Computer Networks: A Systems Approach (5th Edition) (The Morgan Kaufmann Series in Networking)
Bruce S. Davie, Larry L. Peterson
Format: PDF / Kindle (mobi) / ePub
This best-selling and classic book teaches you the key principles of computer networks with examples drawn from the real world of network and protocol design. Using the Internet as the primary example, the authors explain various protocols and networking technologies. Their systems-oriented approach encourages you to think about how individual network components fit into a larger, complex system of interactions. Whatever your perspective, whether it be that of an application developer, network administrator, or a designer of network equipment or protocols, you will come away with a "big picture" understanding of how modern networks and their applications are built.
*Completely updated content with expanded coverage of the topics of utmost importance to networking professionals and students, including P2P, wireless, security, and applications.
*Increased focus on application layer issues where innovative and exciting research and design is currently the center of attention.
*Free downloadable network simulation software and lab experiments manual available.
A ﬁle access program like the File Transfer Protocol (FTP) or Network File System (NFS). Although many details vary—for example, whether whole ﬁles are transferred across the network or only single blocks of the ﬁle are read/ written at a given time—the communication component of remote ﬁle access is characterized by a pair of processes, one that requests that a ﬁle be read or written and a second process that honors this request. The 19 20 CHAPTER 1 Foundation process that requests access.
Kbps of a SONET link’s capacity is set aside for a voice channel that is used for maintenance. The overhead bytes of a SONET frame are encoded using NRZ, the simple encoding described in the previous section where 1s are high and 0s are low. However, to ensure that there are plenty of transitions to allow the receiver to recover the sender’s clock, the payload bytes are scrambled. This is done by calculating the exclusive OR (XOR) of the data to be transmitted and by the use of a well-known bit.
It’s worth noting that reliability is a function that may be provided at the link level, but many modern link technologies omit this function. Furthermore, reliable delivery is frequently provided at higher levels, including both transport (as described in Section 5.2) and, sometimes, the application layer (Chapter 9). Exactly where it should be provided is a matter of some debate and depends on many factors. We describe the basics of reliable delivery here, since the principles are common across.
2.6 Ethernet and multiple access networks (802.3) To complete the story about p-persistent protocols for the case when p < 1, you might wonder how long a sender that loses the coin ﬂip (i.e., decides to defer) has to wait before it can transmit. The answer for the Aloha network, which originally developed this style of protocol, was to divide time into discrete slots, with each slot corresponding to the length of time it takes to transmit a full frame. Whenever a node has a frame to send and it.
FIGURE 2.32 Access points connected to a distribution system. point (AP-1), which forwards the frame across the distribution system to AP-3, which ﬁnally transmits the frame to E. How AP-1 knew to forward the message to AP-3 is beyond the scope of 802.11; it may have used the bridging protocol described in the next chapter (Section 3.1.4). What 802.11 does specify is how nodes select their access points and, more interestingly, how this algorithm works in light of nodes moving from one cell to.