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26 E L EC TR I C AL CONNEC T I ON
AU T UMN 20 1 6
CATEGORY 8 QUESTIONS ANSWERED
A
s the Telecommunications
Industry Association (TIA)
TR-42.7 sub-committee
works diligently toward finalising the
specifications for Category 8 twisted-
pair cabling systems, we asked several
members of the subcommittee to answer
some questions about Cat 8.
Q: Can you provide a summary of how
a Cat 8 cabling system’s capabilities
compare to those of previous-generation
twisted-pair cabling systems, such as
Cat 6, 6A, 7, 7A, etc? (Please address
bandwidth, channel configuration
and channel distance, as well as other
performance characteristics you deem
appropriate. Please describe how, if at
all, the TIA is approaching backward
compatibility between Cat 8 and previous-
generation twisted-pair systems.)
Answer provided by Leviton Network
Solutions senior product manager
Mark Dearing:
Since Cat 5e was introduced in 1999, one
of the constants in structured cabling has
been the 100m, four-connector channel.
As data rates have increased, one of the
primary differences between category
systems is the frequency at which the
signal is transmitted over the cable.
Cat 7/7A offers a 100m four-connector
channel using shielded cabling and has
been designed to transmit signals at a
frequency of 1,000MHz. Even though Cat
7/7A operates at the higher frequency,
there is no corresponding improvement in
data rate over Cat 6A because 10GBase-T
is still the fastest twisted-pair-based data
rate recognised by IEEE 802.3. Therefore,
even if a Cat 7/7A cabling system is
installed, any available active equipment
would be limited to 10Gbps performance.
Cat 7/7A is not a recognised category by
TIA. (See Table 1.)
Cat 8 is a significant departure from
previous systems in that it uses a
frequency of 2,000MHz, and is limited to
a 30m two-connector channel. Unlike Cat
5e through Cat 6A, which could use either
unshielded twisted-pair (UTP) or shielded
cable construction, Cat 8 will require
shielded cabling. The most likely cable
construction for Cat 8 will be 22-AWG S/
FTP cabling.
Cat 8 is also unique in that the
International Organisation for
Standardisation (ISO) standard will
recognise two different classes of
product. (This topic is covered in greater
detail later in this article.) Class I is based
on the traditional RJ45 connector, while
Class II will accept non-RJ45 connectors
similar to Cat 7/7A. While both solutions
will offer backward compatibility in terms
of transmitting the lower category data
rates (1G or 10G), the Class I solution offers
a migration path using the RJ45 connector
platform. For example, a customer might
install a Cat 8 jack-to-jack link now, but
continue to use Cat 6A patch cords until
the active equipment is upgraded. While
the ISO standard includes both classes,
the TIA Cat 8 standard will only recognise
a Class I solution.
Q: Given Cat 8’s capabilities, where and
how is it most likely to be deployed (e.g.
in a data centre vs. a corporate LAN, top-
of-rack vs. end-of-row architectures)?
Answer provided by CommScope
engineering senior principal Masood
Shariff:
Cat 8 cabling is designed to support
AS INTEREST IN CATEGORY
8 CABLING APPLICATIONS
INCREASES,
PATRICK
MCLAUGHLIN
ASKS SUPPLIERS
FOR INSIGHT ON THE NEW
PROTOCOL.
CABLING
TABLE 1
Attribute
Category 5e Category 6 Category 6A Category 7/7A Category 8
Frequency 100MHz
250MHz
500MHz
1,000MHz
2,000MHz
Maxiumum
data rate
100Base-T 1,000Base-T 10GBase-T 10GBase-T
25GBase-T
40GBase-T
Distance
100m
100m
100m
100m
30m
Number of
connectors in
channel
4
4
4
4
2
Cable
construction
UTP or
Shielded
UTP or
Shielded
UTP or
Shielded
Shielded
Shielded
Connector
Type
RJ45
RJ45
RJ45
Non-RJ45
Class 1: RJ45
Class 2: Non RJ45
TABLE 2
ISO Cabling ISO (components)
TIA (cabling and components)
Class D
Category 5e
Category 5e
Class E
Category 6
Category 6
Class E
A
Category 6A
Category 6A
Class I
Category 8.1
Category 8
Class F
A
Category 7A
No equivalent
Class II
Category 8.2
Class II