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ISP Services

ISP Services. Working at a Small-to-Medium Business or ISP – Chapter 7. Objectives. Describe the network services provided by an ISP. Describe the protocols that support the network services provided by an ISP.

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ISP Services

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  1. ISP Services Working at a Small-to-Medium Business or ISP – Chapter 7

  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.

  3. Introducing ISP Services Critical services for small-to-medium businesses: • Email • Web hosting • Media streaming • IP telephony • File transfer

  4. Introducing ISP Services Meeting customer requirements: • Reliability • Availability

  5. Protocols That Support ISP Services • The TCP/IP suite of protocols supports reliability

  6. Protocols That Support ISP Services • Transport needs determine the choice of Transport Layer Protocol

  7. Protocols That Support ISP Services The TCP three-way handshake: • Synchronization • Synchronization acknowledgement • Acknowledgement

  8. Protocols That Support ISP Services How TCP supports reliability: • Acknowledgement • Retransmission • Sequencing • Flow control

  9. Protocols That Support ISP Services • UDP: not connection-oriented, simple protocol • Used by online games, DHCP, DNS

  10. Protocols That Support ISP Services • TCP and UDP use ports to support multiple services

  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

  12. Domain Name System (DNS) • Networking naming systems translate human-readable names into machine-readable addresses srv2

  13. Domain Name System (DNS) Advantages of DNS: • Hierarchical structure • Small, manageable zones • Scalable

  14. Domain Name System (DNS) Components of DNS: • Resource records and domain namespace • Domain name system servers • Resolvers

  15. Domain Name System (DNS) DNS name resolution: • Dynamic updates • Forward lookup zones • Reverse lookup zones • Primary zones • Secondary zones

  16. Domain Name System (DNS) Implementing DNS solutions: • ISP DNS servers • Local DNS servers

  17. Services and Protocols • ISPs provide many business-oriented services • Secure versions of Application Layer protocols support customer security requirements

  18. Services and Protocols • HTTP is a request-response protocol • HTTPS adds authentication and encryption

  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

  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

  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.

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