Protocols and the TCP/IP Suite - Lecture 12

Protocols and the TCP/IP SuiteLecture 12OverviewRequirement of ProtocolWhy Layered Approach is AdoptedKey Features of a ProtocolSimple Protocol ArchitectureAddressingTCP/IP and OSI modelGeneral Networking Terminology2The Need For Protocol ArchitectureTo transfer data several tasks must be performed:1.) the source must activate communications path or inform network of destination2.) the source must make sure that destination is prepared to receive data3.) the file transfer application on source must confirm file management program at destination is prepared to accept and store file4.) a format translation function may need to be performed if the formats on systems are different3Functions of Protocol Architecturebreaks logic into subtask modules which are implemented separatelymodules are arranged in a vertical stackeach layer in the stack performs a subset of functionsrelies on next lower layer for primitive functionschanges in one layer should not require changes in other layers4Key Features of a ProtocolA protocol is a set of rules or conventions that allow peer layers to communicate.The key features of a protocol are:Syntaxformat of data blocksSemanticscontrol information for coordination and error handlingTimingspeed matching and sequencing5A Simple Protocolagents involved:applicationscomputersnetworksexamples of applications include file transfer and electronic mailthese execute on computers that support multiple simultaneous applications6Communication Layerscommunication tasks are organized into three relatively independent layers: Network access layerconcerned with the exchange of data Transport layerprovides reliable data transferApplication layerContains logic to support applications7Network Access Layercovers the exchange of data between an end system and the network that it is attached toconcerned with issues like :destination address provisioninvoking specific services like priorityaccess to & routing data across a network for two end systems attached to the same network8Transport Layerconcerned with providing reliable delivery of datacommon layer shared by all applicationsessentially independent of the nature of the applications9Application Layercontains the logic needed to support user applicationsseparate module is needed for each type of application10Protocol Architecture and Networks11Protocols in a Simplified Architecture1213 AddressingTwo levels of addressing are needed:each computer on the network has a unique network addresseach application has an address that is unique with that computer (SAPs)14Protocol Data Unit (PDU)the combination of data and control information is a protocol data unit (PDU)typically control information is contained in a PDU headercontrol information is used by the peer transport protocol at computer Bheaders may include:source port, destination port, sequence number, and error-detection code15Network Access Protocolafter receiving segment from transport layer, the network access protocol must request transmission over the networkthe network access protocol creates a network access PDU (packet) with control informationheader includes:source computer addressdestination computer addressfacilities requests16TCP/IP Protocol ArchitectureResult of protocol research and development conducted on ARPANETReferred to as TCP/IP protocol suiteTCP/IP comprises a large collection of protocols that are Internet standards17TCP/IP Layers and Example Protocols18Physical Layercovers the physical interface between computer and networkconcerned with issues like:characteristics of transmission mediumnature of the signalsdata rates19Network Access Layercovers the exchange of data between an end system and the network that it is attached toconcerned with issues like :destination address provisioninvoking specific services like priorityaccess to & routing data across a network for two end systems attached to the same network20Internet Layerimplements procedures needed to allow data to travel across multiple interconnected networksuses the Internet Protocol (IP) to provide routing functionimplemented in end systems and routers21Host-to-Host (Transport) Layerconcerned with providing reliable delivery of datacommon layer shared by all applicationsmost commonly used protocol is the Transmission Control Protocol (TCP)22Operation of TCP/IP23TCP/IP Address RequirementsTwo levels of addressing are needed:each host on a subnetwork must have a unique global internet addresseach process with a host must have an address (known as a port) that is unique within the host24TCP/IP Addressing25Operation of TCP/IP26Transmission Control Protocol (TCP)TCP is the transport layer protocol for most applicationsTCP provides a reliable connection for transfer of data between applicationsA TCP segment is the basic protocol unitTCP tracks segments between entities for duration of each connection27TCP Header28User Datagram Protocol(UDP)alternative to TCPdoes not guarantee delivery, preservation of sequence, or protection against duplicationadds port addressing capability to IPused with Simple Network Management Protocol (SNMP) 29UDP Header30IPv6Provides enhancements over existing IPDesigned to accommodate higher speeds and the mix of graphic and video dataDriving force was the need for more addresses due to growth of the InternetIPv6 includes 128-bit source and destination address fields31IPv6 Header32TCP/IP Protocols33Standardized Protocol Architectures34Layer Specific Standards35OSI Standardizationframework for standardization was motivatorlower layers are concerned with greater levels of detailseach layer provides services to the next higher layerthree key elements:Protocol specificationService definitionAddressing36Primitive TypesREQUEST A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service INDICATION A primitive issued by a service provider either to: indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or notify the service user of a provider-initiated action RESPONSE A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user CONFIRM A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user 37Service Primitives and Parametersdefine services between adjacent layers using:primitives to specify function performedparameters to pass data and control information38Internet ApplicationsApplications that operate on top of TCP include:SMTPFTPSSHTCP39Multimedia Terminology40Multimedia Terminologyaudio generally encompasses sounds that are produced by a human, telephony and related voice communications technologyimage supports the communication of individual pictures, charts, or drawingsvideo service carries sequences of pictures in timetext is information that can be entered via a keyboard and is directly readable and printable41Multimedia Applications42Domains of Multimedia Systems and Example Applications43Elastic and Inelastic Trafficcan adjust to delay and throughput changes across an internet-traditional “data” style TCP/IP trafficdoes not easily adapt to changes in delay and throughput-“real-time” traffic such as voice and videoInelastic TrafficElastic Traffic44Multimedia Technologies4546Internetworking TermsEnd System (ES) – device used to support end-user applications or servicesIntermediate System (IS) – device used to connect two networksBridge – an IS used to connect two LANs that use similar LAN protocolsRouter - an IS used to connect two networks that may or may not be similar47Functions of a RouterProvide a link between networksProvide for the routing and delivery of data between processes on end systems attached to different networksProvide these functions in such a way as not to require modifications of the networking architecture of any of the attached subnetworks48Network Differences Routers Must AccommodateAddressing schemesDifferent schemes for assigning addressesMaximum packet sizesDifferent maximum packet sizes requires segmentationInterfacesDiffering hardware and software interfacesReliabilityNetwork may provide unreliable service49Summary50Why we need protocols for communicationBenefits of adopting layered approachFrom simple to featured protocol exampleAddressing schemesStandards Comparison (TCP/IP Vs. OSI)Functionality of and important device on the basis of studied protocol