The demands for high bandwidth keep increasing as the video and multimedia gain a large popularity among end users. The data rate of 1Gbps is gradually growing to 10Gbps. The Cat5e cables used to support 1Gbps network are no longer enough for 10Gbps, which calls for new specifications of twisted pair copper cabling. Ethernet cable with higher bandwidth such as Cat6 cable, Cat6a cable and Cat7 cables are introduced for high-speed applications of 10GBASE-T. Here comes some questions—What’s the difference between Cat6, Cat6a and Cat7? Cat6 vs Cat6a vs Cat7, which is better for 10GBASE-T network? This article can answer your questions.
Figure 1: 10GbE over Cat6 or Cat6a cables.
Cat6 (Class E), Cat6a (Class EA) and Cat7 (Class F) are improved twisted pair specifications that can support 10GBASE-T applications. Each cable is backward compatible, meaning you can plug a newer twisted pair cable into a device that is created for a slower cable. Cat6 can be used for 10Mbps, 100Mbps, 1000Mbps and 10Gbps. But Cat6 can support 10GBASE-T for only up to 55 meters (depending on crosstalk) and frequencies of up to 250 MHz. Cat6a (Cat6 augmented) is designed to support frequencies of up to 500 MHz, which is twice that of Cat6. And Cat6a can support up to 100 meters when transmitting 10Gbps. Cat6a cable can be divided into shielded and unshielded type respectively referred as F/UTP (shielded) and U/UTP (unshielded) cable. Cat6a F/UTP is easier to handle than Cat6a U/UTP. Cat7 cabling can also support 10GBASE-T but is rated for transmitting frequencies of up to 600 MHz.
Cat6 vs Cat6a: obviously 10GbE Cat6a cable has better network performance than 10GbE Cat6 cable. Cat6a 10GBASE-T cable using RJ45 connectors can deliver 10G performance of higher frequencies (500 MHz) and with longer link lengths (100 m) than that of Cat6 cable (250 MHz, 55 m). Compared with Cat6, Ca6a has more robust sheathing, which reduces alien crosstalk and improves signal-to-noise ratio.
While Cat6 10GBASE-T cable can support 10GBASE-T over distance between 37 and 55 meters depending on the alien crosstalk environment, there is no 10GBASE-T application support assurance over short runs of Cat6, because alien crosstalk is highly dependent on cable density. And the cable quality from different manufacturers can’t be guaranteed. Only when you test it will you know if the Cat6 cable meets the specification. Besides, adopting Cat6 cable in 10Gbps can’t make use of power-saving short reach mode. Short reach mode can reduce power consumption by 1W per port when using Cat6 of 30 meters or less. So 10GBASE-T cable Cat6 is not cost-effective and environment friendly for 10GBASE-T application. What’s more, Cat6 cable can’t dissipate heat as well as Cat6a 10GBASE-T cable since Cat6 10GBASE-T cable has smaller diameter conductor. Data center temperatures are increasing. At the same time, cable insertion loss also increases. This is not good for network performance.
Some people may argue that 10GbE Cat6 cabling is cheaper than 10GbE Cat6a cabling. But this cannot be guaranteed either. Say that if you gamble on running 10Gbps over Cat6 cabling, then you have to to replace all the Cat6 components when it does not work. This will cost much more than directly using Cat6a cabling. Unless you can install Cat6 cabling for 10GBASE-T according to the qualifications of ISO/IEC or TIA, you may predict decent performance with Cat6 up to 55 m.
In a word, 10GBASE-T cable Cat6 vs Cat6a, the former is not suggested to be used in 10GBASE-T applications because of various limitations. The minimum grade of cabling to be deployed in 10GBASE-T network should be Cat6a cable. As for which kind of Cat6a 10GBASE-T cable to use, you can read How to Choose the Right Category 6A Cable for Your 10G Networks for more detailed information.
Since in the discussion of Cat6 vs Cat6a, Cat6 is not recommended for 10GABSE-T cabling, then how about the newer twisted pair cable Cat7?
Actually Cat7 standard was ratified to support 10Gbps over 100 m earlier than Cat6a. A major advantage of Cat7 cable is that it has shield for each of the four wire pairs and for the four pairs as a whole. For this reason, Cat7 cable has greater noise resistance. But conversely, the shielding makes Cat7 less flexible and manageable. The key concerns are the wire pairs must be fully surrounded by shield in the cable from end to end, and must provide proper grounding.
Figure 2: 10GbE over Cat7 cables.
Also the connector type for Cat7 has small difference. Its worldwide standard is using RJ45 compatible GG45 connector. Though Cat7 can also use RJ45 connector, it will be less easier to terminate this cable with thick sheathing to the narrow jack in the field. You may need to hire a specialized electrician, or spend longer time to terminate the RJ45 jacks to Cat7 cables on your own.
In the laboratory Cat7 has shown the potential to transmit higher data rates of 40Gbps, 50Gbps and 100Gbps. But the Cat7 cable itself only provides the power and speeds of the equipment and Internet type it is working with. The Internet speed will not be improved when you only change to a faster cable but remain using a slower speed equipment. For example, if you’re using a 10GBASE-T copper switch to connect your 10G server, you will get 10G at most whether you replace Cat6a by Cat7 or not.
In terms of the price, for per 100ft 10GbE Cat7 Ethernet patch cable, it is about $10 more than 100ft 10GbE Cat6a Ethernet patch cable. And the price for 500ft Cat7 bulk cable is about the price for 1000ft Cat6a bulk cable, which is about $100 more. And usually we will need more than 2000ft bulk Ethernet cable for wiring an average house. Even if both of them can support 10GBASE-T for 100 meters, in the price point, using Cat7 will cost about $200 more. So if you want to save this budget or use the $200 somewhere else, you’d better choose Cat6a instead of Cat7.
Talking about Cat6a vs Cat7, as far as running 10GBASE-T, it is more cost-efficient and reasonable to choose Cat6a over Cat7 judging from many aspects.
You can use either twisted pair cable Cat6a or Cat6a or Cat7 for 10GBASE-T network. But from the comparisons of performance and other factors, it is not easy to conclude that when it comes to the question of running 10GBASE-T over Cat6 vs Cat6a vs Cat7, Cat6a is the most appropriate choice. 10GbE over Cat6 cable is limited within distances of 37 m to 55 m and is much dependent on the crosstalk. The quality of the Cat6 cable from different manufacturers also differs so the success can not be guaranteed. 10GbE over Cat7 cable is less easier to install, and is less flexible and manageable than Cat6a cable. The price for Cat7 cable is much expensive as well. So Cat6a F/UTP or Cat6a U/UTP is best for 10GBASE-T cabling.
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