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TCP/IP Protocol Suite and Internetworking

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TCP/IP Protocol Suite and Internetworking TCP/IPTCP/IP ProtocolProtocol SuiteSuite andand InternetworkingInternetworking Raj Jain Professor of CIS The Ohio State University Columbus, OH 43210 [email protected] http://www.cse.ohio-state.edu/~jain/cis677-98 The Ohio State University Raj Jain 1 OverviewOverview T Key Philosophical Differences from OSI T Layering vs Hierarchy T Protocol architecture and interfaces T Internetworking terms and services T Internet Protocol (IP): Services, Header, Address format The Ohio State University Raj Jain 2 KeyKey DifferencesDifferences FromFrom OSIOSI T Connectionless Service: TCP/IP is pro-connectionless T Simple Management T Hierarchy vs layering T Internetworking: Not in original OSI The Ohio State University Raj Jain 3 LayeringLayering TP4 Same CONS CLNS Interfaces 802.3 802.5 LLC 1 LLC 2 Physical T Each layer has to perform a set of functions T All alternatives for a row have the same interfaces T Choice at each layer is independent of other layers. T Need one component of each layer ⇒ Null components T Nth layer control info is passed as N-1th layer data. The Ohio State University Raj Jain 4 HierarchyHierarchy T Can directly use the services of a lower entity even if it is not in an adjacent layer T 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 layers The Ohio State University Raj Jain 5 TCP/IPTCP/IP ProtocolsProtocols T Network access layer: Ethernet, Token Ring T Internet layer: IP T Host-host layer: TCP, UDP T Process/application layer: FTP, Telnet, Mail (SMTP) MIME BGP FTP HTTP SMTP TELNET SNMP TCP UDP ICMP IP The Ohio State University Fig 15.12 Raj Jain 6 InternetworkingInternetworking TermsTerms T End-system: Host T Network: Provides data transfer between end-systems T Internet: A collection of networks T Subnetwork: Each component of an internet T Intermediate System: Connects two subnetworks T Port: Application processes in the host FTP Telnet SMTP FTP Telnet SMTP Host A Host B Subnet Intermediate Subnet 1 System 2 The Ohio State University Raj Jain 7 PDU’sPDU’s inin TCP/IPTCP/IP User Data Segment TCP Header Datagram IP Header Frame Datalink Header T TCP PDU = Segment T IP PDU = Datagram T Datalink PDU = Frame The Ohio State University Raj Jain 8 OperationOperation ofof TCP/IPTCP/IP T Process address within a host = Port T Host address on a network T IP deals only with host addresses = Subnet + Host # T Application messages are broken into TCP segments T TCP P Uses segment sequence number for ordering and lost segment detection P Uses checksum for error detection P Passes the segment to IP for transmission P Delivers the data to appropriate port in the destination host The Ohio State University Raj Jain 9 TCP/IPTCP/IP ApplicationsApplications T Simple Mail Transfer Protocol (SMTP): P Mail transfer between hosts P Mailing lists, mail forwarding, return receipts P Does not specify how to create messages T File transfer protocols (FTP): P Transfers files between hosts P 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 terminals The Ohio State University Raj Jain 10 InternetInternet ProtocolProtocol (IP)(IP) T IP deals with only with host addresses T Services: P Send: User to IP P Deliver: IP to User P Error (optional): IP to User The Ohio State University Raj Jain 11 IPIP HeaderHeader 4b 4b 8b 16b Ver IHL ToS Total Length Id Flags Fragment Offset TTL Protocol Header Checksum Source Address 20B Destination Address Options + Padding 3b Fig 16.7 The Ohio State University Raj Jain 12 IPIP HeaderHeader (Cont)(Cont) T Version (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 throughput T Total length (16 bits): header+data in bytes T Identifier (16 bits): Helps uniquely identify the datagram during its life for a given source, destination address The Ohio State University Raj Jain 13 IPIP HeaderHeader (Cont)(Cont) T Flags (3 bits): P More flag - used for fragmentation P No-fragmentation P Reserved T Fragment offset (13 bits): In units of 8 bytes T Time to live (8 bits): Specified in router hops T Protocol (8 bits): Next level protocol to receive the data T Header checksum (16 bits): 1’s complement sum of all 16-bit words in the header The Ohio State University Raj Jain 14 IPIP HeaderHeader (Cont)(Cont) T Source 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 recording T Padding (variable): Makes header length a multiple of 4 T Data (variable): Data + header < 65,535 bytes The Ohio State University Raj Jain 15 IPIP AddressAddress T Class A: 0 Network Local 17 24 bits q Class B: 10 Network Local 214 16 bits q Class C: 110 Network Local 321 8 bits q Class D: 1110 Host Group (Multicast) 428 bits q Local = Subnet + Host (Variable length) Router Router The Ohio State University Subnet Raj Jain 16 AddressAddress ResolutionResolution ProtocolProtocol R E T Problem: Given an IP address find the MAC address T Solution: Address resolution protocol T 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 addresses The Ohio State University Raj Jain 17 InternetInternet ControlControl MessageMessage ProtocolProtocol (ICMP)(ICMP) T Required companion to IP. Provides feedback from the network. P Destination unreachable P Echo reply P Time exceeded P Timestamp P Parameter problem P Timestamp reply P Source quench P Information Request P Redirect P Information reply P Echo The Ohio State University Raj Jain 18 AutonomousAutonomous SystemsSystems T An internet connected by homogeneous routers under the administrative control of a single entity Subnet 1.2 Subnet 1.2 R3 R2 R6 Interior Subnet 1.2 R5 Subnet 1.2 Subnet 1.2 R7 R8 R4 R1 Subnet 1.2 Exterior Subnet 1.2 Subnet 1.2 The Ohio State University Fig 16.10 Raj Jain 19 OtherOther NetworkingNetworking ProtocolsProtocols T Interior Router Protocol (IRP): Used for passing routing information among routers internal to an autonomous system T Exterior Router Protocol (ERP): Used for passing routing information among routers between autonomous systems T Routing Information Protocol (RIP): First generation ARPAnet IRP protocol. Entire routing table sent to neighbors. ⇒ Distance vector routing. The Ohio State University Raj Jain 20 NetworkingNetworking ProtocolsProtocols (Cont)(Cont) T Open Shortest Path First (OSPF): Interior routing protocol. Provides least-cost path routes using a fully user configurable routing metric (any fn of delay, data rate, dollar cost, etc.) Link costs flooded (Link-state routing) T Exterior Gateway Protocol (EGP): Periodic hellos and responses with cost to other networks The Ohio State University Raj Jain 21 SummarySummary T TCP/IP’s hierarchy vs OSI’s layering T Processes, hosts, networks, ports, subnetwork T IP: Address, header T ARP, ICMP, EGP, OSPF The Ohio State University Raj Jain 22 HomeworkHomework T Read Sections 15.3 and 16.3 in Stallings’ book T Submit answers to Exercise 16.7, 16.8 The Ohio State University Raj Jain 23.
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