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Ch1. Protocols and Architecture

Ch1. Protocols and Architecture. 1.1 Protocols. Used for communications between entities in a system Must speak the same language Entities User applications e-mail facilities terminals Systems Computer Terminal Remote sensor. 1.2 Protocol Architecture.

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Ch1. Protocols and Architecture

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  1. Ch1. Protocols and Architecture 1.1 Protocols • Used for communications between entities in a system • Must speak the same language • Entities • User applications • e-mail facilities • terminals • Systems • Computer • Terminal • Remote sensor

  2. 1.2 Protocol Architecture

  3. 1.3 TCP/IP Protocol Suite • Dominant commercial protocol architecture • Specified and extensively used before OSI • Developed by research funded US Department of Defense • Used by the Internet An Internet According to TCP/IP TCP/IP considers all of the hosts to be connected to this larger logical network rather to their individual physical networks.

  4. TCP/IP and OSI TCP/IP and the OSI Model Encapsulation

  5. TCP/IP Protocol Architecture • Application Layer • Communication between processes or applications • End to end or transport layer (TCP/UDP/…) • End to end transfer of data • May include reliability mechanism (TCP) • Hides detail of underlying network • Internet Layer (IP) • Routing of data • Network Layer • Logical interface between end system and network • Physical Layer • Transmission medium • Signal rate and encoding

  6. 1.3.2 Network Layer IP Datagram variable-length packet (up to 65,536 bytes) two parts: header(20-60 bytes) and data

  7. 1.3.3 Addressing Physical address: local jurisdiction, easy to change. Internet address: universe jurisdiction, cannot change. Internet Address

  8. IP Addresses in Decimal Notation Class Ranges of Internet Addresses

  9. Nodes with more than one address

  10. 1.3.4 Subneting Two Levels of Hierarchy Three Levels of Hierarchy

  11. Addresses with and without Subnetting Masking

  12. Example. Find the class, netid and hostid for each address: • Class Netid Hostid • 4.23.145.90 A 4 23.145.90 • 227.34.78.7 D N/A N/A • 246.7.3.8 E N/A N/A • 129.6.8.4 B 129.6 8.4 • 198.76.9.23 C 198.76.9 23 Boundary-Level Masking Nonboundary-Level Masking IP Addr: 45. 23. 21. 8 213. 23. 47. 37 Mask 255.255. 0. 0 255.255.255.240 Subnet addr: 45. 23. 0. 0 213. 23. 47. 32 Bit-wise AND

  13. 1.3.5 Other Protocols in Network Layer ARP: find physical address from IP address RARP: find IP address from physical address. ICMP: send notification back to the sender IGMP: identify the hosts that are members of a group. Unicasting Multicasting Broadcasting One-to-one one-to-many one-to-all

  14. 1.3.6 Transport Layer TCP and UDP(User Datagram Protocol) IP: host-to-host, deliver a packet from one physical device to another TCP: port-to-port, (Buffer used by a particular process) IP addr: 32 bits-- in IP datagram Port addr: 16 bits—in TCP datagram Port Addresses

  15. UDP UDP Datagram Format UDP only provides basic functions:port addr, checksum, length. It does not provide any sequencing or reordering functions, can not specify the damaged packet

  16. TCP Segment Format TCP is a reliable stream transport port-to-port protocol. TCP generates a virtual circuit between sender and receiver that is active for the duration of a transmission. connection establishment and connection terminationalert. Sequence number. position of the data in the original data stream. Header length (HLEN): 4 bits, TCP head length:20—60 bytes Control(6 bits) :independently. Window size: size of the sliding window used in ARQ.

  17. 1.4 Application Layer 1.4.1. Client-Server Model: (many-to-one) Client:a program running on the local machine requesting service from a server. A client program is finite. Server: a program running on the remote machine provides services to the clients. A server program is infinite.

  18. 1.4.2 BOOTP and DHCP Attach to a TCP/IP internet, must know: Its IP address, its subnet mask, the IP address of a router and the IP address of a name server which stored in a configuration file. BOOTP: provide information for a diskless or first time boot computer. DHCP: provide dynamic configuration. Moving, temporary IP addr. 1.4.3 Domain name system(DNS) – map name and address Generic Domains: first level 7 possible 3-character labels: com, edu, gov, int, mil, net, org. a few more labels have been proposed: arts, firm, info, nom(personal nomenclatures), rec(recreation), store, web. Country Domains: 2-character country abbreviations. Inverse Domain: used to map a address to a name.

  19. 1.4.4 TELNET Remote Login Network Virtual Terminal(NVT):universal interface between different OSs.

  20. 1.4.5 File Transfer Protocol (FTP) Two connections (Date, Control). Which use different strategies and different port numbers. 1.4.6 Trivial File Transfer Protocol (TFTP) – copy files 1.4.7 Simple Mail Transfer Protocol (SMTP) • User Agent (UA) • Mail Transfer Agent (MTA) • Relaying • Mail gateway

  21. Figure 25-16 The Entire E-mail System

  22. Multipurpose Internet Mail Extensions(MIME) SMTP: ASCII format MIME: extend SMTP to non-ASCII Post Office Protocol (POP) – download mail from server

  23. 1.4.8 Hypertext Transfer Protocol (HTTP) -- www HTTP Transaction Uniform Resource Locator (URL): method, host, port, path

  24. Some Protocols in TCP/IP Suite PDUs in TCP/IP

  25. Exercise: A site with a given network address and mask. The administration has divided the site into several subnetworks. Choose appropriate subneaddresses, host addresses, and router addresses (b) (a)

  26. Solutions (b) (a)

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