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Internet Protocol Architecture. Chapter 2. The Internet. Internet evolved from ARPANET Developed in 1969 by the Advanced Research Projects Agency (ARPA) of the U.S. DOD First operational packet network
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Internet Protocol Architecture Chapter 2
The Internet • Internet evolved from ARPANET • Developed in 1969 by the Advanced Research Projects Agency (ARPA) of the U.S. DOD • First operational packet network • Packet network also applied to tactical radio & satellite netsneed for interoperability led to standardized TCP/IP protocols • Internetworking standards was proposed by Vint Cerf and Bob Kahn (TCP/IP)
Key Elements • Hosts: computers, mainframes, workstations, etc. • Ethernet Switch: Connecting hosts in a LAN (multiple segments) • Routers: Connecting LANs and WANS Cisco's Catalyst Switch Each segment can be a separate building http://www.querycat.com/question/f3d88ef267ad2505f6e7cfe3061aaca3
Key Elements • ISP (Internet service provider) • Regional ISP • Backbone ISP • CPE (customer premises equipment): modems, DSL, cable modem, satellite • NAP (network access point): One of the major elements connecting ISPs • Last mile (or local loop): physical path (infrastructure) between the host and the ISP – coax. Copper, etc. • POP (point of present): ISP site with communication equipments • NSP (network service provide): The company that provides backbone services to ISPs
Internet Architecture http://navigators.com/internet_architecture.html
Example Configuration • Assume • Company C, located in San Francisco, • Has 5 hosts • Connected to an ISP Y • David located in NY • Connected to ISP Z • Uses DSL • Company A runs the NAP in West coast • And company B runs the NAP in East Coast • Peer agreement http://www.vtc.com/products/TCP/IP-for-Windows-tutorials.htm Show: POPs CPE Regional ISP
Example Configuration • Assume • Company C, located in San Francisco, • Has 5 hosts • Connected to an ISP Y • David located in NY • Connected to ISP Z • Uses DSL • Company A runs the NAP in West coast • And company B runs the NAP in East Coast • Peer agreement Show: POPs CPE Regional ISP
Network Protocols • Protocols define format, order of messages sent and received among network entities, and actions taken on message transmission • Set of rules or conventions that allow peer layers to communicate • Key features • Syntax (format of the data) • Semantics (Control information, error handling) • Timing (sequencing and synchronization)
A human protocol and a computer network protocol: TCP connection response Get http://www.awl.com/kurose-ross Got the time? 2:00 <file> time How Does a Protocol Work? Hi TCP connection request Hi
Open Systems Interconnection - OSI • Developed by the International Organization for Standardization (ISO) • Has seven layers • Is a theoretical system delivered too late! • TCP/IP is the de facto standard Peer layers communicate with one another
TCP/IP Protocol Architecture • Developed by US Defense Advanced Research Project Agency (DARPA) • For ARPANET packet switched network • Used by the global Internet • Protocol suite comprises a large collection of standardized protocols
TCP/IP Layers • Application layer • Host-to-host, or transport layer • Internet layer • Network access layer • Physical layer
Physical Layer Protocols Responsible for transporting the information encapsulating information and getting it ready for transportation Deals with physical interfaces, electrical parameters, pin outs, number of twists per foot, cable gauge, data rate, signal integrity, etc. Examples: RS-232, V.35, RJ-48, DS3, OC-n, High Speed Serial Interface
Physical Layer Protocols - Examples RS-233 Interfacing computer to modem Supports speeds up to 9.6 Kbps 25-pin or 9-pin interface V.35 Serial interface between the terminal and the digital communication equipment (T1) Supports speeds above 19.2 Kbps RJ-48 Physical interface for T1 and E1 Defined by G.703 standards DS3 Uses coaxial cable Supports 45 Mbps OC-n Fiber optic interface n can be 1,3,12,etc. Multimode or single mode High speed Serial Interface Supports 42 Mbps Interfacing ATM switches
Data Link Layer Protocols Frame and format information according to some standards Two basic categories Connection oriented Technology Establishing pre-defined virtual path upon request Many different virtual paths can reside on a physical link (like a highway system) Example: ATM and Frame Relay Protocols Connectionless Technology Only source and destination addresses are defined No pre-defined path exists between devices The actual routing path can be different depending on the network status Example: High-level Data Link Control (HDLC)
Network Protocol Layers Transporting individual packets of information through the network end-to-end Can route packets according to actual device address or network topology (connectionless) Routing is done according to the network manager or by a dynamic routing protocol Without Network layer all routings will be point-to-point Examples: Internet Protocol (IP) used on Internet Packet-based; Connectionless IPX developed by Novel used in LAN Packet-based; Connectionless
Transport Protocol Layers • Interfacing the upper layers to lower layers • Formats applications into segments • Examples: TCP and UDP Offers end-to-end flow • TCP • Provides reliable delivery of data • Keeps track of packet order • UDP • User Datagram Protocol • Does not guarantee delivery • Offers faster data delivery
Application Layer • provide support for user applications • need a separate module for each type of application
TCP/IP Applications • Simple Mail Transfer Protocol (SMTP) • Provides basic electronic mail • Only sends (forwards) mail • Uses TCP • File Transfer Protocol (FTP) • Used to send files between systems – file transfer • Uses TCP connect to check the ID and PW • Establishes another TCP connection for data transfer • Telnet • Provides remote login • Implemented in two modules: User and Server • User Telnet: Interacts with terminal I/O module • Makes the remote terminal appear as local terminal
Addressing Requirements • Two levels of addressing required • Each host on a subnet needs a unique global network address • called IP address • each application on a (multi-tasking) host needs a unique address within the host • known as a port Subnets: attached devices Defined by the network Access Layer
Operation of TCP/IP Process at A hands the message to TCP layer: Send the message to host B port 2 TCP hands the message to IP – destination will be Host B IP hands it to network Layer -> next hop is router J Conditions The signal format For the physical path
Operation of TCP/IP Data from the applications software Header contains: Destination port, sequence number Checksum Header contains: Destination of the host address Header contains: Destination subnet address – which attached device Facility request: e.g., priority
Transmission Control Protocol (TCP) • Standard transport layer for Internet is (TCP) • Provides a reliable connection for transfer of data between applications • A TCP segment is the basic protocol unit • Logical connection between peer layers • TCP provides host-to-host connection (port-to-port) • TCP tracks segments between entities for duration of each connection • Segment flow
User Datagram Protocol(UDP) • An alternative to TCP • No guaranteed delivery • No preservation of sequence • No protection against duplication • Minimum overhead • Adds port addressing to IP • That is why we need it!
IP Protocol IPv4 Addresses are 32 bits wide Its header is 20 bytes at minimum Uses doted-decimal notation (e.g. 43.23.43.56) IPv6 Provides larger address domain; addresses are 128 bits wide Multiple separate headers are supported Handles audio and video; providing high quality paths Supports unicast, multicast, anycast
OSI - review • Open Systems Interconnection • developed by the International Organization for Standardization (ISO) • has seven layers • is a theoretical system delivered too late! • TCP/IP is the de facto standard
Standardized Protocol Architectures Providing services to N+1 Multiple services: Each service has an address: Called Service access Point Each layer must interacts with three Other layers Protocols define which services are Provided
Service Primitives and Parameters N N-1 N-1 N • Adjacent layers provide services to one another: • Primitives to specify function performed • Parameters to pass data and control info
Elastic and Inelastic Traffic • Elastic traffic • can adjust to delay & throughput changes over a wide range • eg. traditional “data” style TCP/IP traffic • Inelastic traffic • does not adapt to such changes • eg. “real-time” voice & video traffic • need minimum delay requirements
General Traffic Characteristics • Throughput • Amount of data carried over time • Delay • Time it take to deliver data between hosts • Delay Variation • Variation in the time when delivering the data • Packet Loss • Packets not made it to the destination
Media Types • Text, Audio, Graphic, and Video • Different technologies are required to support various media types • Examples of multimedia technologies • Compression: JPG for images, MPG for video • Transmission and networking technologies • Protocols: RTP (real-time transport protocol) • Quality of service (QoS) – providing different levels of services to different applications
Watch this: • http://www.vtc.com/products/TCP/IP-for-Windows-tutorials.htm • TCP/IP Applet • http://www.kom.e-technik.tu-darmstadt.de/projects/iteach/itbeankit/Applets/TCP/tcp.html • Simple TCP/IP Lab • http://www.windowsnetworking.com/articles_tutorials/tsttcpip.html?printversion