How do I design SCS

This article was born in response to the article “Ideal Local Area Network” . I do not agree with most of the author’s theses, and I want to not only refute them in this article, but also put forward my theses, which I will defend in the comments later. Next, I will talk about several principles that I adhere to when designing the local network of any enterprise.



The first principle is reliability. An unreliable network will always be more expensive due to the cost of its maintenance, losses from downtime and losses from outside interference. Based on this principle, I always design the main network only wired, and if necessary, an additional wireless network (guest network or a network for mobile terminals). Why is a wireless network less reliable? Any wireless network has a number of security, stability, and compatibility issues. Too many risks for a serious company.



Reliability also determines the network structure. Topology "Star" is the ideal to which you want to strive. Zvezda reduces the number of switches needed, the number of vulnerable trunk lines, and simplifies maintenance. How much easier it is to look for a problem in one switch than in several scattered around cabinets, as the author of the aforementioned article suggests. Not for nothing the phrase "zoo switches."



But often in practice one still has to use either the "fractal star" or "mixed topology" topology. This is due to the limitation of the distance from the switching equipment to the workstation. That is why I believe that optical networks will completely replace twisted pair over time.







If it is not possible to place all the switches in one place, then it is preferable to use a mixed topology, because all trunks will go on different routes, which will minimize the likelihood of simultaneous damage to several highways.



Speaking of trunks. Switches connected by trunk lines should always have a backup channel, then if one line is damaged, the connection between the nodes will remain and no connection will be disconnected. It will be possible to slowly drag the damaged wire. Therefore, for trunks, even at short distances, you can use a faster and thinner optical patch cord.



The second principle of constructing SCS is rationality and practicality. It is rationality that does not allow the use of “modern” optics in connecting workstations and other network devices. As the author of the aforementioned article correctly noted, everything is working on a twisted pair cable now. It is very practical. But on optical channels without additional devices, so far little can work. And each additional device is not only a vulnerability but also an additional cost. But still, this is the future. Someday, when almost every device will have an integrated optical port, optics will completely replace the twisted pair.



Rationality and practicality can also be manifested in the number of sockets rj45 in the workplace. It is practical to use 2 sockets per place. The second line can be used, for example, to connect an analog (digital) telephone, or simply be a backup. This is how SCS is usually designed for large companies. For small and medium-sized businesses, it is more rational to use one computer outlet per workstation, since ip phones basically have two ports - an incoming link and a second for connecting a computer through it. For network printers, it is always advisable to design a separate workstation, and arrange it as conveniently as possible for all employees using it, for example, in corridors. To decide which is more important - rationality or practicality should be a person competent in it, since we all know very well what management usually chooses.



There is another important point that I would refer to rationality and practicality. This is a reasonable redundancy. It is more practical to have as many jobs in offices as there can be employees, rather than how many people are currently working there. Here again, a competent employee who has an idea of ​​the financial capabilities of the company and who understands that in the case of new Wishlist should solve it, he will have to solve the problem.



And of course, the choice of equipment and materials can be attributed to the principle of rationality and practicality. For example, if the company is small and does not have the ability to keep a competent network administrator on staff who can work with L2 switches, it makes sense to use unmanaged switches, while backup trunks should still be, albeit not active. You do not need to save on materials. To use copper-plated instead of copper twisted pair, then it is guaranteed that in a couple of years they will encounter the problem of poor connections. To refuse patch panels, factory patch cords and organizers means to get confusion in the cabinet after some time, constantly “falling off” links and oxidation of the connectors. Do not save the same on the server cabinet. The large size will not only allow you to place more equipment in it, but also facilitate its maintenance.



Do not save on patch cords. Good factory patch cords should be both in the workplace and in the server cabinet. If you calculate the time spent on crimping the connectors and the cost of materials, then buying a factory patch cord will be cheaper. In addition, the cable will be taut, the connectors may turn out to be bad, the connectors will oxidize much faster, the crimping tool may turn out to be bad, the eye may blur and there are many more reasons not to use a homemade patch cord.



In my opinion, if there is no need for a workstation to work at 10G speeds, it is more rational to use a twisted pair of category 5e and not the 6th, because it is not only cheaper, but also thinner, more flexible and therefore easier to install.



And finally, the third principle is orderliness. The larger the network, the more important the order in it. Sockets and ports of patch panels must be numbered. Numbering usually begins at workplaces from left to right from the entrance to the room. Be sure to have an approved floor plan with the location and numbering of outlets.

It is for orderliness and not for the physical separation of networks that patch panels are used. If the author of the article “more than once already mentioned” assumes that there is nothing special to commute in his closet, then we cannot afford this.



That's all. These three basic principles define any of my SCS projects. In this article, I could not touch on everything, I probably missed a lot, somewhere it’s probably wrong. I am always ready for a constructive discussion if they give me an invitation or in personal correspondence.