Lecture-3 ISO Model, Network Security, and Protocols

It allows applications to communicate with the

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Unformatted text preview: ication layer determines whether a remote communication partner is available and accessible. It also ensures that sufficient resources ecture-3 are available to support Lthe requested 27 Application Layer …cont. Numerous application-specific protocols are found within this layer, Hypertext Transfer Protocol (HTTP) File Transfer Protocol (FTP) Line Print Daemon (LPD) Simple Mail Transfer Protocol (SMTP) Telnet Trivial File Transfer Protocol (TFTP) Electronic Data Interchange (EDI) Post Office Protocol version 3 Lecture-3 28 Application Layer …cont. There is a network device (or service) that works at the Application layer, namely the gateway. However, an Application layer gateway is a very specific type of component. Serves as a protocol translation tool. For example, an IP-to-IPX gateway takes inbound communications from TCP/IP and translates them over to IPX/SPX for outbound transmission. Lecture-3 29 TCP/IP Model The TCP/IP model (also called the DARPA or the DOD model) consists of only four layers, as opposed to the OSI Reference Model’s seven. These four layers can be compared to the seven layers of the OSI model. The four layers of the TCP/IP model are Application, Host-to-Host, Internet, and Network Access. The TCP/IP protocol suite was Lecture-3 30 developed before the OSI Reference TCP/IP Model … cont. The TCP/IP model’s Application layer corresponds to layers 5, 6, and 7 of the OSI model. The TCP/IP model’s Host-to-Host layer corresponds to layer 4 from the OSI model. The TCP/IP model’s Internet layer corresponds to layer 3 from the OSI model. The TCP/IP model’s Network Access layer corresponds to layers 1 and 2 from Lecture-3 31 the OSI model. TCP/IP Model … cont. Lecture-3 32 Communications and Network Security Network Cabling: The type of connectivity media employed in a network is important to the network’s design, layout, and capabilities. Without the right cabling, a network may not be able to span your entire enterprise or it may not support the necessary traffic volume. The most common causes of network Lecture-3 33 failure (...
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