1. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 TCP/IP Application Layer

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Comparison between OSI and TCP/IP

3. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Client-Server Model (many-to-one) Client requests a service from a server Local machineRemote machine Client program runs when it is needed Server program runs infinitely

4. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Bootstrap Protocol (BOOTP) Dynamic Host Configuration Protocol (DHCP BOOTP – client-server protocol designed to provide 4 pieces of information for a diskless computer or a computer that is booted for the first time. A computer attached to TCP/IP must know the ff. info: –Its IP address –Its subnet mask –IP address of the router –IP address of the server DHCP – extension of BOOTP –Provides dynamic configuration

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 DNS in the Internet DNS –Domain Name System Domain name – name used instead of address 3 sections of domain name space (tree)

6. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Generic Domains Define registered hosts according to their generic behavior 1 st level label (3 character)  Organization types

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Country Domains De Anza College in Cupertino in California in the United States

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Inverse Domain Map an address to a name Server list an IP address of authorized clients. Client sends a query to DNS Server

9. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 TERminal Network (TELNET) Popular client-server application program –Enables the establishment of a connection to remote system in such a way that the local terminal appears to be a terminal at the remote system.

10. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Local Login Keystrokes are accepted by the terminal driver Pass the characters to OS OS interprets the combination of characters and invokes the application program

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Remote Login OS does not interpret the characters Transform the characters to a universal character set Network virtual terminal characters (NVT) Arrives at the TCP/IP stack Delivered to OS thru pseudoterminal driver

12. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Concept of NVT Network Virtual Terminal (NVT) - universal interface UNIX Ctrl+z – suspend Ctrl+c – abort Ctrl+d – end-of-file DOS Ctrl+z – end-of-file

13. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Client TELNET translates characters to NVT form Server TELNET translates NVT form into characters acceptable by the remote computer.

14. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 FTP - the standard mechanism provided by TCP/IP for copying a file from one host to another. 3 components of Client Control connection – remains connected Data connection – open and then closed for each file transferred

15. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Trivial File Transfer Protocol (TFTP) -less funtionalities than FTP ex. Diskless workstation or a router is booted, we need to download the bootstrap and configuration file

16. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SMTP Concept Simple Mail Transfer Protocol -supports e-mail -Sending single message to 1 or more recipients -Sending messages that include text, voice, video, graphics -Sending messages to users on networks outside the internet

17. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 UAs and MTs User Agent & Mail Transfer Agent

18. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Relay MTAs

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Mail Gateways Does not use TCP/IP

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 E-mail Address

21. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 MIME

22. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 POP3 and SMTP

23. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SNMP Concept Simple Network Management Protocol - for monitoring and maintaining an internet Manager – management stations - runs the SNMP client program Agent – managed station - routers/hosts that runs the SNMP server program

24. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 The agent keeps performance information in a database. –Ex. # of packets received and forwarded The manager can also make the router perform certain actions –Ex. Reboot the agent remotely at any time.

25. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Management with SNMP is based on 3 basic ideas: –A manager checks an agent by requesting information that reflects the behavior of the agent. –A manager forces an agent to perform a task by resetting values in the agent database. –An agent contributes to the management process by warning the manager of the unusual situation.

26. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Internet Management Components Management Information Base (MIB) Structure of Management Information (SMI) Its functions are to name objects; to define the type of data that can be stored in an object; to show how to encode data for transmission over the network A collection of all the objects that the manager can manage. Each agent has its own MIB.

27. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 Objects in MIB System, interface, address, translation Each group has defined variables and/or tables

28. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SNMP Messages

29. McGraw-Hill©The McGraw-Hill Companies, Inc., 2001 SNMP Messages GetRequest – sent from the manager (client) to the agent (server) to retrieve the value of a variable. GetResponse - sent from the agent to the manager in response to GetRequest and GetNextRequest. –It contains the value of the variable(s) requested by the manager. SetRequest - sent from the manager to the agent to set (store) a value in a variable. Trap – agent to manager – to report an event –Ex. Agent is rebooted; reports the time of rebooting.