TCP/IP Protocol Suite and InternetworkingOverviewKey Differences From OSILayeringHierarchyTCP/IP ProtocolsInternetworking TermsPDU’s in TCP/IPOperation of TCP/IPTCP/IP ApplicationsInternet Protocol (IP)IP HeaderIP Header (Cont)Slide 14Slide 15IP AddressAddress Resolution ProtocolInternet Control Message Protocol (ICMP)Autonomous SystemsOther Networking ProtocolsNetworking Protocols (Cont)SummaryHomeworkRaj JainThe Ohio State University8-1TCP/IP Protocol Suite TCP/IP Protocol Suite and Internetworkingand InternetworkingRaj JainProfessor of CIS The Ohio State UniversityColumbus, OH [email protected] presentation is available on-line at:http://www.cse.ohio-state.edu/~jain/cis677-00/Raj JainThe Ohio State University8-2OverviewOverviewKey Philosophical Differences from OSILayering vs HierarchyProtocol architecture and interfacesInternetworking terms and servicesInternet Protocol (IP): Services, Header, Address formatRaj JainThe Ohio State University8-3Key Differences From OSIKey Differences From OSIConnectionless Service: TCP/IP is pro-connectionlessSimple ManagementHierarchy vs layeringInternetworking: Not in original OSIRaj JainThe Ohio State University8-4LayeringLayeringEach layer has to perform a set of functionsAll alternatives for a row have the same interfacesChoice at each layer is independent of other layers. Need one component of each layer  Null componentsNth layer control info is passed as N-1th layer data.TP4CLNS802.5PhysicalCONS802.3LLC 1 LLC 2Same InterfacesRaj JainThe Ohio State University8-5HierarchyHierarchyCan directly use the services of a lower entity even if it is not in an adjacent layerControl and data can be separate connections. Control connections may have different reliability requirements than data.Lower layer control information can be used for higher layer control, e.g., lower layer close may close all higher layersRaj JainThe Ohio State University8-6TCP/IP ProtocolsTCP/IP ProtocolsNetwork access layer: Ethernet, Token RingInternet layer: IPHost-host layer: TCP, UDPProcess/application layer: FTP, Telnet, Mail (SMTP)Fig 15.12IPTCPBGPMIMEFTP HTTP SMTP TELNET SNMPUDPICMPRaj JainThe Ohio State University8-7IntermediateSystemFTP Telnet SMTPHost AFTP Telnet SMTPHost BSubnet2Subnet1Internetworking TermsInternetworking TermsEnd-system: HostNetwork: Provides data transfer between end-systemsInternet: A collection of networksSubnetwork: Each component of an internetIntermediate System: Connects two subnetworksPort: Application processes in the hostRaj JainThe Ohio State University8-8User DataTCP HeaderIP HeaderDatalink HeaderPDU’s in TCP/IPPDU’s in TCP/IPTCP PDU = SegmentIP PDU = DatagramDatalink PDU = FrameSegmentDatagramFrameRaj JainThe Ohio State University8-9Operation of TCP/IPOperation of TCP/IPProcess address within a host = PortHost address on a networkIP deals only with host addresses = Subnet + Host #Application messages are broken into TCP segmentsTCP Uses segment sequence number for ordering and lost segment detectionUses checksum for error detectionPasses the segment to IP for transmission Delivers the data to appropriate port in the destination hostRaj JainThe Ohio State University8-10TCP/IP ApplicationsTCP/IP ApplicationsSimple Mail Transfer Protocol (SMTP):Mail transfer between hostsMailing lists, mail forwarding, return receiptsDoes not specify how to create messagesFile transfer protocols (FTP):Transfers files between hostsProvides access control (user name and password)Binary or text files are supported.Remote login (Telnet):Initially designed for simple scroll-mode terminalsRaj JainThe Ohio State University8-11Internet Protocol (IP)Internet Protocol (IP)IP deals with only with host addressesServices:Send: User to IPDeliver: IP to UserError (optional): IP to UserRaj JainThe Ohio State University8-12IP HeaderIP HeaderVer IHLToSTotal LengthId Fragment OffsetTTLProtocolHeader ChecksumSource AddressFlagsDestination Address20B4b 4b 8b 16b3bOptions + PaddingFig 16.7Raj JainThe Ohio State University8-13IP Header (Cont)IP Header (Cont)Version (4 bits)Internet header length (4 bits): in 32-bit words. Min header is 5 words or 20 bytes.Type of service (8 bits): Reliability, precedence, delay, and throughputTotal length (16 bits): header+data in bytesIdentifier (16 bits): Helps uniquely identify the datagram during its life for a given source, destination addressRaj JainThe Ohio State University8-14IP Header (Cont)IP Header (Cont)Flags (3 bits):More flag - used for fragmentationNo-fragmentationReservedFragment offset (13 bits): In units of 8 bytesTime to live (8 bits): Specified in router hopsProtocol (8 bits): Next level protocol to receive the dataHeader checksum (16 bits): 1’s complement sum of all 16-bit words in the headerRaj JainThe Ohio State University8-15IP Header (Cont)IP Header (Cont)Source Address (32 bits)Destination Address (32 bits)Options (variable): Security, source route, record route, stream id (used for voice) for reserved resources, timestamp recordingPadding (variable): Makes header length a multiple of 4Data (variable): Data + header < 65,535 bytesRaj JainThe Ohio State University8-16IP AddressIP AddressClass A: Network Local071 24 bitsNetwork Local10142 16 bitsClass B: Network Local110213 8 bitsClass C: Local = Subnet + Host (Variable length)Router RouterSubnetHost Group (Multicast)1110284 bitsClass D:Raj JainThe Ohio State University8-17R EAddress Resolution ProtocolAddress Resolution ProtocolProblem: Given an IP address find the MAC addressSolution: Address resolution protocolThe host broadcasts a request: “What is the MAC address of 127.123.115.08?”The host whose IP address is 127.123.115.08 replies back:“The MAC address for 127.123.115.08 is 8A-5F-3C-23-45-5616”A router may act as a proxy for many IP addressesRaj JainThe Ohio State University8-18Internet Control Message Internet Control Message Protocol (ICMP)Protocol (ICMP)Required companion to IP. Provides feedback from the network.Destination unreachableTime exceededParameter problemSource quenchRedirectEchoEcho reply TimestampTimestamp replyInformation RequestInformation replyRaj JainThe Ohio State University8-19Autonomous SystemsAutonomous SystemsAn internet connected