CCDA - 640-441 DCN

Case Study:

University of Distance Learning (UDL):

University of Distance Learning Head quartered at Wellington, has been imparting adult education and vocational training to its students over the last several years. The training methods include contact classes at fixed intervals in a year and the course material sent to its students through land mail. UDL has Regional Centers (RCs) at 4 places and Study Centers (SCs) at 12 places, spread over the country.

The UDL's current network consists of leased 64KBPS lines among the Head quarters and the RCs in full mesh configuration. The SCs are connected to the regional centers through dial-up ISDN connections. The head quarters has Novell servers, and NT servers at the Head quarters. The regional centers have Windows NT 4 Server with several work stations. All the Windows work stations run standard MS office applications. The WAN circuits are used extensively and the usage is recorded close to 75% on all WAN segments consistently over a period of time.

Now that the UDL has budgeted for providing two-way distance learning application, by means of video conferencing at all the RCs and a few selected SCs. It is also required to implement two way voice (Through the use of VOIP) at all the RCs and SCs. The Head Quarters is having two Novell 4.11 file servers, one Windows NT 4 Server and 56 Windows 95 computers. All the PCs are on two LAN segments, which in turn connected to a switch. The Novell and NT Servers are connected to the LAN through a switch. Two network printers are also connected to the LAN. It is observed that the LAN traffic in both the segments is exceeding 40% at times when there is peak load. All the administrative functions are carried out at the Head Quarters.

Regional Center at Greymouth has one Windows NT 4 server with 28 Windows 95 computers, one network and one local printer attached to one of the PCs and accessible over the LAN. Regional centers at Timaru, Gisborne and Ashburton have 14 Windows 95 computers with one network printer each. All the Windows computers run standard Microsoft office suite of applications. All these computers are on 10BaseT LAN. The LANs are connected together through routers at each of the regional centers, in a full mesh configuration together with Head Quarters at Wellington. The regional centers, in turn are connected to respective study centers in star configuration, with each regional center acting a hub to respective study centers. Each Regional center serves 4 study centers. It is planned to increase the number of regional centers to 6 and study centers to 20 over the next 2 years.

UDL is also considering installing a Web server as an option, at the head quarters. However, the director is concerned about the security aspect and asked for a hardware based, full featured Cisco firewall to give maximum security. It is also required that the project, once completed will have a centralized network management in place. It is also proposed as an option, to have an e-mail server such as Microsoft exchange installed such that there is a unified electronic mailing system in place. It is required to have a routing protocol that supports multiple routed protocols and enabling future expansion. The whole project is proposed to be completed and operational by the first quarter of next year. The director is interested in a demonstration of distance learning application using video conferencing.

Q1. What is the primary application that the UDL intend to run after the up gradation?

A. Distance learning by video conferencing

B. Web server

C. GroupWare

D. MS office applications

Ans: A

Exp: The primary objective of up gradation is to provide distance learning application by means of video conferencing. The other optional requirements are e-mail and, Web server applications.

Q2. What are the routed protocols used in the existing network?





Ans: A,B

Exp: The network has Novell and NT servers in the existing network. IP and IPX are two routed protocols that are likely to have been used in this network.

Q3. Which routing protocol you suggest, considering that it should be scalable, support multiple routed protocols?





Ans: C

Exp: EIGRP supports multiple protocols, scalable, and can also be configured for load-balancing over unequal paths.

Q4. Is it recommended to segment the Ethernet LAN at head quarters reduce traffic to less than 40%, considering that it is running close to 40% now?

A. Yes

B. No

Ans: A

Exp: It is recommended to reduce the LAN traffic to comfortable levels (say around 20% of its capacity). A LAN segment running at 40% is considered to be running at its full capacity.

Q5. The existing WAN traffic connecting the Head Quarters with RCs is within the comfortable levels.



Ans: B

Exp: WAN traffic over 70% is considered to be above threshold.

Q6. Considering that the proposed network will use distance learning application with video conferencing, which WAN protocol do you propose?

A. X.25

B. Async

C. Frame Relay


Ans: D

Exp: The choice is between Frame Relay and ATM. Considering that the video application is time sensitive, it is preferable to have ATM over Frame Relay. It is possible to have better control over the traffic with ATM.

Q7. In the given example, what is the recommended bandwidth among the Head Quarters and RCs?

A. 64 KBPS leased line


C. DS1

D. One ISDN BRI channel

Ans: C

Exp: The distance learning application uses two way video conferencing. It is also proposed to have VOIP. A leased DS1 (1.544 MBPS) between the Head Quarters and RCs and use of ATM will adequately take care of the proposed expansion.

Q8. Which Cisco device could be suggested to provide adequate security firewall?

A. Centri


C. Cisco IOS router firewall


Ans: B

Expl: It is proposed to provide hardware based dedicated firewall for protecting the LANs from the Web server. Centri firewall is software baed firewall. Cisco IOS firewall is also not a dedicated firewall with advanced features. PIX firewall is recommended solution.

Q9. While characterizing the existing network, it was found that the routers were dropping 5% of the frames from the output queue of majority serial WAN ports. Does this indicate any problem?

A. The existing WAN links are running at more than the capacity, the link speeds need to be augmented.

B. The existing WAN links are running at normal capacity

C. This doesn't indicate any problem with the WAN links.

D. The load on WAN circuits need to be balanced.

Ans: A

Exp: A drop of 5% of frames from the output Queue indicate that majority of WAN links are choking at full capacity. WAN bandwidth need to be augmented.

Q10. Which command can be used to check whether the WAN ports on the routers are dropping packets?

A. sh processes

B. sh protocols

C. sh interfaces

D. sh buffers

Ans: C

Expl: sh interfaces command indicate any drop in frames from the output queue. sh processes command indicate the CPU utilization, and sh buffers indicates if there is any problem with buffers.

Q11. Which Cisco Network Management System do you propose for the network?

1. CiscoView

2. CiscoWorks

3. Cisco Centri

4. ConfigMaker

Ans: B

Expl: CiscoWorks is recommended as this would allow comprehensive and powerful set of configuration, monitoring, and diagnostic applications. It is also SNMP based. CiscoView is part of Cisco works suite of applications.

Q12. Which is the critical process in the proposed network.

A. Implementation of e-mail server

B. Ineterconnecting existing LANs

C. Implementation of distance learning application using video conferencing

D. Implementation of Web server

Ans: C

Expl: The important application is distance learning application and two way video conferencing. The network design, bandwidth allocation are greatly influenced by this application.

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