Year 2 - Chapter 10/Cisco 4 - Module 3 WAN Design

1. Year 2 - Chapter 10/Cisco 4 - Module 3WAN Design Cisco Press: CCNA Instructor’s Manual

2. WAN Options Cisco Press: CCNA Instructor’s Manual

3. WAN Design Requirements • Optimize WAN Bandwidth • Minimize Costs • Maximize the Effective Service to the End Users Cisco Press: CCNA Instructor’s Manual

4. Pressures on Existing Networks • Increased use of client/server and multimedia applications. • Increased use of enterprise servers. • Applications increasingly require distinct network qualities of service. • Increased network connections for remote users, mobile users, international sites, customers/suppliers, and the Internet. • Growth of corporate intranets and extranets. • Internet and "push" technologies. Cisco Press: CCNA Instructor’s Manual

5. WAN Design Goals • Application availability • If the applications are not available to network users, the network is not doing its job. • Total cost of ownership • To properly implement the WAN infrastructure to optimize application availability and allow the cost-effective use of existing network resources. Cisco Press: CCNA Instructor’s Manual

6. Secondary Design Goals • Functionality Does the network work? Can the users do their job? The network must provide acceptable and reliable connectivity to the organizational resources that user needs. • Manageability Can the network be monitored and managed conveniently and efficiently by network professionals? If routine monitoring and maintenance is not convenient, it tends to be skipped. • Scalability Can the network expand and contract with changes within the organization? The original design should be able to adjust without having to be redesigned. Cisco Press: CCNA Instructor’s Manual

7. Steps in Designing a WAN • Gathering Requirements • Analyzing Requirements • Sensitivity Testing Cisco Press: CCNA Instructor’s Manual

8. Types of Requirements • Business requirements • Organizational requirements • Technical requirements • Performance requirements • Application requirements • Network management requirements • Security requirements Cisco Press: CCNA Instructor’s Manual

9. Business Requirements • Looks only at the organization’s business model • Does the design benefit or hinder their way of doing business? • Does the design provide a competitive advantage? • If so, which costs are reduced and by how much? • Is the organization an industry leader or industry follower? • Does the design scale consistent with the organization’s expected growth? Cisco Press: CCNA Instructor’s Manual

10. Organization Requirements • Who has bought into this project? • Is it supported high enough in the organization to make sure that resources and attention will be committed? • Is there an existing budget? • Is it reasonable for what needs to be done? • Who must approve any changes or budget increases? • Is there an existing timeline for the project? • Is the timeline reasonable? Cisco Press: CCNA Instructor’s Manual

11. Technical Requirements • Performance Requirements • Application Requirements • Network Management Requirements • Security Requirements Cisco Press: CCNA Instructor’s Manual

12. Performance Requirements • Defining Acceptable levels of performance measured in: • Response Time • Bandwidth utilization • How to ensure that those levels can be preserved through both network growth and increased utilization. Cisco Press: CCNA Instructor’s Manual

13. Application Requirements • Which centralized applications are currently used on the network? • Who needs access to these applications and where are they located? • What new applications are being added in the new design? • What are peak loads? • Per day, per week, per month, per year? • Can any high bandwidth applications be rescheduled to run outside of normal business hours? Cisco Press: CCNA Instructor’s Manual

14. Network Management Requirements • How much traffic to capture • How much statistics to gather • Where to measure network utilization • Remote configuration Cisco Press: CCNA Instructor’s Manual

15. Security Requirements • How is network security currently handled? • Does the organization understand the need for security? • Will there be additional exposure as a result of the new design? • How will the additional security and related training be handled? • Defining the level of security that the customer could realistically pay for and live with. Cisco Press: CCNA Instructor’s Manual

16. Methods to Obtain This Information • To determine user community profiles • What different user groups require • Interviews • Least formal approach • Focus groups • Surveys • Gathering statistically valid input • Human factors tests (lab environment) • Most expensive, time-consuming, and possibly revealing method Cisco Press: CCNA Instructor’s Manual

17. Analyzing Requirements • How can the new design meet each of the following: • Business requirements • Organizational requirements • Technical requirements • Performance requirements • Application requirements • Network management requirements • Security requirements Cisco Press: CCNA Instructor’s Manual

18. WAN Sensitivity Testing • Pilot—Small-scale test network (lab) • Generally proving the technology works • Often includes borrowed resources • Prototype—Larger scale test network • Proves all aspects of the entire design • Purchasing enough resources to outfit a test branch or test location (one classroom in a school upgrade) • Computer design modeling programs • Cisco’s Netsys Baseliner, a simulation-based planning and problem-solving tool for network managers, analysts, and designers Cisco Press: CCNA Instructor’s Manual

19. Three-Layer Hierarchical Model Cisco Press: CCNA Instructor’s Manual

20. Benefits of a Hierarchical WAN Design • Scalability • Ease of Implementation • Ease of Troubleshooting • Predictability • Protocol Support • Manageability Cisco Press: CCNA Instructor’s Manual

21. Functions of Hierarchical Layers • Core layer • Provides optimal transport between sites • Distribution layer • Provides policy-based connectivity • Access layer • Provides workgroup and user access to the network Cisco Press: CCNA Instructor’s Manual

22. Core-Layer Functions • If there is a failure in core every single user can be affected. • Speed and latency are driving concerns here. • Things that we know we do not want to do: • Do not do anything to slow down traffic (VLANs, ACLs, Packet Filtering) • Do not support workgroup access here • Avoid expanding the core when the internet work grows: Give preference to upgrade over expansion. Cisco Press: CCNA Instructor’s Manual

23. Core-Layer Functions • Things we know we want to do: • Design the core for high reliability • Consider data link technologies that facilitate both speed and redundancy (ATM, FDDI) • Design with speed in mind. The core should have very little latency. • Select routing protocol with lower convergence time (OSPF) Cisco Press: CCNA Instructor’s Manual

24. Distribution Layer • The distribution layer is where much of the action is • The emphasis here is control. • Items that should be done at the distribution layer: • Implement tools such as access lists, packet filtering, and queuing. • Implement security, and network policies, including address translation and firewalls. • Redistribution between routing protocols • Routing between VLANs. Cisco Press: CCNA Instructor’s Manual

25. Access Layer • Controls user and workgroup access to internetwork resources. • Some of the functions to be included at this layer include: • Continued (from distribution layer) access control and policies. • Creation of separate collision domains • Workgroup connectivity into distribution layer. Cisco Press: CCNA Instructor’s Manual

26. Three categories of customer Problems • Media Problems: Problem relating to contention for use of the media itself. Examples include collision rates and utilization rates. • The recommended solution is to use LAN switching to separate collision domains. • Protocol Problems: Protocol problems result when protocols designed for workgroup environment are used in significantly larger environment. • The recommended solution is to use routing to separate broadcast domains. • Transport Problems: Result when extreme transport problems are placed on the network. For example many IS departments are required to implement video conferencing and video streaming solutions. • Using ATM solves transport problems. Cisco Press: CCNA Instructor’s Manual

27. Connectivity in a Three-Layer Model Cisco Press: CCNA Instructor’s Manual

28. Server Placement Cisco Press: CCNA Instructor’s Manual