10 myths about horizontal cable line (1)

/ Part 1/

Horizontal copper cabling is probably the most well-known and discussed component of a structured cabling system among customers, designers, installers and users.

According to the generally accepted idea, it starts somewhere in the horizontal cross-connection (floor distribution node) and ends at the workplace, video camera or Wi-Fi access point. It seems that everything is clear, but over the years of history this important element has acquired a mass of myths, especially regarding connections.

Myth №1. The fewer connections on the line, the better.
Myth №2. Each additional connection on the line reduces the speed on it.
Myth №3. The fewer connections on the line, the lower the costs.
Myth №4. Each additional connection in the line reduces its reliability.
Myth №5. The fewer connections in a line, the longer it will last.
Myth №6. Each additional connection on a line reduces its security.
Myth №7. The choice of cable category for a horizontal line is determined based on the information transmission speed of the ports of the connected active equipment.
Myth №8. The maximum length of a horizontal line is 90 meters.
Myth №9. The cable in the line must be of the same type and category.
Myth №10. A new horizontal cable line can always be laid in the right place.

From the history of one organization (part 1)

In the early 90s, in computer networks, coaxial cable (bus topology) began to be replaced by twisted pair cable (star topology). And in organization “X,” computers began to be connected to concentrators (hubs) using cable segments crimped on both sides with RJ45 connectors. This solution has many visible advantages. No extra connections (no extra connections at all) – this seems like a great solution and is ideal for minimizing the number of connections on a line. And the savings are immediately visible on every horizontal line; there are no extra costs for sockets, socket ports, cross-panels, cross-panel ports and a couple more patch cords. And at that time it was about fifty dollars. On two hundred lines, that’s a savings of about ten thousand dollars. Of course, ten thousand dollars is a powerful argument that can tip the scales.

Time passed. And it turned out that users were not satisfied with the direct connection of a horizontal cable line to the computer. At work, he felt like a prisoner, chained, and his movements became limited. And the connectors broke with enviable regularity – either the cleaning lady touched the cable with a mop, or someone got caught on it. The connector is broken, there is no connection to the computer network, necessary and urgent matters await. As it turned out, the losses of organization “X” from downtime were many times greater than the initial tempting and tempting savings (myth №3 has been questioned).

So in organization “X” computer sockets appeared on the walls and computers began to connect to the local network using patch cords. Another connection appeared in the horizontal line (the first intermediate connection appeared in the horizontal line), and office inhabitants began to live better (myth №1 was dispelled) and the speed of access to the network did not decrease (and there was a hole in the body of myth №2). The reliability of connecting the workplace to the computer network has increased, the number of disconnections from the network and their time have been reduced by an order of magnitude, or even two (myth №4 has been dispelled).

Time passed. Office telephone exchanges became available. Organizations began to acquire them one after another for themselves. Organization “X” also received an office telephone exchange and new telephone sets for it. Telephone sets were assigned to premises and employees. Now the next task was to lay telephone cables from the new PBX to the telephone sets. Construction work, noise, dust, disruption of organization, time, money.

They suggested using existing twisted pair cables to connect phones. The local network then used two pairs for its operation, and two pairs in the cable were free. And it was possible to connect two devices with one cable: computer + computer; it was “terminated” to the cross-panel – one cable to two ports of the cross-panel. And a cable in the workplace area to a two-port outlet. And now the “meaning” of a port on a socket is determined by what is connected by a patch cord to its port on a cross-panel, a hub port, or an office PBX port.

Another intermediate connection (second) appeared in the horizontal line, this time from the side of the local network hub. From that moment on, twisted pair cables ceased to be part of the local network and became part of an independent independent engineering system called a “structured cabling system.”

With the connection of a horizontal line to the cross-panel, a new opportunity appeared – the socket port could be either “computer” or “telephone”.

The life of office residents has become better (myth №1 has been debunked again) and the speed of network access has not decreased (the second hole in the body of myth №2).

And of course, the second connection immediately brought significant savings – there was no need to finance the installation of telephone cables (let’s finish off myth №3).

Time passed. Organization X begins to modernize another building on its campus. The renovation of the rooms is being completed, it’s time to lay the cables, and where the interfloor passage will be, the decision has not yet been made, the struggle for the premises is still going on. What to do? Someone came up with the idea of installing a 110 cross-panel under the ceiling at the entrance to each room and connecting cables coming out of the room to it. And then, when the floor sneaker appears, run its cables from it to the entrance to each room, or rather to its entrance 110 cross-panel. And then connect the cables coming out of the room and the floor cross-connect cables to the ports of the cross-panel 110 (one line of such a cross-panel is ready to accept 6 twisted pairs). And then for the cable system of the room it will not matter where the interfloor cross is located.

A third intermediate connection appeared in the horizontal line. Each room has become self-sufficient and autonomous. It has become better (let’s finish off myth №1).

The speed of network access has not decreased (another hole in the body of myth №2).

Twisted pair cable work on this floor caused less friction and collisions with neighboring workers and was completed faster, the cost of developing the floor was lower than usual (cost reduction instead of increase – we continue to finish off myth №3).

Time passed. The purpose of some of the premises has changed, some of the premises have been rented out. Construction and finishing work was carried out here. And it turned out that as a result of construction work, some sockets in these rooms were destroyed. Along with the outlets, their horizontal cable lines also died.

Subsequently, it turned out that not all horizontal lines died in this devastating construction hurricane; there were survivors among them. What united the surviving horizontal lines? How were they different from others? It turned out that they all did not enter the rooms immediately, but through intermediate 110th cross-panels installed under the ceiling in front of the entrance to the rooms.

That is, the third breaking point saved them from death and extended their lives. Horizontal lines with two break points died (buried), but lines with three break points remained (the collapse of myth №5 is evident). This third break point subsequently became known as the “consolidation point.”

And again, an additional break point demonstrates the presence of an economic effect (we complete myth №3).

Premises have their own life cycle; it is noticeably shorter than the service life of the building and the life cycle of the structured cabling system. Over time, it became clear that it was not advisable to lay cables directly into the room. It is better to introduce them into the room through the break point (through the consolidation point). The economic benefits of this approach are observed both at the stage of creating a structured cabling system and at the stages of its operation and modernization.

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End of part 1. To be continued.

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Article created by RJ45
Literary editor Eugene.P
P.S. This illustration was created by artist Peter Zakharchenko
especially for this publication.