Im going to send you something important okay ill let

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I’m going to send you something important! Okay, I’ll let you know when I get it! Okay, I’ll let you know when I get it!
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Connectionless Communications End-to-end connection is not necessary before data is sent Every packet that is sent has the destination address in the header Sufcient to move independent packets, such as in streaming media Datagram delivery is not guaranteed and lost packets cannot be resent I’m sending something! I’m sending something! ZZZzzzzZZZZzzzzZZZ ZZZzzzzZZZZzzzzZZZ
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Connection-based Protocols The Transport Layer contains both connection-oriented and connectionless protocols Transmission Control Protocol (TCP) provides a connection-based, reliable, byte- stream service to programs User Datagram Protocol (UDP) provides a connectionless, unreliable transport service
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TCP vs. UDP TCP transport is used for logging on, fle and print sharing, replication of information between domain controllers, transfer of browse lists, and other common functions. TCP can only be used for one-to-one communications UDP is often used for one-to-many communications, using broadcast or multicast IP datagrams Protocol Type Example Transmission Control Protocol (TCP) Connection- oriented Web browser User Datagram Protocol (UDP) Connectionless Streaming media
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Ports Layer 4 protocol that a computer uses for data transmission Logical communications endpoint for specifc program on computers for delivery of data sent There are a total of 65,536 ports , numbering between 0 and 65,535 Ports are defned by the Internet Assigned Numbers Authority or IANA and divided into categories
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Ports Port numbers are divided into following ranges by the IANA
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Common Port Numbers Port # Associated Protocol Full Name 21 FTP File Transfer Protocol 22 SSH Secure Shell 23 Telnet Terminal Network 25 SMTP Simple Mail Transfer Protocol 53 DNS Domain Name System 80 HTTP Hypertext Transfer Protocol 88 Kerberos Kerberos 110 POP3 Post Ofce Protocol Version 3 119 NNTP Network News Transfer Protocol 137-139 NetBIOS NetBIOS Name, Datagram, and Session Services, respectively 143 IMAP Internet Access Message Protocol
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Main functions of transport layer Segmentation Connection management Reliable and unreliable data delivery Flow control Connection multiplexing
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Layer 5 – Session Layer Manages session establishment, maintenance and termination between network devices Example: when you log on and log of This layer controls the name and address database for the OS NetBIOS (Network Basic Input Output System) is a protocol that works at this layer
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Layer 5 – Session Layer Session layer provides mechanism for controlling the dialogue between the two end systems. It defnes how to start, control and end conversations (called sessions) between applications.
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