Raj JainThe Ohio State University1TCP/IP Protocol TCP/IP Protocol Suite and Suite and InternetworkingInternetworkingRaj JainProfessor of CIS The Ohio State UniversityColumbus, OH [email protected]://www.cse.ohio-state.edu/~jain/cis677-98Raj JainThe Ohio State University2OverviewOverviewTKey Philosophical Differences from OSIT Layering vs HierarchyT Protocol architecture and interfacesT Internetworking terms and servicesT Internet Protocol (IP): Services, Header, Address formatRaj JainThe Ohio State University3Key Differences From OSIKey Differences From OSITConnectionless Service: TCP/IP is pro-connectionlessT Simple ManagementT Hierarchy vs layeringT Internetworking: Not in original OSIRaj JainThe Ohio State University4LayeringLayeringTEach layer has to perform a set of functionsT All alternatives for a row have the same interfacesT Choice at each layer is independent of other layers. T Need one component of each layer ⇒ Null componentsT Nth layer control info is passed as N-1th layer data.TP4CLNS802.5PhysicalCONS802.3LLC 1 LLC 2Same InterfacesRaj JainThe Ohio State University5HierarchyHierarchyTCan directly use the services of a lower entity even if it is not in an adjacent layerT Control and data can be separate connections. Control connections may have different reliability requirements than data.T Lower layer control information can be used for higher layer control, e.g., lower layer close may close all higher layersRaj JainThe Ohio State University6TCP/IP ProtocolsTCP/IP ProtocolsTNetwork access layer: Ethernet, Token RingT Internet layer: IPT Host-host layer: TCP, UDPT Process/application layer: FTP, Telnet, Mail (SMTP)Fig 15.12IPTCPBGPMIMEFTP HTTP SMTP TELNET SNMPUDPICMPRaj JainThe Ohio State University7IntermediateSystemFTP Telnet SMTPHost AFTP Telnet SMTPHost BSubnet2Subnet1Internetworking TermsInternetworking TermsTEnd-system: HostT Network: Provides data transfer between end-systemsT Internet: A collection of networksT Subnetwork: Each component of an internetT Intermediate System: Connects two subnetworksT Port: Application processes in the hostRaj JainThe Ohio State University8User DataTCP HeaderIP HeaderDatalink HeaderPDU’s PDU’s in TCP/IPin TCP/IPTTCP PDU = SegmentT IP PDU = DatagramT Datalink PDU = FrameSegmentDatagramFrameRaj JainThe Ohio State University9Operation of TCP/IPOperation of TCP/IPTProcess address within a host = PortT Host address on a networkT IP deals only with host addresses = Subnet + Host #T Application messages are broken into TCP segmentsT TCP P Uses segment sequence number for ordering and lost segment detectionP Uses checksum for error detectionP Passes the segment to IP for transmission P Delivers the data to appropriate port in the destination hostRaj JainThe Ohio State University10TCP/IP ApplicationsTCP/IP ApplicationsTSimple Mail Transfer Protocol (SMTP):P Mail transfer between hostsP Mailing lists, mail forwarding, return receiptsP Does not specify how to create messagesT File transfer protocols (FTP):P Transfers files between hostsP Provides access control (user name and password)P Binary or text files are supported.T Remote login (Telnet):P Initially designed for simple scroll-mode terminalsRaj JainThe Ohio State University11Internet Protocol (IP)Internet Protocol (IP)TIP deals with only with host addressesT Services:P Send: User to IPP Deliver: IP to UserP Error (optional): IP to UserRaj JainThe Ohio State University12IP HeaderIP HeaderVer IHLToSTotal LengthId Fragment OffsetTTLProtocolHeader ChecksumSource AddressFlagsDestination Address20B4b 4b 8b 16b3bOptions + PaddingFig 16.7Raj JainThe Ohio State University13IP Header (Cont)IP Header (Cont)TVersion (4 bits)T Internet header length (4 bits): in 32-bit words. Min header is 5 words or 20 bytes.T Type of service (8 bits): Reliability, precedence, delay, and throughputT Total length (16 bits): header+data in bytesT Identifier (16 bits): Helps uniquely identify the datagram during its life for a given source, destination addressRaj JainThe Ohio State University14IP Header (Cont)IP Header (Cont)TFlags (3 bits):P More flag - used for fragmentationP No-fragmentationP ReservedT Fragment offset (13 bits): In units of 8 bytesT Time to live (8 bits): Specified in router hopsT Protocol (8 bits): Next level protocol to receive the dataT Header checksum (16 bits): 1’s complement sum of all 16-bit words in the headerRaj JainThe Ohio State University15IP Header (Cont)IP Header (Cont)TSource Address (32 bits)T Destination Address (32 bits)T Options (variable): Security, source route, record route, stream id (used for voice) for reserved resources, timestamp recordingT Padding (variable): Makes header length a multiple of 4T Data (variable): Data + header < 65,535 bytesRaj JainThe Ohio State University16IP AddressIP AddressT Class A: Network Local071 24 bitsNetwork Local10142 16 bitsq Class B: Network Local110213 8 bitsq Class C: q Local = Subnet + Host (Variable length)Router RouterSubnetHost Group (Multicast)1110284 bitsq Class D:Raj JainThe Ohio State University17R EAddress Resolution ProtocolAddress Resolution ProtocolTProblem: Given an IP address find the MAC addressT Solution: Address resolution protocolT The host broadcasts a request: “What is the MAC address of 127.123.115.08?”T 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”T A router may act as a proxy for many IP addressesRaj JainThe Ohio State University18Internet Control Message Internet Control Message Protocol (ICMP)Protocol (ICMP)TRequired companion to IP. Provides feedback from the network.P Destination unreachableP Time exceededP Parameter problemP Source quenchP RedirectP EchoP Echo reply P TimestampP Timestamp replyP Information RequestP Information replyRaj JainThe Ohio State University19Autonomous SystemsAutonomous SystemsTAn internet connected by homogeneous routers under the administrative control of a single entityFig 16.10Subnet 1.2Subnet 1.2Subnet 1.2Subnet 1.2Subnet 1.2Subnet 1.2Subnet 1.2Subnet 1.2R2R7R4R1R6R8R5R3InteriorExteriorRaj JainThe Ohio State University20Other Networking ProtocolsOther Networking ProtocolsTInterior Router Protocol (IRP): Used for passing routing information among routers internal to an autonomous systemT Exterior Router Protocol (ERP): Used for passing routing information among routers between autonomous systemsT Routing Information Protocol (RIP): First generation ARPAnet IRP protocol. Entire