Chapter 5: Designing Remote Connectivity (Part05)

References

For additional information, refer to the following resources:

• Cisco Systems, Inc., Product Documentation, http://www.cisco.com/univercd/home/home.htm

• Cisco Systems, Inc., Solution Reference Network Design Guides home page, http://www.cisco.com/go/srnd/

• Cisco Systems, Inc., Enterprise QoS Solution Reference Network Design Guide, http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf

• Cisco Systems, Inc., Frame Relay technical overview, http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/frame.htm

• Cisco Systems, Inc., MPLS and Tag Switching technical overview, http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/mpls_tsw.htm

• Cisco Systems, Inc., Enterprise Architectures, http://www.cisco.com/en/US/netsol/ns517/networking_solutions_market_segment_solutions_home.html

• Cisco Systems, Inc., Cisco product index for routers, http://www.cisco.com/en/US/products/hw/routers/index.html

• Cisco Systems, Inc., Cisco product index for switches, http://www.cisco.com/en/US/products/hw/switches/index.html

• Cisco Systems, Inc., Cisco Feature Navigator, http://www.cisco.com/go/fn

• Cisco Systems, Inc., Cisco IOS Packaging: Introduction, http://www.cisco.com/en/US/products/sw/iosswrel/ps5460/index.html

• Cisco Systems, Inc., Business Ready Branch Solutions for Enterprise and Small Offices—Reference Design Guide, http://www.cisco.com/application/pdf/en/us/guest/netsol/ns656/c649/cdccont_0900aecd80488134.pdf

• Cisco Systems, Inc., LAN Baseline Architecture Branch Office Network Reference Design Guide, http://www.cisco.com/univercd/cc/td/doc/solution/designex.pdf

• Cisco Systems, Inc., LAN Baseline Architecture Overview—Branch Office Network, http://www.cisco.com/univercd/cc/td/doc/solution/lanovext.pdf

• Cisco Systems, Inc., Cisco Business Ready Teleworker Architecture, http://www.cisco.com/application/pdf/en/us/guest/netsol/ns430/c654/cdccont_0900aecd800df177.pdf

Case Study: ACMC Hospital Network WAN Design

This case study is a continuation of the ACMC Hospital case study introduced in Chapter 2, “Applying a Methodology to Network Design.”

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Case Study General Instructions

Use the scenarios, information, and parameters provided at each task of the ongoing case study. If you encounter ambiguities, make reasonable assumptions and proceed. For all tasks, use the initial customer scenario and build on the solutions provided thus far. You can use any and all documentation, books, white papers, and so on.

In each step, you act as a network design consultant. Make creative proposals to accomplish the customer’s business needs. Justify your ideas when they differ from the provided solutions. Use any design strategies you feel are appropriate. The final goal of each case study is a paper solution.

Appendix A, “Answers to Review Questions and Case Studies,” provides a solution for each step based on assumptions made. There is no claim that the provided solution is the best or only solution. Your solution might be more appropriate for the assumptions you made. The provided solution helps you understand the author’s reasoning and allows you to compare and contrast your solution.

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In this case study, you create a high-level design for the WAN portions of the ACMC Hospital network.

Case Study Additional Information

Figure 5-30 shows the existing WAN links and the planned campus infrastructure.

Figure 5-30: Case Study ACMC Hospital WAN Links and Planned Campus Infrastructure

Business Factors

The ACMC Hospital CIO realizes that WAN performance to the remote clinics is poor and that some new applications will require more bandwidth. These applications include programs that allow doctors at the central site to access medical images, such as digital X-rays, stored locally at the clinics. The CIO wants all the remote sites to have the same type of access.

The CIO wants to implement a long-term, cost-effective solution that allows high-bandwidth application deployment on the network and that allows for growth for the next two to five years. The CIO also wants to simplify planning, pricing, and deployment of future applications.

Technical Factors

There is no data about the bandwidth requirements of the new applications. Lab testing would provide better data, but ACMC does not have the time or money for testing. The CIO knows that because TCP adjusts to use the available bandwidth, such that when congestion occurs, there is no way to know how much bandwidth the present applications could ideally use unless extensive lab testing is done.

You discover that your site contact initially supplied you with an out-of-date network diagram. The hospital upgraded the 56 kbps links to 128 kbps a year ago and upgraded the WAN bandwidth at the largest clinic to 256 kbps last month. Therefore, the following is the current state of the WAN links:

• The connection to the largest remote clinic now runs at 256 kbps.

• The connections to two other remote clinics were upgraded from 56 kbps to 128 kbps.

• The two remaining remote clinics have 56-kbps dialup connectivity.

The increased WAN bandwidth you recommend should last for two to five years.

For situations in which you cannot really determine how much WAN bandwidth is needed, one way to proceed is to multiply current traffic levels by a value of 1.5 or 2 per year. However, if the customer does not want to be concerned with needing even more bandwidth in the near future, multiply by bigger numbers. If you expect unknown applications to be added to the network, multiply by even bigger numbers. In this case study, assume that all clinics are to be upgraded to at least T1 access speed. (Pricing structures in many areas might even favor a full T1 over fractional T1 links.)

Case Study Questions

Complete the following steps:

Step 1	Develop a list of relevant information that should be provided in the ACMC WAN Request for Proposal (RFP).
Step 2	ACMC put out an RFP specifying that it requires at least T1 bandwidth at the remote clinics. The responses to the RFP, indicating the technologies currently available to ACMC, are shown in Table 5-8. Calculate the monthly cost of using each of the technologies shown in Table 5-8 by completing the Monthly Cost column in this table. Table 5-8: ACMC RFP Results Open table as spreadsheet Option Technology Speed Price per Month Monthly Cost 1 Leased line: T1 at clinics into T3 at central T1 or T3 $400 for each T1, $8000 for T3 2 Frame Relay: T1 access at clinics, T3 access at central T1 or T3 $350 for T1 access, $7000 for T3 access circuit plus CIR in 5-Mbps increments times $75 plus $5 per PVC 3 MPLS VPN: T1 access at clinics, T3 access at central T1 or T3 $500 for T1 access, $8500 for T3 access 4 High-speed business cable service at clinics T3 Internet at central site 6 Mbps downstream, 768 kbps upstream T3 $90 $4000
Step 3	Which technology do you recommend that ACMC use? (Using either multilink PPP over multiple T1s or using multilink Frame Relay over multiple T1s are also options.) Note To simplify this step, budgetary costs are not included for the routers. Make your choice based on capabilities needed, with the understanding that there is an increasing cost for increasing capabilities and options.
Step 4	ACMC mentions that its images might be 100 MB. Transferring 100-MB images over a T1 connection takes more than 8 minutes (because 100 MB * 8 bits per byte / 1.544 Mbps = 518 seconds = 8.6 minutes). Does this information change your recommendation? Why or why not?
Step 5	The CIO indicates that remote site availability is critical to avoid having servers in the remote clinics. What redundancy or backup WAN strategy do you recommend?
Step 6	Assume that the CIO has chosen to deploy multilink PPP over two T1s for simple, reliable service at each remote clinic, with the 6 Mbps cable service as backup. Select an appropriate Cisco router model to use at the central site and at each remote location. Select appropriate switching hardware for each site, remembering that the ISR routers can use integrated switches. Table 5-9 provides the number of switch ports needed at each of the remote clinics. Tables 5-10 and 5-11 provide a condensed version of the product and module information from http://www.cisco.com/. Table 5-9: Remote Clinic Switch Port Requirements Open table as spreadsheet Remote Clinic Site Number of Switch Ports Needed 1 48 2, 3 24 4, 5 16 Table 5-10: ISR Routers and Port Capabilities Open table as spreadsheet Cisco ISR Model Approx. Mbps of Layer 3 Fast Ethernet or CEF Switching with 64-Byte Packets LAN Ports WAN Ports 851 5.12 10/100 four-port switch 10/100 Fast Ethernet 857 5.12 10/100 four-port switch ADSL 871 12.8 10/100 four-port switch 10/100 Fast Ethernet 876 12.8 10/100 four-port switch ADSL over ISDN 877 12.8 10/100 four-port switch ADSL 878 12.8 10/100 four-port switch G.SHDSL 1801 35.84 10/100 eight-port switch One Fast Ethernet, ADSL over POTS 1802 35.84 10/100 eight-port switch One Fast Ethernet, ADSL over ISDN 1803 35.84 10/100 eight-port switch One Fast Ethernet, G.SHDSL 1811 35.84 10/100 eight-port switch Two Fast Ethernet 1812 35.84 10/100 eight-port switch Two Fast Ethernet 1841 38.40 Two Fast Ethernet. Can add four-port switch with HWIC-4ESW. Can add two HWIC modules: ADSL WAN Interface Card (WIC), G.SHDSL WIC, cable WIC, WIC-1T (one T1), WIC-2T (two T1) 2801 46.08 Two 10/100 Fast Ethernet Four slots: two slots support HWIC-, WIC-, VIC-, or VWIC-type modules; one slot supports WIC-, VIC-, or VWIC-type modules; one slot supports VIC or VWIC-type modules Can add WIC modules listed for 1841, also HWIC-4T (four T1 HWIC) 2811 61.44 Two 10/100 Fast Ethernet Four slots: each slot can support HWIC-, WIC-, VIC-, or VWIC-type modules. Can add WIC modules listed for 1841, also HWIC-4T (four T1 HWIC). Plus, one slot supports NM- and NME-type modules Can use NM-1HSSI (T3) 2821 87.04 Two 10/100 Fast Ethernet Four slots: each slot can support HWIC-, WIC-, VIC-, or VWIC-type modules; can add WIC modules listed for 1841, also HWIC-4T (four T1 HWIC) Plus, one slot supports NM-, NME-, and NME-X-type modules Can use NM-1HSSI 2851 112.64 Two 10/100 Fast Ethernet Four slots: each slot can support HWIC-, WIC-, VIC-, or VWIC-type modules. Can add WIC modules listed for 1841, also HWIC-4T (four T1 HWIC). Plus, one slot supports NM-, NME-, NME-X-, NMD-, and NME-XD-type modules Can use NM-1HSSI 3825 179.20 Two Gigabit Ethernet (10/100/1000) Two NM/NME/NME-X modules or one NMD/NME-XD Four HWIC/WIC/VIC/VWIC slots For relevant NM and WIC/HWICs, see modules listed for 2851 3845 256 Two Gigabit Ethernet (10/100/1000) Four NM/NME/NME-X modules or two NMD/NME-XDs Four HWIC/WIC/VIC/VWIC slots For relevant NM and WIC/HWICs, see modules listed for 2851 Table 5-11: Switch Network Modules for Cisco 2800 and 3800 Series Integrated Services Routers Open table as spreadsheet Module NME-16ES-1G NME-16ES-1G-P NME-X-23ES-1G NME-X-23ES-1G-P NME-XD-24ES-1S-P NME-XD-48ES-2S-P Limitations 2811 and up only Any 3800 2811 and up only Any 3800 2821 and 2851 only Any 3800 2821 and 2851 only Any 3800 2851 only Any 3800 2851 only Any 3800 Ports 10/100: 16 10/100/1000: 1 Small Form Factor Pluggable (SFP): 0 10/100: 16 10/100/1000: 1 SFP: 0 0/100: 23 10/100/1000: 1 SFP: 0 10/100/1000: 1 10/100: 23 SFP: 0 10/100: 24 10/100/1000: 0 SFP: 1 10/100: 48 10/100/1000: 0 SFP: 2 Powered Switch Ports 0 16 0 24 24 48 IEEE 802.3af POE Support No Yes No Yes Yes Yes Up to two of the four-port HWICs can be used for switch HWICs in the Cisco 1841 ISR. Nine-port switch HWICs are also available for Cisco 2800 and 3800 Series ISRs; two of them can be used per 2800 or 3800 router.
Step 7	What design changes would you suggest if the CIO decided that a second router should be used for the backup link at each site?