flexible, scalable, and adaptable to suit any organizational level (branch, region, headquarters). Internetworks tie LANs and WANs, computer systems, software, and related devices together to form the corporate communications infrastructure. An internetwork moves information anywhere within a corporation and to external suppliers and customers. By serving as the organization’s information highway, the internetworks has become a key strategic asset and a competitive advantage. FDDI

LAN and Devices LANs are designed to : Operate within a limited geographic area Allow multiaccess to high-bandwidth media Control the network privately under local administration Provide full-time connectivity to local services Connect physically adjacent devices Most of the network administrator’s tasks deal with local area networks (LANs). Major characteristics of LANs follow: The network operates within a building or floor of a building. The geographic scope for ever more powerful LAN desktop devices running more powerful applications is for less area per LAN. LANs provide multiple connected desktop devices (usually personal computers) with access to high-bandwidth media. An enterprise purchases the media and connections used in the LAN; the enterprise can privately control the LAN as it chooses. LANs rarely shut down or restrict access to connected workstations; local services are usually always available. By definitions, the LAN connects physically adjacent devices on the media. LAN devices include Bridges that connect LAN segments and help filter traffic Hubs that concentrate LAN connection and allow use of twisted pair copper media Ethernet switches that offer full-duplex, dedicated bandwidth to segments or desktops Routers that offer many services including internetworking and broadcast control ATM switches that provide high-speed cell switching Ethernet Switch ATM Switch Bridge Hub Router

Wide-Area Networks and Devices WANs are designed to : Operate over geography of telecommunications carriers Allow access over serial interfaces operating at lower speeds Control the network subject to regulated public services Provide full-time and part-time connectivity Connect devices separated over wide, even global areas Most of the network administrator’s wide-area network(WAN) tasks deal with remote access to distributed locations. Major characteristics of WANs follow: The network operatesbeyond the local LAN’s geographic scope. It uses the services of telecommunications carriers like Regional Bell Operating Companies (RBOCs). LANs provide serial connections (usually over a LAN-to-WAN device) with access to lower speed bandwidth. An enterprise pays the carrier or service provider for connections used in the WAN; the enterprise can choose which services it uses; carriers are usually regulated by tariffs. WANs rarely shutdown, but since the enterprise must pay for services used, it might restrict access to connected workstations. All WAN services are not available in all locations. By definitions, the WAN connects devices separated by wide areas. WAN devices include Routers that offer many services including internetworking and WAN interface controls X.25 or Frame Relay switches that connect to public data communications services Modems that interface voice-grade services; Channel Service Units / Data Service Units (CSU/DSU) that interface T1/E1 services; Terminal Adapters / Network Termination 1 (TA/NT1) that interface Integrated Services Digital Network (ISDN) services Communication servers that concentrate dial-in and dial-out user communications Multiplexors that share a WAN facility among several demand channels Asynchronous Transfer Mode (ATM) switches that provide high-speed cell switching S X.25 or Frame Relay Switch Modem CSU/DSU TA/NT1 Comm. Server ATM Switch Router Multiplexor stat mux

TCP/IP Networking Software TCP/IP protocol suites define a set of universal communication services Services can be implemented in a standardized manner in the networking software, normally bundled with OS Internet TCP/IP Comm. Software TCP/IP Comm. Software

TCP/IP and Internet 1957 USSR sputnik, USA established ARPA 1969 ARPA funded ARPANET 1971 Network with 15 nodes 1974 Cerf/Kahn Protocol 1973 Ethernet (Ph.D Dissertation Bob Metcalfe) 1982/83 TCP/IP as a core protocol 1983 4.2 BSD Unix with TCP/IP from UCB (univ. of California @ Berkley)

Internet growth Year #Hosts 69 4 84 1024 87 28174 90 313000 91 617000 69 4 84 1024 87 28174 90 313000 91 617000 92 1.1M 93 2.0M 94 3.8M 95 6.6M 96 12.8M 97 16M

Internet Technical Bodies ISOC - Internet Society. Professional society to promote the use of Internet for research and scholar communication and collaboration IAB - Internet Architecture Board. Technical oversight and coordination, falls under ISOC IETF - Internet Engineering Task force. Current protocols and specifications for standardization. Meets 3 times a year, organized in working groups IRTF - Internet Research Task force. Research oriented for future.

Internet Administrations DDN - the USA Defense Data Network is the government organization that has overall responsibilty for administrating the Internet DDN NIC (Network Information Center) assigns unique names and addresses collects and distributes information about TCP/IP protocols IANA Internet Assigned Numbers Authority assigns value for network parameters, name of services, identifiers NOC (Network Operations Center) manages communication links

IAB Standard Tracks RFC Internet Draft Proposed Standard Circulated technical documents call Request For Comments RFC Internet Draft Revision RFC protocol specifications should be stable technically and should have no bugs or holes. Proposed Standard at least 2 independent and interoperable implementations that test all specification funcions Draft Standard Official Standard have had significant field use and clear community interest in production use.

Protocol Status Levels All TCP/IP protocols have one of the following five status levels Required Recommended Elective Limited use Not recommended

Internet documents RFC STD (STandDard) FYI (For Your Information) number with RFC XXXX, more than 1700 now updated RFCs are published with new RFC numbers not all RFCs describe protocols. not all RFCs are used ftp://ds.internic.net STD (STandDard) official Internet standard FYI (For Your Information) RFC series that do not contain protocol specifications

Sample Documents RFC FYI 2030 I D. Mills, "Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI", 10/30/1996. (Pages=18) (Format=.txt) (Obsoletes RFC1769) 1879 I B. Manning, "Class A Subnet Experiment Results and Recommendations", 01/15/1996. (Pages=6) (Format=.txt) FYI 0023 Guide to Network Resource Tool. EARN Staff. March 1994. (Format:TXT=235112 bytes) (Also RFC1580) 0028 Netiquette Guidelines. S. Hambridge. October 1995. (Format: TXT=46185 bytes) (Also RFC1855)

TCP/IP Architectural Layers Application Network Applications End-to-end Services Transport Internet Routing Now you have reviewed the evolution leading to the modern networks. You have seen the use of a model and been introduced to the operations and functions at each layer. The remaining three chapters of this Introduction to Internetworking (I2I) module will proceed as follows: Applications and Upper Layers - Network applitions layers and how they provide application, data presentation, and session functions; also the upper layer that provides end-to end services between hosts using transport layer services. Physical and Data Link Layers - Data transmission services provided by lower layer functions, with specific variations for LAN and WAN framing and media. Network Layer and Path Determination - Routing using Layer3 services of the network layer, and other processes; thi is the primary domain of the router. Network Interface Network Transmission Physical

TCP/IP and OSI OSI TCP/IP Application Presentation Session Transport Network Data Link Physical Application Transport Internet Network Physical

TCP/IP majors protocols Application FTP TELNET SMTP TFTP NFS NTP SNMP NNTP DNS BOOTP DHCP HTTP X-windows Transport TCP UDP Internet IP Network Network Driver Software Physical

Communications Protocols A Communication protocol that provides a data transfer service can be either connection-oriented or connectionless Connection-oriented --A connection is generated before the data is exchanged (e.g. TCP) Connectionless -- Tries its best to delivery data, no need to establish connection (e.g. UDP)

Client-Server Relationships FTP Protocol FTP Server FTP Client One application component, called Server, provides well- defined services for application components running, called client Clients make a request for services by transmitting data to the server. Servers reply by sending data back to the client How the server knowns type of services ? TELNET Protocol TELNET Server TELNET Server TELNET Protocol TELNET Client TELNET Client FTP Protocol FTP Cleint FTP Server

Port Assignments Port numbers are generally allocated by Applications Transport Network access 1 2 3 4 ( ) ( ) ( ) ( ) Servers are known by ports number FTP 20, TELNET 23, SMTP 25, HTTP 80 Port numbers are generally allocated by 0 --not used 1-255 --Reserved ports for well-known services 256-1023 --Other reserved ports 1024-65535 --user-defined server ports Unix stores general used ports in /etc/services directory