高级网络技术-Upper Layers(思科教材)

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TCP – Making Conversations Reliable
TCP segment
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TCP Server Process
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TCP Connection Establishment and Termination
Establishment of TCP sessions
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TCP Connection Establishment and Termination
E-mail Services and SMTP/POP Protocols
SMTP is used to forward e-mail.
POP is used to deliver e-mail.
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FTP
FTP was developed to allow for file transfers between a client and a server.
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File Sharing Services and SMB Protocol
A file may be copied from PC to PC with Windows Explorer using the SMB protocol.
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TCP and UDP
TCP
Connection-oriented(面向连接) Reliable delivery(可靠传输) Flow control(流控) Applications that use TCP:
Web Browsers; E-mail File Transfers
UDP
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WWW Service and HTTP
In response to the request, the HTTP server returns code for a web page.
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Upper Layers
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Objectives
Roles of the Transport Layer The TCP Protocol – Communicating with Reliability Most used Application Layer Protocols A Real Case
Simple Connectionless(无连接) Low overhead(低开销) Best effort(尽力而为) Applications that use UDP:
Domain Name System (DNS); Video Streaming; Voice over IP (VoIP)
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Port Addressing
Used for Identifying the Conversations
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Port Addressing
Types of port numbers
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Most Widely-known TCP/IP Application Layer Protocols
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The Client-Sever Model
In the client/server model, the device requesting the information is called a client and the device responding to the request is called a server.
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Roles of the Transport Layer
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Two Different Transport Services
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TCP/IP application layer protocols fit roughly into the framework of the top three layers of the OSI model: Application, Presentation and Session layers.
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Port Addressing
netstat Command
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The TCP Protocol – Communicating with Reliability
E-mail Server – MDA(Mail Delivery Agent)
The MDA process governs delivery of e-mail between servers and clients.

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Telnet Services and Protocol
Telnet provides a way to use a computer, connected via the network, to access a network device as if the keyboard and monitor were directly connected to the device.
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DHCP
The DHCP server maintains a pool of IP addresses and leases an address to any DHCP-enabled client when the client is powered on.
E-mail Server – MTA(Mail Transfer Agent) The MTA process governs e-mail handling between servers and servers.
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E-mail Services and SMTP/POP Protocols
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DHCP
The Dynamic Host Configration Protocol (DHCP动态主 机配置协议) service enables devices on a network to obtain IP addresses and other information from a DHCP server.
Termination of TCP sessions
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Application Layer Protocols and Services
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OSI and TCP/IP Model Comparison
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DNS Services and Protocol
nslookup command
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DNS Services and Protocol
The DNS server stores different types of resource records used to resolve names. These records contain the name, address, and type of record.
Clients send e-mails to a server using SMTP and receive e-mails using POP3.
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E-mail Services and SMTP/POP Protocols
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WWW Service and HTTP
Entering ‘’ in the address bar of a web browser generates the HTTP ‘GET’ Message.
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Putting it All Together
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Follow Data Through an Internetwork
A simple data transfer between two hosts across an internetwork.
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DNS Services and Protocol
Domain names were created to convert the numeric address into a simple, recognizable name.
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DNS Services and Protocol
A hierarchy of DNS servers contains the resource records that match names with addresses.
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Follow Data Through an Internetwork
A simple data transfer between two hosts across an internetwork.
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WWW Service and HTTP
The browser interprets the HTML code and displays a web page.
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E-mail Services and SMTP/POP Protocols
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File Sharing Services and SMB Protocol
SMB is a client-server, request-response protocol. Servers can make their resources available to clients on the network.