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Get to Know Category 8 Cabling

Stéphane Bourgeois

Is Category 8 meant mainly for 40G? Get answers about the need for Cat 8 connector types. Here we explain the basics of Category 8 cabling and what it has to offer.

What are the main characteristics of Category 8? How will it affect data center infrastructure?

Category 8 cabling and components are specified with transmission performance of up to 2 GHz (four times the bandwidth of Category 6A cabling) with more stringent alien crosstalk requirements. Meeting these requirements requires a shielded cabling system (F/UTP, S/FTP or F/FTP).


The maximum reach for 25GBASE-T/40GBASE-T is 30 meters, which will be sufficient for most switch-to-server connections for top-of-rack (ToR), middle-of-row (MoR) or end-of-row (EoR) topologies.


Is Category 8 meant mainly for 40G?

Today it is intended primarily for 25G and 40G applications for short distances (up to 30 meters) for switch-to-server connections in a data center.


Will we need new connector types for Category 8?

Category 8 connectors use the 8-pin modular (RJ45) connector, and are fully backward compatible with previous categories. The transmission performance of a Category 8 mated plug-jack connection is specified and performs well up to a frequency of 2 GHz. To compare, Category 6A is specified to 500 MHz.


There is also an ISO Category 8.2 (Class II system) under development. It’s based on the Category 7A system specified in ISO 11801 2nd edition. Various connectors may be used for a Class II system; it is not clear whether a choice will be made to select a single connector. Backward compatibility with RJ45 is not assured, and would most likely require a hybrid patch cord.


Will Category 8 cables require more power?

No, because 25GBASE-T/40GBASE-T equipment is designed to operate over shorter distances up to a maximum of 30 meters. The power needed to transmit a signal 30 meters at 40 Gb/s is approximately the same as the power needed for 10GBASE-T transmission for distances up to 100 meters. Low power is one of the key objectives of the IEEE 802.3bq taskforce developing the 25GBASE-T/40GBASE-T standard.


When will the Category 8 standard be ratified?

It is under development in the TIA TR42.7 Subcommittee, and will be published as TIA-568-C.2-1 by mid-2016. The timeframe to publish the IEEE 25GBASE-T/40GBASE-T standards is also 2016.


Stay tuned for more information about Category 8 cabling on our blog in January. We’ll be sharing information about how Category 8 compares to its predecessor versions.


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