Solutions to Exercises in Software

Integrating qr-codes in Software Solutions to Exercises

TABLE 21-13

Equipment and network installation and maintenance for ISDN involves similar concepts and problems as research and development, particularly when problems are protocol-related. For this discussion, the ISDN problem solving will be mainly focused on installation, commissioning, and maintenance of ISDN equipment and networks. Problems with ISDN equipment and networks can occur at layers 1, 2, or 3. It is useful to separate these problems into connection problems and configuration problems. As with non-ISDN circuits, there are three basic areas of testing for ISDN circuits.

the number of diodes in each mixer leg from one to two in series (as well as with other techniques), and then increasing the LO drive, with a resultant improvement in IMD suppression. The intercept point indicates the mixer s capability to suppress intermodulation distortion, typically referring to two-tone, third-order intermodulation products. A high intercept point decreases the undesirable generation of this IMD. In the world of DBMs, the intercept point and the 1-dB compression point do not directly correlate to each other; so choosing a mixer simply for its high 1-dB compression point as a guarantee of increased two-tone suppression could prove a mistake. As stated, two-tone, third-order products can be reduced by increasing the level of the mixer and correspondingly increasing its LO drive and/or by decreasing the power of the input two-tone RF signal. But since we will generally use the recommended LO drive for our chosen level of mixer, which will be selected in consideration of the maximum LO power available within our design, as well as cost constraints, then decreasing the input RF level is nor-

With a /27 mask, you have actually created eight subnets; however, you need only seven for the remote offices. This leaves you one remaining subnet, but you still need to address the seven point-to-point links between the central and remote routers. Assign the first seven subnets for the remote LAN segments and use the last subnet (192.168.2.224/27) for VLSM and the point-to-point links. To accommodate the point-to-point links, use a 255.255.255.252 (/30) subnet mask, which results in the following subnetted subnets: 192.168.2.224/30, 192.168.2.228/30, 192.168.2.232/30, 192.168.2.236/30, 192.168.2.240/30, 192.168.2.244/30, 192.168.2.248/30, and 192.168.2.252/30. With a /30 mask on the 192.168.2.224 subnet, you have created eight little subnets with two hosts each. You need only seven subnets for the point-to-point links, which leaves one small subnet remaining. Figure 8-3 shows the actual networking layout based on this example. Notice that this example used two subnet mask values, 255.255.255.224 and 255.255.255.252, with the same Class C network, 192.168.2.0/24.

The last two sections in this chapter will discuss how to configure failover on the appliances. This section discusses how to set up active/standby failover by using the serial cable on the PIXs or by using LBF. The second section discusses how to set up active/ active failover on the appliances.

Summary

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Earth station site latitude 41 38 11.0 N Earth station site longitude 70 27 42.0 W Satellite Galaxy I longitude 93.5 W Solution: Convert latitude and longitude of Earth station site to decimal degrees.

Overridden methods allow C# to support runtime polymorphism. Polymorphism is essential to object-oriented programming for one reason: It allows a general class to specify methods that will be common to all of its derivatives, while allowing derived classes to define the specific implementation of some or all of those methods. Overridden methods are another way that C# implements the one interface, multiple methods aspect of polymorphism. Part of the key to applying polymorphism successfully is understanding that the base classes and derived classes form a hierarchy that moves from lesser to greater specialization. Used correctly, the base class provides all elements that a derived class can use directly. Through virtual methods, it also defines those methods that the derived class can implement on its own. This allows the derived class flexibility, yet still enforces a consistent interface. Thus, by combining inheritance with overridden methods, a base class can define the general form of the methods that will be used by all of its derived classes.

CONSTRAINT PKOffering PRIMARY KEY (OfferNo), CONSTRAINT FKCourseNo FOREIGN KEY (CourseNo) REFERENCES Course