Whether you are using fiber internet or an xDSL (ADSL or VDSL) internet, the RJ45 socket is a part of our life. But the RJ11 is a whole different world. So what’s the difference between them?
What is RJ45?
A registered jack (RJ) is a standardized physical network interface for connecting telecommunications or data equipment. The physical connectors registered jacks use are mostly modular connector and 50-pin miniature ribbon connector types. The most common twisted-pair connector is an 8-position, 8-contact (8P8C) modular plug or jack applied for ethernet-based local area networks (LAN), often referred to as an RJ45 connector. Four of these pins are used to send and receive data, while the other four are used for other technologies or devices that need to be powered.
We definitely use the RJ45 connector somewhere in our lives. So where is it? In the ethernet cable from your modem to your computer, television or media box, and in the ethernet cable from the fiber internet terminator to your router.
The ends of the ethernet cables used for these purposes today consist of RJ45 connectors. The LAN and WAN ports on the back of your modem are the sockets these ports enter. In addition, the ethernet port on your computer is one of the sockets that the same connector will enter.
Although the ports are the same, the ethernet cables from our modems to our devices and the WAN cables from fiber termination devices have different configurations. These are called T568A and T568B. The T568B layout is the layout we encounter in standard ethernet cables, while the T568A is the layout we encounter in termination devices.
When you buy an ethernet cable that isn’t ready, you need the aforementioned schematics to plug the RJ45 end. As we mentioned above, if you are going to use it as a normal ethernet cable, you should apply the standard called T568B. If it is T568A, the schematic layout you will use when you want to extend the cable from the terminating devices.
What is RJ11?
Although RJ11 looks very similar to RJ45 in appearance, it is structurally completely different. The first thing that catches the eye is its size and number of pins. Unlike RJ45, the RJ11 port has a 6P2C or 6P4C configuration and is used to wire a single telephone line. The biggest difference between RJ45 and RJ11 lies in the number of wires in their connectors. When you take a closer look you will see that RJ45 has 8 wires inside, while Rj11 has 4 wires and RJ45 is bigger than RJ11.
As we mentioned above, with 2 or 4 of the 6 available ports, it supports applications with limited bandwidth, including RJ11 plug, telephone lines and ADSL connections. On the contrary, 8 contacts will allow more bandwidth. Thus, RJ45 can be used for intensive applications such as ethernet and can support up to 10Gbps of bandwidth.
We can tell the difference between RJ11 and RJ45 as follows;
| Configuration | 6P4C (6 positions, 4 connectors) | 8P8C (8 positions, 8 connectors) |
| Shape and Size | Compact, square-shaped | longer, rectangular |
| Band width | RJ11 connectors (2 pins) can support about 24 Mbps | RJ45 connectors can support 10 Gbps over ethernet. |
| Usage areas | Phones, ADSL lines. It is mostly used for audio applications. | Computer networks. RJ45 is typically used to connect cable modems with ethernets or Wi-Fi routers. |
Does the type of connector used affect performance?
In particular, there are multiple types of RJ45 connectors. The classic and most common type are connectors with a plastic body. In addition, there are connectors with metal bodies and gold-plated ends. However, we cannot say that they show a difference in performance. Their only advantage is that they do not break after any impact and their latches remain intact.
For this reason, quality cables, especially cables with a category of CAT6 and above, now have metal-encased RJ45 ports. These are generally referred to as EtherCON RJ45.
What does CAT mean?
When you buy an Ethernet cable or look at the Ethernet cables coming out of the boxes of our modems, we see phrases such as CAT5, CAT5E or CAT6. These phrases are terms that specify the standard of the ethernet cable and show what features it offers.
If we define it in an easy way; The CAT standard with a low number represents the cables that are weak in terms of bandwidth and signal loss, while the CAT standard with a high number represents the cables with high bandwidth and little or no signal loss.
In other words, we can say that it is a problem-prone cable type with slower speed compared to CAT 5, CAT 5E and CAT 6 standards. CAT 6, on the other hand, offers higher speed thanks to its bandwidth, while preventing signal loss thanks to the isolation between channels. This means a smoother internet experience.
In addition, the length of these cables is also a situation that directly affects your experience. For example, let’s say you are going to connect the internet from your modem to the TV in your living room. When this cable is too long, it will still cause signal loss and cause various problems such as low internet speed and connection problems. The ideal length is the longest you need. In other words, more long cable should not be preferred than necessary.
You can use the table below to better understand and compare Ethernet cable categories. In addition, this table will help you choose the type of cable according to the speed of the internet you are using.
| Category | Insulation | Max. connection speed | Max. band width |
| CAT 3 | No | 10 Mbps | 16 MHz |
| CAT 5 | No | 10-100 Mbps | 100 MHz |
| CAT 5E | No | 1.000 Mbps – 1 Gbps | 100 MHz |
| CAT 6 | By cable type | 10 Gbps up to 55 meters | 250 MHz |
| CAT 6A | No | 10 Gbps up to 55 meters | 500 MHz |
| CAT 7 | No | 100 Gbps up to 15 meters | 600 MHz |
| CAT 7A | No | 100 Gbps up to 15 meters | 1.000 MHz |
| CAT 8 | No | 40 Gbps up to 30 meters | 2.000 MHz |
CAT 3 ve CAT 5
CAT 3 and CAT 5 ethernet cables are the slowest and most problematic categories. Although CAT 5 cables are still widely used, CAT 3 cables are now retired. If you want an internet or local area connection of 100 Mbps or higher, you should stay away from both of these categories.
CAT 5E
CAT 5E is a revised version of your CAT 5 version, that is, a slightly improved version. There is no physical difference between them. However, manufacturers began to manufacture CAT 5E cables under stricter testing standards to eliminate unwanted signal transfers between communication channels (cross talk). CAT 5E is currently one of the most widely used cable types due to its low cost of manufacture and supporting higher speeds than CAT 5 cables. Although it supports 1000 Mbps speed, its biggest disadvantage is that it does not have any insulation.
CAT 6
The CAT 6 standard has a much larger bandwidth than all previous standards. These cables, which are insulated with foil and braided structures according to the manufacturer’s preference, aim to minimize signal loss. In addition, cables with this standard come out of the boxes of many modems today.
If you want to have a smooth internet experience, CAT 6 is the best affordable solution.
CAT 6A
CAT 6A is a bandwidth upgraded standard over CAT 6. The bandwidth, which is 250 MHz with CAT 6, increases to 500 MHz with CAT 6A. In this way, this cable is able to maintain high speeds. In addition, another big advantage of this standard over CAT 6 is that it comes insulated as standard.
CAT 7
CAT 7 is a much more advanced standard than any previous standard. The increased bandwidth is especially suitable for those who constantly transfer files over local networks. For example, you are in a studio producing video content and you need to copy the files to different locations. With this cable, you can reach 100 Gbps speed. This means 12.5 GB of data transfer per second.
CAT 7 cables come with GigaGate45 connectors instead of RJ45 connectors like their predecessors. Although this connector is backwards with RJ45, it still has a structure that can cause problems. For this reason, it is useful to check compatibility when choosing for your old devices.
CAT 7A
CAT 7A retains the speed offered by CAT 7, but increases bandwidth, promising a better experience in two-way communication. As in CAT 7, it still has limits on support. This category, which is unnecessary for home users in every way, is designed for use in large projects or businesses.
CAT 8
Next is the most advanced ethernet cable standard. CAT 8 is the most advanced type of ethernet cable currently being studied but still available. With this cable type, data transmission over longer distances becomes possible. High bandwidth also provides a great advantage in two-way communication.
CAT 8 is also the only cable type that supports IEEE (Institute of Electrical and Electronics Engineers) standards.
