design issues of data link layer ppt

... Overview Upon completion of this chapter, you will be able to: • Explain the role of Data Link layer protocols in data transmission • Describe how the Data Link layer prepares data for transmission ... support a wide variety of network functions, the Data Link layer is often divided into two sublayers: an upper sublayer and an lower sublayer – The upper sublayer defines the software processes that ... www.bkacad.com Connecting Upper Layer Services to the Media • • The Data Link layer exists as a connecting layer between the software processes of the layers above it and the Physical layer below it As such,...

Ngày tải lên: 22/12/2013, 13:17

... convlv, a set of Savitzky-Golay filter coefficients nl is the number of leftward (past) data points used, while nr is the number of rightward (future) data points, making the total number of data points ... Figure 14.8.1 Top: Synthetic noisy data consisting of a sequence of progressively narrower bumps, and additive Gaussian white noise Center: Result of smoothing the data by a simple moving window ... Luckily, since the process of least-squares fitting involves only a linear matrix inversion, the coefficients of a fitted polynomial are themselves linear in the values of the data That means that we...

Ngày tải lên: 15/12/2013, 04:15

... measure of goodness -of- fit When the third item suggests that the model is an unlikely match to the data, then items (i) and (ii) are probably worthless Unfortunately, many practitioners of parameter ... one model, the correct one, and a statistical universe of data sets that are drawn from it! Sample page from NUMERICAL RECIPES IN C: THE ART OF SCIENTIFIC COMPUTING (ISBN 0-521-43108-5) Copyright ... based on? The answer to these questions takes us into the subject of maximum likelihood estimators Given a particular data set of xi ’s and yi ’s, we have the intuitive feeling that some parameter...

Ngày tải lên: 15/12/2013, 04:15

... generalization of §15.2 is to fit a set of data points (xi , yi ) to a model that is not just a linear combination of and x (namely a + bx), but rather a linear combination of any M specified functions of ... North America) float chixy(float bang) Captive function of fitexy, returns the value of (χ2 − offs) for the slope b=tan(bang) Scaled data and offs are communicated via the global variables { int ... large that the data are consistent with a vertical (infinite b) line If siga and sigb are returned as BIG, then the data are consistent with all values of b { void avevar(float data[ ], unsigned...

Ngày tải lên: 15/12/2013, 04:15

... 690 Modeling of Data actual data set χ2 fitted parameters a0 a2 hypothetical data set a3 pe a1 hypothetical data set ex hypothetical data set true parameters a true ... value of a measured quantity, or the mean of some function of the measured quantities S The bootstrap method [1] uses the actual data set D(0), with its N data points, to S S generate any number of ... liz a tio n Chapter 15 691 synthetic data set χ2 Monte Carlo parameters (s) a1 M a3 synthetic data set χ2 a2 synthetic data set actual data set synthetic data set a4 (s) fitted parameters a0...

Ngày tải lên: 15/12/2013, 04:15

... arr=vector(1,ndatat); for (j=1;j>1,ndatat,arr); } else { j=ndatat >> 1; aa=0.5*(select(j,ndatat,arr)+select(j+1,ndatat,arr)); ... the robust choice of ρ and minimizing the expression (15.7.3) 704 Chapter 15 Modeling of Data #include #include "nrutil.h" int ndatat; float *xt,*yt,aa,abdevt; ndatat=ndata; xt=x; yt=y; ... *abdev=abdevt/ndata; } extern int ndatat; Defined in medfit extern float *xt,*yt,aa,abdevt; float rofunc(float b) Evaluates the right-hand side of equation (15.7.16) for a given value of b Communication...

Ngày tải lên: 15/12/2013, 04:15

... structural design pattern, it works very well to help organize data Often the Data Shaping Service implements the Composite design pattern Module 9: The Transactional Data Access Layer # Physical Design ... second of two modules that focus on the data access layer (DAL) In Module 8, “The Nontransactional Data Access Layer, ” you learned about data retrieval In this module, you will learn about data ... second of two modules that focus on the DAL: Module 8, “The Nontransactional Data Access Layer and Module 9, “The Transactional Data Access Layer. ” The DAL is an application’s means of access to data...

Ngày tải lên: 17/01/2014, 09:20

... Initialization Data transfer Disconnect Examples of Operation (1) Examples of Operation (2) Other DLC Protocols (LAPB,LAPD) Link Access Procedure, Balanced (LAPB) Part of X.25 (ITU-T) Subset of HDLC ... Diagram High Level Data Link Control HDLC ISO 33009, ISO 4335 HDLC Station Types Primary station Controls operation of link Frames issued are called commands Maintains separate logical link to each ... for user (next layer up) Other DLC Protocols (LLC) Logical Link Control (LLC) IEEE 802 Different frame format Link control split between medium access layer (MAC) and LLC (on top of MAC) No primary...

Ngày tải lên: 16/02/2014, 08:20

... a sofa for the living Meaning in design is closely linked to aesthetics The broader issue of what artifacts mean and how they communicate meaning is the focus of the intellectual area of design ... artifacts An example of Sottsass’s work within Memphis, another bookcase, is shown in Exhibit MEMPHIS One manifestation of cultural phenomena is the emergence of schools of design or design movements ... providing a brief review of these two perspectives, I synthesize them into the beginnings of a theory of aesthetics for design Finally, I turn to the problem of how to design beautiful artifacts...

Ngày tải lên: 19/02/2014, 17:20

... power of a memory hierarchy comes from its ability to take advantage of patterns of data use that are transient Repeated requests tend to be made to a given data item over a short period of time, ... making possible today’s spectacular pace of technology evolution in both the volume of data and the average speed of data access As we shall find in Chapter 1, however, its success is difficult to ... it based upon the explicitly hierarchical nature of most software To reflect the inferred “behind the scenes” role of hierarchically structured software, we adopt, in Chapter 1, the term hierarchical...

Ngày tải lên: 03/07/2014, 08:20

... a function of cache size Just as the miss ratio, as a function of the single-reference residency time, takes the form of a simple power law, so does the miss ratio, as a function of cache memory: ... experienced by a wide range of cached data Figures 1.4 through 1.10 present the performance of a “plain vanilla” cache, relative to average residency time, for a range of application storage pools ... pools traced during a survey oftwelve moderate to large OS/390 installations [ 17] The figures include the following OS/390 data pools: DB2: On-line DataBase (DB2) database storage Figure 1.4...

Ngày tải lên: 03/07/2014, 08:20

... oftrack interarrival times Figure 1.14 CICS storage pools: distribution ofrecord interarrival times 29 30 THE FRACTAL STRUCTURE OF DATA REFERENCE Figure 1.15 IMS storage pools: distribution of ... one level of the hierarchy, it should also apply at all of the levels below Therefore, there is no contradiction in adopting the hierarchical reuse model as a method of approximating data reference ... the 28 THE FRACTAL STRUCTURE OF DATA REFERENCE Figure 1.11 DB2 storage pools: distribution oftrack interarrival times Figure 1.12 DB2 storage pools: distribution ofrecord interarrival times Hierarchical...

Ngày tải lên: 03/07/2014, 08:20

... 42 THE FRACTAL STRUCTURE OF DATA REFERENCE A general-purpose technique exists for generating synthetic patterns of reference, which is also capable of producing references that conform ... concept of stack distance, or the depth at which previously referenced data items appear in the LRU list [8, 21] The idea is to build a history of previous references (organized in the form of an ... variety of individual “daemons”, large numbers of which can run concurrently and independently This type of benchmark structure is attractive, in that it mirrors, at a high level, the behavior of...

Ngày tải lên: 03/07/2014, 08:20

... and manage database files Databases constructed using DataBase (DB2) and Information Management System (IMS) database management software were also in heavy use Most database storage was contained ... Our examination of the installation of the case study is based on a trace of all storage subsystem I/O during 30 minutes of the morning peak The busiest 20 files (also called data sets) appearing ... FRACTAL STRUCTURE OF DATA REFERENCE Use of Memory at the I/O Interface 55 or else by subjecting it to early demotion (this can be done by placing the data at or near the bottom of the LRU list...

Ngày tải lên: 03/07/2014, 08:20

... Memory Management in an LRU Cache 63 misses, in units of seconds of delay per second of clock time, as: (5.1) Therefore, the marginal reduction of delays with added memory is: by (1.21) Thus, we ... optimal 1.1 IMPACT OF MEMORY PARTITIONING In the assumptions stated at the beginning of the section, we excluded those cases, such as a complete lack of I/O, in which any allocation of memory is as ... of some practical importance, since capacity planners must often examine 64 THE FRACTAL STRUCTURE OF DATA REFERENCE the possibility of dividing a workload among multiple storage subsystems In...

Ngày tải lên: 03/07/2014, 08:20

Ngày tải lên: 03/07/2014, 08:20

Ngày tải lên: 03/07/2014, 08:20

Ngày tải lên: 05/07/2014, 06:20

Ngày tải lên: 05/07/2014, 06:20

Ngày tải lên: 05/07/2014, 06:20