Principles of Network Design

Many of the worst network implementations I've seen have failed to follow fundamental network design principles. Here are a few of those basic principles:

The network is the structure that makes the application possible.

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• The design requirements are driven by the application. The network cannot be developed without first understanding the application's characteristics and requirements.

• Network design necessitates the use of skilled professionals. The network design engineer must have extensive practical experience and a theoretical understanding of the technologies and interact with one another. Extensive practical experience should be considered a prerequisite for a design function. You cannot design a network until you have a good understanding of how it works.

The single most significant design tool is a lab. • Rather than on paper, networks are developed in a lab. Because of the intricacy of more advanced internetwork designs, a design is not valid unless it has been validated in the lab. Network modeling software is also untrustworthy. Internetworking necessitates the use of a plethora of complicated technologies that must successfully communicate with one another. In my opinion, the design of big or complex networks cannot be accurately modeled. This type of modeling is only suitable for high-level design. A lab is essential when determining specific technical details.

• Network design typically entails a variety of trade-offs. The underlying design trade-off is usually cost against performance and availability.

• Do not try to replicate the corporate structure. The network design and topology can frequently reflect the organization's business structure. While seeking to mimic this structure should not be discouraged, the network designer should never become imprisoned. A strategy like this can lead to fundamentally poor designs. Keep in mind that the design objectives are the sole crucial driving element behind the design.

• Vendor autonomy. Proprietary solutions should not be encouraged, but they should also not be avoided outright. In some cases, dominant vendors can provide the best answer.

The simplest feasible option should always be used.

• Keep things simple. Unnecessary complexity is likely to raise support costs and make the network more difficult to administer. Furthermore, an additional software with defects is probably being used whenever an overly sophisticated solution is adopted. Increased complexity can only be justified if there is a corresponding benefit or demand.

• Create each network on its own merits. Working from a set of tight and maybe overly generalized design principles or templates is not a good idea. Consider each network on its own merits and avoid just duplicating previous solutions because they appear similar.

• Stay away from the bleeding edge. For all network devices, only use mature and well-tested software and hardware.

• The essential design strategy must not be jeopardized. The architecture may need to be adaptable and change in tandem with the network. This is related to the need for a scalable design. It must not, however, be jeopardized on a fundamental basis. For example, if you are creating a three-layered WAN structure, do not add tier. By adding another layer or mixing and matching' layers, compromises and invalidates the original design. If the original design is continuously compromised for the sake of 'fast repairs,' the design will eventually erode into oblivion, and there will be no longer be a network design in place. If a network design is not fully and strictly implemented as per the original design plan, it is essentially an intellectual exercise. No changes to the original design should be made without the approval of the engineers who created it.

• A good design is characterized by predictability. A well-designed network has predictability and consistency in performance, as well as resilience and scalability.

This is what I mean when I say "building a network a thousand times"! • Create it once or create it a thousand times! If a network was not correctly built from the start, or if that design was compromised, then routine operations like network troubleshooting and adding new devices to the network become design projects in and of themselves. This is because fundamental network changes are not part of any plan unless a legitimate design is followed. As a result, they must be handled as separate projects. There is no predictability, and the impact of any modifications to the network must constantly be analyzed independently if the original plan is diverged from.

• Design necessitates a small but capable team. No single person, no matter how skilled or experienced, should be the only absolute authority in network design. Designing a network entails balancing priorities, making trade-offs, and dealing with a wide range of technological challenges at both the general and detailed levels. A design team requires people with a variety of specializations and strengths. Some people are more concerned with the big picture, while others are more concerned with the specifics.

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