Introduction to various types of network cables, what are Category 5 and Category 6 cables?

1. Network cable overview

The network cable usually referred to is an Ethernet cable, that is, a twisted pair. It is a data transmission line composed of two mutually insulated metal wires twisted into a twisted pair at a certain winding density, and then multiple pairs of wires are combined. This article mainly introduces the classification and differences of twisted pair cables.

2. Classification by electrical properties

According to electrical properties, twisted pair cables can be divided into: Type 1 (CAT1), Type 2 (CAT2), Type 3 (CAT3), Type 4 (CAT4), Type 5 (CAT5), Type 5e (CAT5e), Type 6 (CAT6), Type 6a (CAT6), and Type 7 (CAT7). Among them, the most common and used in Ethernet transmission are Category 3, Category 5, Category 5e, Category 6, and the latest Category 7. The former has a thinner wire diameter and the latter has a thicker wire diameter. They are introduced below:

(1) Class I wire:

The highest frequency bandwidth of the cable is 750kHZ, which is used for alarm systems or is only suitable for voice transmission (the first type of standard was mainly used for telephone cables before the early 1980s), not for data transmission.

(2) Category II cable:

The highest frequency bandwidth of the cable is 1MHZ, which is used for voice transmission and data transmission with a maximum transmission rate of 4Mbps, which is common in old token networks using the 4Mbps standard token passing protocol.

(3) Category 3 cables:

Refers to the cable specified in the ANSI and EIA/TIA568 standards. The transmission frequency of this cable is 16MHz, and the maximum transmission rate is 10Mbps (10Mbit/s). It is mainly used for voice, 10Mbit/s Ethernet (10BASE-T) and 4Mbit/s token ring. The maximum segment length is 100m. It uses an RJ connector and has faded out of the market.

(4) Category 4 cables:

The transmission frequency of this type of cable is 20MHz, and it is used for voice transmission and data transmission with a maximum transmission rate of 16Mbps (referring to 16Mbit/s token ring). It is mainly used for token-based local area networks and 10BASE-T/100BASE-T. The maximum network segment length is 100m, and it uses RJ-type connectors, which are not widely used.

(5) Category 5 cables:

This type of cable has increased winding density and is covered with a high-quality insulating material. The maximum frequency bandwidth of the cable is 100MHz and the maximum transmission rate is 100Mbps. It is used for voice transmission and data transmission with a maximum transmission rate of 100Mbps. It is mainly used in 100BASE-T and 1000BASE-T networks. The maximum network segment length is 100m and uses RJ connectors. This is the most commonly used Ethernet cable. In a twisted pair cable, different pairs of wires have different lay lengths. Usually, the lay period of 4 pairs of twisted pairs is within 38.1mm in length, twisted in a counterclockwise direction, and the twist length of a pair of wires is within 12.7mm. As shown below:

Category 5 unshielded twisted pair cable has 4 winding pairs, but no anti-drawing.

(6) Category 5e cable:

Category 5e has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR) and signal-to-noise ratio (SNR), smaller delay error, and greatly improved performance. Category 5e cable is mainly used for Gigabit Ethernet (1000Mbps).

Category 5e cables use 4 winding pairs and one anti-drawing wire. The color of the wire pairs is exactly the same as that of the Category 5 cables.

(7) Category 6 cable:

The transmission frequency of this type of cable is 1MHz~250MHz. The Category 6 wiring system should have a large margin in the PS-ACR at 200MHz, and it provides twice the bandwidth of Category 5e. The transmission performance of Category 6 wiring is much higher than the Category 5e standard and is most suitable for applications with transmission rates higher than 1Gbps.

An important difference between Category 6 and Category 5e is that the performance in terms of crosstalk and return loss is improved. For the new generation of full-duplex high-speed network applications, excellent return loss performance is extremely important. The Category 6 standard cancels the basic link model, and the wiring standard adopts a star topology structure. The required wiring distance is: the length of the permanent link cannot exceed 90m, and the channel length cannot exceed 100m. As shown in the following figure:

Category 6 cables are somewhat different from Category 5 or Category 5e cables in appearance and structure. They not only have an insulating cross frame, but also place the four pairs of twisted pairs in the four grooves of the cross frame. The cable diameter is also thicker. The cross frame in the center of the cable rotates as the length changes, and the four pairs of wires are stuck in the grooves of the frame, maintaining the position of the four twisted pairs, improving the cable's balance characteristics and crosstalk attenuation.

(8) Category 6A or Category 6A:

The transmission frequency is 500MHz, twice that of Category 6 cable, and the maximum transmission speed can reach 10Gbps. It is mainly used in 10 Gigabit networks. Category 6a cable is an improved version of Category 6 cable. It is also an unshielded twisted pair cable specified in ANSI/EIA/TIA-568B.2 and ISO Category 6/Class E standards. It has great improvements in crosstalk, attenuation and signal-to-noise ratio. As shown below:

(9) Category 7 cables:

Category 7 cable is an 8-core shielded cable. Each pair has a shield layer (usually a metal foil shield DINTEK), and then there is another shield layer outside the 8 cores (usually a metal braided mesh shield DINTEK). The interface is the same as the current RJ-45. As shown below:

The transmission frequency can reach at least 600 MHz and the transmission rate can reach 10 Gbps. It is mainly designed to adapt to the application and development of 10 Gigabit Ethernet technology. This cable is the latest shielded twisted pair cable in the ISO Category 7/Class F standard. In addition, the connector type of Category 7 cable is also different from other types of network cables, which is GigaGate45 (CG45).

The larger the type number, the newer the version, the more advanced the technology, the wider the bandwidth, and of course the more expensive the price.

3. Classification by shielding or not

Depending on whether there is a shielding layer, twisted pair cables are divided into shielded twisted pair (STP) and unshielded twisted pair (UTP).

(1) Shielded twisted pair cable

Shielded twisted pair cables have a metal shielding layer between the twisted pair and the outer insulating jacket. Shielded twisted pair cables are divided into STP and FTP (Foil Twisted-Pair). STP means that each line has its own shielding layer, while FTP only works when the entire cable has a shielding device and both ends are properly grounded. Therefore, the entire system is required to be a shielded device, including cables, information points, crystal heads and distribution frames, and the building needs to have a good grounding system. The shielding layer can reduce radiation, prevent information from being eavesdropped, and prevent the entry of external electromagnetic interference, so that the shielded twisted pair cable has a higher transmission rate than similar unshielded twisted pair cables.

(2) Unshielded twisted pair cable

Unshielded Twisted Pair (UTP) is a data transmission line consisting of four pairs of transmission wires of different colors. It is widely used in Ethernet and telephone lines.

Unshielded twisted pair cable has the following advantages:

• No shielding jacket, small diameter, saving space and low cost;
• Lightweight, easy to bend and install;
• Minimize or eliminate crosstalk;
• Flame retardant;
• It is independent and flexible and suitable for structured cabling.

Therefore, unshielded twisted pair cables are widely used in integrated wiring systems.

4. Transmission distance of network cable

The transmission rate of network cables is strongly related to various conditions such as network topology and network equipment. In actual use, low-specification network cables can also be used at high rates in short distances. For example, CAT5e can indeed reach 10Gbps in short distances and short times, but this cannot be guaranteed. The following table summarizes the transmission distances and rates of various network cables with reference to the IEEE802.3 standard. It is recommended that you use the following table as a standard for pre-sales consultation and actual selection: