6K190 Network Design and Performance University of Iowa Professor: Warren Boe Lecture Notes: 1/20/2009 Agenda Ethernet TCP/IP DoD Model IP Classes Classful Routing Department of Defense Model (DOD): AKA – Internet Suite of Protocols Is TCP/IP Model and suite of protocols created by Department of Defense to ensure data communication and integrity in the event of a catastrophic war. Comparison between DoD, OSI, & TCP/IP OSI DoD Hybrid TCP/IP OSI Application Process/Application Application Transport Host-to-Host Transport Network Internet Internet Data Link Network Access Data Link Presentation Session Physical Physical Process/Application Layer: Typical Protocols: Telnet – Terminal Emulation Access to remote machines and consoles Appears as though the terminal is connected directly to local device FTP – File Transfer Protocol: Transfers files Somewhat secure Allows directory/file manipulation (move, delete, creates, navigate structure) TFTP – Trivial File Transfer Protocol: Stripped down version of FTP No security Need to know exactly where files are located (no navigation) NFS – Network File System: Created by Sun Microsystems Transfer of files between disparate systems (i.e. UNIX and Novell or Microsoft) SMTP – Simple Mail Transfer Protocols: Spooled email transmission system SMTP – sending mail POP – receiving mail LPD – Line Printer Daemon: Remote printer sharing (UNIX/Mainframe) X Windows: GUI interface to remote system (UNIX Server). SNMP – Simple Network Management Protocol: Collects valuable network information (statistics, results and informational messages) Baseline monitoring Traps – Warnings DNS – Domain Name Services: Resolves DNS Names to IP address FQDN – Fully Qualified Domain Name Hierarchical structure that logically locates a system based on domain identifier. DHCP – Dynamic Host Configuration Protocol: Provides IP configuration of workstations/hosts Dynamic and automatic An extension of BOOTP BOOTP – manual and automatic Host-to-Host Layer Protocols: TCP – Transmission Control Protocol UDP – User Datagram Protocol Transmission Control Protocol: Connection Oriented and Reliable Slower, but Bulletproof Connection Oriented – Virtual Connection 3 – Way connection Handshake Sequenced – Packets are numbered Reliable – ACKs and NAKs Flow Control (Windowing) Overhead! TCP Header Fields: Source Port – port number of the application sending the data Destination Port – port number of the application receiving the data Sequence Number – allows receiving device to put the data “pieces” back in order. Acknowledgement Number – defines which packet(s) are expected next. Offset – lets the receiving device where header stops and data begins. Reserved – not used, always set to 0. Code Bits – controls various functions and is used to setup and terminate sessions. TCP Header Fields (continued): Window – identifies the amount of data the sender is willing to accept. Checksum – CRC error detection on both header AND data. Urgent Pointer – who cares! Option – options and padding (0 bits in size or 32). Data – the actual data being sent. Whew!!! User Datagram Protocol: Connectionless Oriented and Unreliable (in comparison to TCP) Fast and Unreliable Best Effort delivery Subsequence – no sequence numbers Unreliable – no ACKs and NAKs Connectionless – no virtual circuit, no handshaking No Windowing or Flow Control Low Overhead Examples: NFS SNMP Which protocol is used (TCP or UDP)? It’s up to the application developer. UDP Header Fields: Source Port – port number of the application sending the data Destination Port – port number of the application receiving the data Length of Segment – Length of UDP header and UDP data fields. Checksum –
