Chapter 7 Virtual Private Networks and MPLS

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Exercise 7.1: Case Study 1

In this case study, your team has been asked to explore the MPLS VPN options for a point of sales service.

The network structure is shown in Figure 7.39. Note that the VAST terminals use 64K (slotted aloha) as an upstream link; they receive 256 K of data streamed down from headquarters. This network is a hub-and-spoke design. The network uses an SNA-polled protocol, equipped with protocol spoofing to reduce polling over the satellite link.

Figure 7.39: Case Study 1

The satellite lease period will be renewable in 60 days, with an increase of service fees by 60 percent. The customer is looking at an MPLS VPN as an alternative, cost-saving service.

Please answer the following questions.

1.	Is MPLS VPN service appropriate, and if so, why?
2.	Which MPLS VPN service is recommended?
3.	How do you justify your recommendation?

Answers

1.	MPLS VPN is best suited for fully meshed network; a cost analysis would determine whether MPLS could produce a savings.
2.	None
3.	No recommendations

Exercise 7.2: Case Study 2

Rag-Tag Books has asked you to assist them in converting from their full-mesh ATM network (shown in Figure 7.45) to an MPLS VPN. Each store has four connections. They are running a variety of ATM traffic, with uncommitted information rate comprising most of their traffic. However, QoS is required for the 10 percent of their traffic that runs the SAP database.

Figure 7.45: Case Study 2

1.	Is MPLS VPN service appropriate, and if so, why?
2.	Which MPLS VPN service is recommended?
3.	How do you justify your recommendation?

Answers

1.	Fully meshed networks could produce a cost justification for MPLS service.
2.	In order to recommend a VPN service, you would need to know whether the interfaces are Layer 2 or Layer 3. Additional information is needed
3.	Further study is needed to make a VPN recommendation. No recommendations were made because the interfaces and requirements ere not clearly defined.

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