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Datornätverk A – lektion 14: Applikationslagret

Datornätverk A – lektion 14: Applikationslagret. Kap 24: Sockets Kapitel 25: DNS Kapitel 26: SMTP och FTP Kapitel 27: HTTP och WWW. PART VI. Application Layer. Position of application layer. Chapter 24. Client-Server Model: Socket Interface. Figure 24.2 Client-server relationship.

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Datornätverk A – lektion 14: Applikationslagret

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  1. Datornätverk A – lektion 14:Applikationslagret Kap 24: Sockets Kapitel 25: DNS Kapitel 26: SMTP och FTP Kapitel 27: HTTP och WWW

  2. PART VI Application Layer

  3. Position of application layer

  4. Chapter 24 Client-ServerModel:Socket Interface

  5. Figure 24.2Client-server relationship

  6. Figure 24.3Connectionless iterative server

  7. Figure 24.4Connection-oriented concurrent server

  8. Figure 24.6Socket types

  9. Figure 24.7Socket interface for connectionless iterative server

  10. Figure 24.8Socket interface for connection-oriented concurrent server

  11. Chapter 25 DNS = DomainName System

  12. Figure 25.1Domain name space

  13. Domain Name System - DNS En distribuerad databas som används till att koppla IP-nummer till textbaserade internetadresser. Ex www.gb.se <-> 195.7.73.37 • Varje sökning utgår från någon av rootservrarna som håller ordning på toppdomänerna. (.com .edu .se m fl) • All information rörande en domän ligger i den ”Name Server” som hanterar domänen. • För att lägga upp en ny domän krävs ”tillstånd” från närmast högre

  14. Figure 25.2Domain names and labels

  15. Figure 25.4Domains

  16. Figure 25.5Hierarchy of name servers

  17. Note: A primary DNS server loads all information from the disk file; the secondary server loads all information from the primary server.

  18. Figure 25.7DNS in the Internet

  19. Table 25.1 Generic domain labels

  20. Table 25.2 New generic domain labels

  21. Figure 25.9Country domains

  22. Figure 25.10Inverse domain

  23. Figure 25.11Recursive resolution

  24. Figure 25.12Iterative resolution

  25. Figure 25.13Query and response messages

  26. Figure 25.14Header format

  27. Note: DNS can use the services of UDP or TCP, using the well-known port 53.

  28. LAN Tjänster • Elektronisk Post via SMTP, POP eller IMAP • Konferenssystem via USENET News och NNTP • Fildelning via t.ex NFS • Filöverföring via t.ex FTP • Skrivardelning • World Wide Web via HTTP • Massutsändningar Mbone - Multicast Backbone

  29. Chapter 26 Internet E-mail

  30. Figure 26.10Email delivery

  31. Figure 26.11POP3

  32. Figure 26.1Format of an email

  33. Figure 26.2Email address

  34. Figure 26.3User agent

  35. Figure 26.4MIME

  36. Figure 26.5MIME header

  37. Table 26.1 Data types and subtypes in MIME

  38. Table 26.2 Content-transfer encoding

  39. Figure 26. 6Base64

  40. Table 26.3 Base64 encoding table

  41. Figure 26.7Quoted-printable

  42. Figure 26.8Email client and server

  43. 26.2 File Transfer Connections Communication File Transfer User Interface Anonymous

  44. Note: FTP uses the services of TCP. It needs two TCP connections. The well-known port 21 is used for the control connection, and the well-known port 20 is used for the data connection.

  45. Figure 26.12FTP

  46. Figure 26.13Using the control connection

  47. Figure 26.14Using the data connection

  48. Figure 26.15File transfer

  49. Example 1 • Figure 26.16 (next slide) shows an example of how a file is stored. • The control connection is created, and several control commands and responses are exchanged. • Data are transferred record by record. • A few commands and responses are exchanged to close the connection.

  50. Figure 26.16Example 1

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