In this post we’ll cover wiring standards and connectors, which are part of the OSI Layer 1 (physical). If you missed the last post of the “A Techie’s Guide to Network Engineering” series, we talked about the OSI Model. Make sure you read that so you have a better understanding of the concepts included in this article.
Introduction to Wiring Standards
When we talk about wiring standards this is where concepts like Fiber, Cat5, Cat6, all of the connectors, etc come into play. I will briefly go over some of the more recent standards but if you want me to cover more connection standards, please leave a comment down below.
Here’s a non-exhaustive list of the most used Cable Types in telecommunications and data transmissions:
Coaxial Cable – This cable has a center conductor made of copper insulated by a plastic jacket with a braided shield over it. It is often used for internal wiring especially in residential homes. Many of us are familiar with this cable because it is used for televisions.
Twisted Pair – Named as such because it has two insulated copper wires twisted together. Twisted pairs could have a metallic shield around them, which is referred to as “Shielded Twisted-Pair” (STP), or could come without shielding, which in this case is called “Unshielded Twisted-Pair” (UTP). UTP is a very common type in residential housing. From a distance perspective, copper has limitations of 1,500 feet for STP and 227 feet for UTP runs, which in an office environment may not be enough. For this reason, fiber may be required. In the next paragraph we’ll review in detail different cabling standards based on this technology.
Fiber-Optical Cable – Fiber optic is the most common medium of transmission for Internet connections. The main difference with copper-based cables is that fiber uses light impulses vs electric ones, so it is immune to Electromagnetic Interferences (EMI) and Radio Frequency Interferences (RFI). Fiber transmission works by sending light impulses, emitted by a LED or a laser, that are carried over plastic (cheaper) or glass (further distance). There are two main categories of fiber connections: Single-Mode Fiber (SMF) and Multimode Fiber (MMF).
Single-Mode Fiber – A typical single-mode optical fiber has a core diameter, made of glass, between 8 and 10.5 µm and a cladding diameter of 125 µm. It uses a laser to generate wavelengths of 1310 nm and 1550 nm within the core. Because light is transmitted longitudinally through the length of the fiber, SMF cables can’t be bent or crimped. SMF is extremely fast in terms of network speed and can carry signals media for longer distances than MMF. For this reason, this type of fiber is the backbone of the Internet, and is also used for transatlantic connections.
Multimode Fiber – A multi-mode fiber has a core size of 62.5 micrometres (μm) and a cladding diameter of 125 μm. MMF also uses LEDs to generate the signal and can support multiple wavelengths transmitted in parallel within its core. In a MMF fiber, light is transmitted at a specific angle, so the signal bounces many times within its core before being received. This makes MMF installations also more flexible, as it can be bent more than SMF. MMF can support data rates for up to 100Gbps but is limited in distance, usually 3000 feet. For this reason, this connection is generally used for cabling within a campus, data center, or building. But it is available in glass or plastic which gives greater flexibility for installation and is less costly than SMF.
Ethernet Copper Cables
In this section we’ll review the copper-based cables that the Ethernet standard supports. Each generation of cabling is abbreviated with the prefix “Cat”, which is the abbreviation for category, followed by a number. Cat cables started with cat1 back in 1979 and the latest one is now on Cat8. The most popular Ethernet cables now installed are Cat5, Cat5E, and Cat6; some old infrastructures could be still running on Cat3.
Cat3 – Is four twisted pairs so a total of 8 wires and has 3 twists per foot rated up to 16MHz. This was popular in the 80s and could push up to 10Mbps ethernet. This is limited to telecom equipment and is obsolete.
Cat4 – The only main difference from Cat3 is that it is rated for 20MHz; this standard quickly became obsolete.
Cat5 – Is rated for 100MHz and speeds up to 100Mbps reliably, while it can handle more, up to 1Gbps (current standard).
Cat5E (enhanced) – This is a Cat5 cable that is enhanced and capable of handling the disturbances on each pair that is typically caused by transmitting data across all four twisted pairs simultaneously. This is considered the base standard still in 2021.
Cat6 – This standard was established back in 2002 and is rated for 250MHz and at smaller ranges (up to 164 feet); Cat6 can handle 10Gbps data rates, which is becoming more requested in the enterprise environments for both horizontal and vertical cabling.
Cat6A – Rated for 500MHz and while it still only supports up to 10Gbps, it can handle twice the distance (332 feet) of Cat6. Also Cat6A cables come as STP or UTP.
Cat7 – Rated for 600MHz is always shielded but also uses a new connector named GG45, which is replacing the RJ45 connector that has been the industry standard up to this point. While GG45 connectors are compatible with RJ45 sockets, these are harder to source. As a result, terminating cables with the GG45 connector is more difficult and costly. Similar to Cat6A cables, also this cable can handle data rates up to 10Gbps and distances up to 332 feet.
Cat8 – Rated for 2000MHz and can transmit about 25 to 40Gbps data rates depending on the distance for up to 30 meters (about 100 feet). This category can use the standard RJ45 connector depending on whether it is Class I or Class II. Cat8 cables are shielded.
There are two main Ethernet connectors for copper-based standards:
RJ45 – This is the standard Ethernet connector that has been around since the late 1980s.
GG45 – While this connector is compatible with RJ45 sockets, it did not receive wide adoption as it was implemented with the Cat7 standard, which was not certified by the IEEE. This led to the creation of the Cat6A standard.
There are many connectors for fiber connections. The two most common ones are:
MT-RJ – This acronym stands for Mechanical Transfer Registered Jack. This was the first fiber connector that was widely adopted in fiber installations. Early networking equipment manufacturers adopted this connector for small form factor devices due to its small size
SC – SC stands for Subscriber Connector. This fiber-optic connector was in great demand in the 2000s due to its low-cost, durability and simple installation for both point-to-point and passive optical networking.
LC – LC stands for Lucent Connector as it was developed by Lucent Technologies in the 1990s. This new style of fiber connector took over the rival MT-RJ as it was easier to terminate and splice, which are two important characteristics for field technicians.
Cat8 or Fiber?
So here is a good question, if Cat8 supports up to 40Gbps speeds, then why is fiber so popular in 40Gbps networks? For two main reasons: distance and time. Cat8 did not become a standard until 2016, well after fiber was introduced. The other issue is that Cat8 has only a range of 100 feet whereas fiber can go over 450 feet. Another reason why companies didn’t move to Cat8 is that fiber supports data rates up to 400Gbps whereas Cat8 can only handle up to 40Gbps in short distances.
How is it applied today? With Cat8 cables regularly available from places like Newegg at reasonable prices, this standard may become more popular than it is now. Still, Cat6 cables are still half their cost, so we still see many Cat6/6A deployments. But the need to run fiber for horizontal and vertical cabling has diminished since Cat8 is significantly cheaper and supports a standard RJ-45 connector.
We’ve come a long way since the era of Cat3 with 10Mbps, with Cat8 able to push up to 40Gbps (4,000x faster/more bandwidth) and SMF reaching 400Gbps data rates. We hope this post helped you learn more about the different wiring standards and connectors available.