CCNA Discovery 2 - Chapter 7

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CCNA Discovery 2 - Chapter 7

  1. 1. ISP Services Working at a Small-to-Medium Business or ISP – Chapter 7Version 4.1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 1
  2. 2. Objectives Describe the network services provided by an ISP. Describe the protocols that support the network services provided by an ISP. Describe the purpose, function, and hierarchical nature of the Domain Name System (DNS). Describe and enable common services and their protocols. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 2
  3. 3. Introducing ISP ServicesCritical services for small-to-medium businesses: Email Web hosting Media streaming IP telephony File transfer © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 3
  4. 4. Introducing ISP ServicesMeeting customer requirements: Reliability Availability © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 4
  5. 5. Protocols That Support ISP Services The TCP/IP suite of protocols supports reliability © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 5
  6. 6. Protocols That Support ISP Services Transport needs determine the choice of Transport Layer Protocol © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 6
  7. 7. Protocols That Support ISP ServicesThe TCP three-way handshake: Synchronization Synchronization acknowledgement Acknowledgement © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 7
  8. 8. Protocols That Support ISP ServicesHow TCP supports reliability: Acknowledgement Retransmission Sequencing Flow control © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 8
  9. 9. Protocols That Support ISP Services UDP: not connection-oriented, simple protocol Used by online games, DHCP, DNS © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 9
  10. 10. Protocols That Support ISP Services TCP and UDP use ports to support multiple services © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 10
  11. 11. Protocols That Support ISP Services Socket: combination of Transport Layer port number and Network Layer IP address of host Socket pair: source and destination IPs and port numbers identify each conversation © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 11
  12. 12. Domain Name System (DNS) Networking naming systems translate human- readable names into machine-readable addresses srv2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 12
  13. 13. Domain Name System (DNS)Advantages of DNS: Hierarchical structure Small, manageable zones Scalable © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 13
  14. 14. Domain Name System (DNS)Components of DNS: Resource records and domain namespace Domain name system servers Resolvers © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 14
  15. 15. Domain Name System (DNS)DNS name resolution: Dynamic updates Forward lookup zones Reverse lookup zones Primary zones Secondary zones © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 15
  16. 16. Domain Name System (DNS)Implementing DNS solutions: ISP DNS servers Local DNS servers © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 16
  17. 17. Services and Protocols ISPs provide many business-oriented services Secure versions of Application Layer protocols support customer security requirements © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 17
  18. 18. Services and Protocols HTTP is a request-response protocol HTTPS adds authentication and encryption © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 18
  19. 19. Services and Protocols FTP uses a protocol interpreter (PI) and data transfer process (DTP) Two connections: one to send commands, one for actual file data transfer © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 19
  20. 20. Services and Protocols SMTP: specific message format and processes running on both client and server POP3: mail is downloaded from server to client and then deleted IMAP4: keeps messages on server © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 20
  21. 21. Summary TCP and UDP use port numbers to provide multiple services to hosts. DNS uses a hierarchical system of databases to resolve names and IP addresses of known hosts within networks and across the Internet. The most common services used on the Internet include FTP, FTPS, HTTP, HTTPS and SMTP. ISPs use high-performance servers to support these services. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 21
  22. 22. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 22

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