Communications and Networking: An Introduction (Undergraduate Topics in Computer Science)
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The second edition of this book adds new and revised material to the step-by-step organization, chapter summaries and review questions that distinguish the original. Covers IPv6, wireless network management, mobile, grid and cloud computing and more.
sequence (because block N + 1 has not arrived intact), the receiver accepts them. When the sender has retransmitted block N + 1, it sends blocks N + 4 and N + 5 and so on. Fig. 2.17Selective retransmission The disadvantage of the go-back-N method is that some blocks will be retransmitted unnecessarily. This is a waste of bandwidth. The disadvantage of selective retransmission is that the receiver needs plenty of buffer (temporary storage) capacity in order to store temporarily data
The EIA and TIA websites can be found at http://www.tiaonline.org and http://www.eia.org. The European Telecommunications Standards Institute (ETSI) is an independent, non-profit organisation which produces telecommunications standards (http://www.etsi.org). The World Wide Web Consortium (W3C) develops specifications and software for the World Wide Web (http://www.w3.org). HTML (see Sect. 7.3.1) and Extensible Markup Language (XML) are specified by W3C. 3.7 Summary This chapter has looked at
File Transfer and the File Transfer Protocol 120 7.5.1 Anonymous FTP 121 7.5.2 TCP Control and Data Connections 122 7.5.3 FTP Transfer Modes 123 7.6 Electronic Mail 123 7.6.1 Transmitting a Message to an E-mail Server 125 7.6.2 E-mail Standards 126 7.6.3 Fetching the E-mail from the Server 128 7.7 Delivery of Streamed Content over the Internet 130 7.7.1 Streaming Audio 130 7.7.2 Voice over IP 131 7.8 P2P File Sharing 132 7.9 Instant Messaging 132 7.10 Microblogging 133 7.11 Summary
as the application to which access is being allowed. Before a user is allowed to access an application, there are exchanges between the client computer and the security server computer and between the client and the application server. The client is given an encrypted ticket. This authenticates the client as an authorised user and it is able to get access to authorised applications using the ticket. A very important point about Kerberos is that no passwords are sent over the network. This makes
host to another. traffic class field A field in the IPv6 base header that is used to specify priority. trailer See frame trailer. transceiver Transmitter/receiver device, either optical or electrical. transmission control protocol One of the most important protocols in TCP/IP networks; allows two hosts to establish a connection and exchange data. transmission medium The medium along which data is transmitted (often, but not always, a cable). transponder A radio transceiver that