Network design underlies the performance of your enterprise IP network. This four part guide by Cormac Long offers you a comprehensive roadmap to designing IP-based networks, from the basic principles involved to the more complex finishing touches.
 Part 1: Fundamental principles | |
A competent network design is the foundation upon which all successful network implementations are built. This is the first of four articles that focus on the design of IP-based networks, due to the prevalence of IP as the de-facto standard desktop protocol. The applications that a state of the art IP network supports have become increasingly diverse in nature. Along with traditional data applications, IP has become a transport mechanism for real-time applications such as voice, video and multimedia. As a result of the heterogeneous nature of modern applications, the design of IP internetworks has never been more challenging. This article discusses the fundamental principles that should be followed when designing a network. Subsequent articles will deal with specific LAN and WAN technology with which a proficient network design can be implemented.
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| Part 2: The IP addressing plan | |
The IP addressing plan is the foundation upon which a successful logical design is built. This section explains how to formulate a scalable IP addressing plan that can support the network as it grows. The use and importance of key tools such as variable length subnet masking and route summarization are explained. Choosing the appropriate routing protocol is equally critical. The parameters used to evaluate the suitability of a routing protocol are explored and discussed. The different characteristics of IP routing protocols are described along with the operation of industry standard protocols such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF).
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| Part 3: Designing the wide area network | |
The wide area network (WAN) is the single biggest contributor to a corporate network's cost of ownership. Therefore this is the area where the cost versus performance trade-off is most pronounced and most critical. This article explores the various alternatives that must be evaluated when choosing and designing a WAN infrastructure. The different topological and technological options are discussed in terms of how they relate to the fundamental WAN design goals. Traditional technological alternatives that include synchronous serial lines, frame relay, and ATM will be discussed along with more state of the art options such as DSL and MPLS.
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| Part 4: LAN design | |
This final section of the IP network design series relates to the issues encountered with campus LAN design. The benefits of Ethernet switching over a traditional hub environment are first explained. The motivation behind the deployment of virtual LANs (VLANs) is explored along with the issues faced when planning and configuring VLANs. This article also discusses techniques for ensuring a scalable and resilient campus network design. The Spanning Tree Protocol is also addressed and how it can be optimised on a large switched network. Finally, the design issues associated with an IP Telephony rollout are covered in the concluding section of this article.
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