作为线缆行业从业者，相信大家非常熟悉以太网络线缆，比如说超五类网线、六类网线和七类网线等等,但是您知道Cat8 八类网线是什么吗？它与之前的各类版本有何差异，今天大家一起来扒扒它与Cat5、Cat6、Cat7网线的区别.

八类网线是什么？【Category 8】

Category 8 was ratified by the TR43 working group under ANSI/TIA 568-C.2-1. It is defined up 2000 MHz and only for distances from 30 to 36m depending on the patch cords used. ISO is expected to ratify the equivalent in 2018 but will have 2 options:

Class I channel (Category 8.1 cable): minimum cable design U/FTP or F/UTP, fully backward compatible and interoperable with Class E_A (Category 6_A) using 8P8C connectors
Class II channel (Category 8.2 cable): F/FTP or S/FTP minimum, interoperable with Class F_A (Category 7_A) using TERA or GG45 connectors.

Category 8 is designed only for data centers where distances between switches and servers are short. It is not intended for general office cabling.

八类网线是最新一代双屏蔽（SFTP）的网络跳线，它拥有两个导线对，可支持2000MHz的带宽，且传输速率高达40Gb/s，但它最大传输距离仅有30m，故一般用于短距离数据中心的服务器、交换机、配线架以及其他设备的连接.

Cat8 八类网线的标准

Cat8 八类网线的相关标准由美国通信工业协会(TIA )TR-43委员会于2016年正式发布，具体如下：

1．符合IEEE 802.3bq 25G / 40GBASE-T标准，规定了Cat8 八类网线的最小传输速率，可支持25 Gbps和40 Gbps的网络布线

2．符合ANSI / TIA-568-C.2-1标准，规定了Cat8 八类网线的通道和永久链路，并包含电阻不平衡、TCL和ELTCTL的限制

3．符合ANSI / TIA-1152-A标准，规定了Cat8 八类网线现场测试仪测量和精度要求

4．符合ISO / IEC-11801标准，规定了I/II 类Cat8 八类网线的通道和永久链路.

三种结构

八类网线第一种结构：每对屏蔽+铝箔总屏蔽+外被

八类网线第二种结构：每对屏蔽+编织总屏蔽+外被

八类网线第三种结构：每对屏蔽+铝箔总屏蔽+编织总屏蔽+外被

八类与Cat5、Cat6、Cat7网线的区别

Classes and categories

The standard defines several link/channel classes and cabling categories of twisted-pair copper interconnects, which differ in the maximum frequency for which a certain channel performance is required:

Class A: link/channel up to 100 kHz using Category 1 cable/connectors
Class B: link/channel up to 1 MHz using Category 2 cable/connectors
Class C: link/channel up to 16 MHz using Category 3 cable/connectors
Class D: link/channel up to 100 MHz using Category 5e cable/connectors
Class E: link/channel up to 250 MHz using Category 6 cable/connectors
Class E_A: link/channel up to 500 MHz using Category 6_A cable/connectors (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)
Class F: link/channel up to 600 MHz using Category 7 cable/connectors
Class F_A: link/channel up to 1000 MHz using Category 7_A cable/connectors (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.)
Class I: link/channel up to 2000 MHz using Category 8.1 cable/connectors (specification under development)
Class II: link/channel up to 2000 MHz using Category 8.2 cable/connectors (specification under development)

The standard link impedance is 100 Ω (The older 1995 version of the standard also permitted 120 Ω and 150 Ω in Classes A−C, but this was removed from the 2002 edition).

The standard defines several classes of optical fiber interconnect:

OM1: Multimode fiber type 62.5 µm core; minimum modal bandwidth of 200 MHz·km at 850 nm
OM2: Multimode fiber type 50 µm core; minimum modal bandwidth of 500 MHz·km at 850 nm
OM3: Multimode fiber type 50 µm core; minimum modal bandwidth of 2000 MHz·km at 850 nm
OM4: Multimode fiber type 50 µm core; minimum modal bandwidth of 4700 MHz·km at 850 nm
OM5: Multimode fiber type 50 µm core; minimum modal bandwidth of 4700 MHz·km at 850 nm and 2470 MHz·km at 953 nm
OS1: Single-mode fiber type 1 dB/km attenuation at 1310 and 1550 nm
OS1a: Single-mode fiber type 1 dB/km attenuation at 1310, 1383, and 1550 nm
OS2: Single-mode fiber type 0.4 dB/km attenuation at 1310, 1383, and 1550 nm