Operation and rewiring of a patchbay


Know how to wire a patch bay, how to operate and rewire a patch bay

Introduction :

The patchbay contains all the network equipment necessary for the operation of an enterprise network. What is this equipment and how does it work? How are they connected?

The brewing bay :

Principle :

The patch bay is a cabinet containing the network equipment allowing employees of the same company to access the Internet and make the intranet. There is a router, one or more switches and the boards where the cables arrive which are connected to the wall sockets where the employees connect their computers.

The router :

The router is a layer 3 equipment of the OSI model that describes the operation of network communications and whose layers are :

  • Layer 1: Physical, which corresponds to sending on physical media
  • Layer 2 : Data link, which corresponds to the preparation of the sending on the media
  • Layer 3 : Network, which corresponds to the path selection
  • Layer 4: Transport, which corresponds to the quality of the transmission
  • Layer 5: Session, which corresponds to dialogue control
  • Layer 6: Presentation, which corresponds to the syntax management
  • Layer 7: Application, which corresponds to communication with software.

The router can interconnect two or more networks based on layer 3 addresses, IP addresses. An IP address is a 32-bit address noted as four decimal numbers separated by dots (example: There are two parts to the IP address, one part designating the network and one part designating the hosts. Hosts on the same network can only communicate with hosts on the same network, it is the IP address that routes the packet to the correct recipient.
The router is therefore located in the patch bay and allows Internet access by interconnecting the ISP’s network to the company’s network.

Switches or switches :

A switch is a layer 2 network equipment of the OSI model, it is connected directly to the router in the patchbay and transmits the data that the router sends.
The switch is an intelligent multi-port repeater. The switch does not retransmit all the data on each port, it returns the data intended for a certain recipient by the port where is located the part of the network where is this recipient.

To do this, the switch stores the MAC addresses of each host, this address is the identifier of a network card and is represented on six bytes in hexadecimal. MAC addresses are stored in the switch’s switching table that associates a port with an address. This allows any host on a network to be identified by knowing which switch port it is connected to.

Distribution panels :

In the patch bay there are two types of distribution panels, a telephone distribution panel and a distribution panel that is connected to the wall boxes by cables that pass through the walls.

This last distribution panel connects the cables that leave the ports of the switch or the telephone distribution panel and the cables that are connected to the wall outlets located on the floors of the company building where either a network cable is connected or a telephone cable.

In order to identify the cables passing through the walls and arriving behind the distribution panel in the patch bay, the patch panel(s) (in the case of a large number of employees) are identified with a letter. Each port on each distribution panel is identified by a number. Following this model, the wall boxes where each employee can connect a network cable connected to his computer or a telephone cable connected to his telephone are identified by a letter and a number (the wall box named A1 is connected by cable behind panel A to port 1 and in front of panel A, a cable is connected from port 1 to the switch or to the telephone panel).

The telephone distribution panel connects the ports of the first distribution panel where the telephones arrive to a device called an autocom which is connected to the telephone line and allows several internal telephone lines to be created within the company from a single telephone line. But the autocom is in a different bay.

If the company is located on several buildings and the system is centralized, there may be another distribution panel in the patch bay that connects the patch bays of the other buildings to the main bay using optical fibres. In the main patch bay the optical fibers coming from this patch panel are connected to a device called a backbone that connects the optical fibers to the switches.

Connections :

RJ45 sockets, at switch, router, distribution panel and wall box level, are mainly distinguished as connectors in the patch bay. This allows the use of RJ45 cable, the RJ45 connectors at both ends of the cable fit into the RJ45 sockets. The RJ45 connection reduces interference, reflection and stability problems.

But we can also observe optical fiber. The optical fiber is a transparent wire that conducts light, it is guided in the center of the fiber that is called the core, consisting mainly of silicon. The core is surrounded by the optical cladding, which also consists mainly of silicon. The optical cladding is protected by an envelope, usually made of plastic.

Optical fibre can be used to conduct light between two places several hundred or even thousands of kilometres apart. The light signal coded by a dimmer is capable of transmitting a large amount of information. By allowing very long distance and very high speed communications. Nevertheless the optical fibre even if it is more powerful is much more expensive than the RJ45 network cables.


The audit:

The rewiring corresponds to the rewiring of the bay. To accomplish this task, it is first necessary to audit the machines (computers, printers, etc…) connected to the network. It is then necessary to pass in all the offices in order to note to which wall socket is connected such computer or such telephone. Then list the MAC addresses of each machine. Next in the switch switching table, associate each MAC address to a switch port, to find out to which switch port this computer or this printer is connected. Wall outlets that are unoccupied should also be identified.

Elaboration of documents :

To list the results of the audit, a table is created which includes the switch ports, the machine names, their MAC address and IP address, the wall identifier of the socket where the machine is connected, the floor where the machine is located and possibly the name of the employee who uses the machine. Like this:

On peut également réaliser un tableau regroupant les prises murales inoccupées ainsi que des plans des étages avec les endroits se trouvent les prises.


To better differentiate between cables intended for the computer network and cables intended for telephony, a colour code can be defined for each of them, for example: green for the network and yellow for telephony.

Before disconnecting the cables, first remove the doors on the sides of the switch cabinet. Then only the cables that belong to the network are disconnected by just disconnecting the cables that are connected to the switch. Then it is identified on which port of the telephone patch panel the telephone cables arrive. After that the telephony cables are disconnected and the telephony is reconnected with the new cables first, following the notes taken previously, then the computer network cables, following the table made during the audit, which allows us to be sure of what we are doing. There may be a material called a grommet between the distribution panels that allows cables to be better stored and arranged. You can also use a Rizan which is a plastic material that allows you to tighten the cables and prevent them from hanging. Once the new cables have been installed, all that remains is to replace the doors on the sides and the work is finished.


In short, the patch bay was well thought to be able to contain all the network equipment and thus not be able to disperse the equipment and if there is a problem one knows immediately where to go to see. But it is necessary to take care of it and not to put the cables anyhow to be able to intervene effectively in the event of problem.