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Consider the following scenario: What would happen if all such devices automatically communicated with each other? The demands on the network become fairly clear. For this example, consider that no fundamental changes have occurred from a business or humanistic perspective.

Let’s say I received an e-mail message informing me that a friend is flying into the local airport at noon. I received the message at 10 a.m., and I’ve just gone to a meeting.

What if the network allowed a parser (a program that scans text) in my e-mail application to identify this message as being important—beyond the scope of urgent used today. The application could connect to my PDA over a wireless link and determine that I had just entered a meeting. Rather than disturbing me, the application could also determine that I had no plans for lunch. The application could send a response to my friend noting that I was unavailable to confirm, but that I would tentatively agree to lunch. Another application could propose three restaurants in the area.

My friend would respond to the e-mail and note that the $100-hamburger place at the airport was fine (ask a pilot if you don’t get the reference). My calendar (possibly as part of my PDA) would automatically receive the update and, when my meeting was over, pop up a confirmation. An application could also automatically make a reservation at the restaurant, again over the network.

Notice how much of this exchange relied on the application layer and not the network. However, the applications required complete interconnectivity between devices—wireline and wireless—in order to complete the process.

It is likely that the majority of the hurdles in the foreseeable future will be based in Layer 8—politics. Even the end-user financial issues will pale in comparison, according to many researchers. As the model migrates toward services rather than transport, network designers will likely need to concern themselves less with the minutiae of packet flows and more with the interoperability of the services themselves. Stated another way, the challenge will be to explain and address corporate needs in nontechnical ways while also understanding the interoperability of the applications and their individual links. Billing for packets, for example, may become one of many new areas that require attention from the designer.

Few would argue that the computer revolution has just begun. There are legitimate concerns regarding the ability of the marketplace to continue support of such rapid and massive change. However, it appears probable that change will continue at a rapid pace.


This chapter dealt with some of the issues that confront network designers but that are not part of the Cisco exam objectives. In reality, this chapter could continue for quite some length, as the release of new products requires an ever-increasing dialog regarding the functionality that can be exploited from network technology.

I hope that you’ve enjoyed this text and wish you luck on both your exam and future endeavors. I sincerely believe that this text, coupled with some real-world experience, will easily prepare you for the CID exam. I also hope that this text will also become part of your permanent library for reference and reflection—Todd and I have both worked to add value that will transcend the short-term goal of certification.

Review Questions

1.  IP multicast uses which class of IP address?
A.  Class A
B.  Class B
C.  Class C
D.  Class D
2.  Which proprietary protocol is used by Cisco switches to control multicasts at Layer 2?
3.  Which protocol is used by a workstation to inform the router that it wishes to participate in a multicast?
4.  Sparse mode makes use of which of the following?
B.  A rendezvous point
5.  Cisco’s initiative to integrate voice, video, and data is called:
6.  Protocols including RSVP provide which of the following services?
A.  Quality of service
B.  Encryption
C.  Compression
D.  None of the above
7.  Which two protocols provide router redundancy?
D.  VRRP and PIM
8.  HSRP tracking:
A.  Alters the HSRP priority based on the status of another, tracked interface
B.  Allows the administrator to see which packets traversed which router in HSRP configurations
C.  Allows for load balancing in HSRP installations
D.  Allows for ICMP redirect
9.  A black hole network:
A.  Has no default gateway.
B.  Relies on Proxy ARP
C.  Has two routers connected to isolated sections of the same network
D.  Can occur only with token-passing topologies
10.  One reason to create networks based on Layer 3 is:
A.  To avoid spanning-tree reliance
B.  To avoid the need for routers
C.  To allow for HSRP
D.  To support multicast sparse-mode operations
11.  Designing the network with troubleshooting in mind can:
A.  Simplify outage scheduling and isolate systems
B.  Lead to problems
C.  Compel the designer to use VLSM
D.  Negate the use of OSPF
12.  True or false: Most network attacks can be thwarted with a perimeter firewall.
A.  True
B.  False
13.  What is the process of recording customer or user problems, owning the problem, and analyzing that data to improve customer service called?
A.  Auditing
B.  Bug tracking
C.  Case management
D.  None of the above
14.  A designer wants to know at which point additional bandwidth might be required to provide a consistent user experience even during a circuit failure. This problem is answered within the context of which of the following?
A.  Trend analysis
B.  Capacity planning
C.  Case management
D.  Case planning
15.  Virtual private networks require:
A.  Encryption
B.  Compression
C.  Both A and B
D.  None of the above
16.  True or false: Telnet is a secure protocol.
A.  True
B.  False
17.  Networks in the future will likely require:
A.  Bandwidth
B.  Security
C.  Wireless solutions
D.  Intelligent applications
E.  Standards-based protocols
F.  All of the above
18.  The multicast address of would be similar to which of the following MAC addresses?
B.  FF:FF:FF:06:02:01
C.  01:00:5E:FF:FF:FF
D.  01:00:5E:06:02:01
19.  True or false: More than one IP multicast address can use the same MAC address.
A.  True
B.  False
20.  The first three octets of a multicast MAC address start with:
B.  01:00:5E
C.  Depends on the IP address
D.  Is equal to the MAC address of the source

Answers to Review Questions

1.  D.
2.  C.
3.  B.
4.  B.
5.  C.
6.  A.
7.  B.
8.  A.
9.  C.
10.  A.
11.  A.
12.  B.
13.  C.
14.  B.
15.  A.
16.  B.
17.  F.
18.  D.
19.  A.
20.  B.

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