What is Category 5, 5e, 6 and 7?

Category 5, 5 E, 6 and 7 Performance Specification Chart
ParameterCategory 5
and Class D

with additional
requirements TSB95
and FDAM 2
Category 5E
('568-A-5)

Category 6
Class E

(Performance at
250 MHz shown
in parentheses)
Proposed
Category 7
Class F

(Performance at
600 MHz shown
in parentheses)
Specified frequency rangeUp to 100 MHzUp to 150 MHzUp to 250 MHzUp to 700 MHz
Attenuation24 dB24 dB21.7 dB
(36 dB)
20.8 dB
(54.1 dB)
NEXT27.1 dB30.1 dB39.9 dB
(33.1 dB)
62.1 dB
(51 dB)
Power-sum NEXTN/A27.1 dB37.1 dB
(30.2 dB)
59.1 dB
(48 dB)
ACR3.1 dB6.1 dB18.2 dB
(-2.9 dB)
41.3 dB
(-3.1 dB)**
Power-sum ACRN/A3.1 dB15.4 dB
(-5.8 dB)
38.3 dB
(-6.1 dB)**
ELFEXT17 dB
(new requirement)
17.4 dB23.2 dB
(15.3 dB)
ffs**
Power-sum ELFEXT14.4 dB
(new requirement)
14.4 dB20.2 dB
(12.3 dB)
ffs**
Return loss8 dB*
(new requirement)
10 dB12 dB
(8 dB)
14.1 dB
(8.7 dB)
Propagation delay548 nsec548 nsec548 nsec
(546 nsec)
504 nsec
(501 nsec)
Delay skew50 nsec50 nsec50 nsec20 nsec
**Note: Requirements for Category 7 are currently under development.

Frequently Asked Questions

Q:
Are the cabling standards backward compatible to lower standards?
A: Yes, you can use a high grade category 6 cable for 10-megabit Ethernet, or voice (phone), for example.

Q: I have standard category 5 cable installed in my office. 1) Will I be able to upgrade to 100-megabits or higher? 2) Will it help to use Cat 5e patch cable?
A: If it was properly installed, upgrading to 100-megabits should not be a problem. Category 5 cable may be able to run Gigabit Ethernet, but Category 5E is recommended (for gigabit). As for the second part of the question, the answer is that it can only help, and it cannot hurt. The fact is that the weakest part of any category-5 link, are the patch cables used. I highly recommend the Custom Category 6 Patch Cables. 

Q: What is the difference between megabits, and megahertz?
A: When they refer to network speed, they specify it in megabits per second. This is the amount (or speed) in which the data is transferred. Megahertz refers to the analog frequency of the carrier signal that is used to transmit the data. One hertz, is completed when the carrier signal goes from zero, to it's positive peak, back to zero, to it's negative peak, and back to zero again. Category 5 cables are tested at 100 megahertz or higher. The higher megahertz frequencies can more easily reveal any defects in the cable or hardware. There is little relationship between the two. In theory, the higher the megahertz, the more megabits per second, you can transmit. 

Q: We have a 100-megabit Ethernet network, which is cabled with category-5 in our office. We need to get a group of computers onto the network that are located on the other side of our warehouse, about 600 feet away. I understand that category-5 cable is limited to a distance of 295 feet. What is the best way to accomplish this?
A: You can run a fiber optic cable and connect it to your existing hub with a Media Converter. Measure the exact distance of the cable run. Let us know the distance, and we will make a fiber optic cable for you, with connectors and a pulling eye, to protect the connections during installation. Now, use a 100 Base TX to FX Media converter on each end. On the far end, you could install a new Switch, off of the Media converter, and connect all of the users to the new hub.

Q: What is Cat 5 Plenum and PVC cable, and why is the Plenum cable so much more expensive?
A: Plenum rated cable has a Teflon coated jacket containing low smoke and low flame characteristics. Plenum cable is mandated to be installed in any "air handling" space. For example, most large office buildings use the ceiling to return air to the AC unit. This qualifies this ceiling as a Plenum ceiling, and all cable that goes through that ceiling, must be Plenum rated.

Q: Is the order of the colors really that critical in a patch cable? As long as both ends of a straight through cable match, won't the cable work well regardless of the color order?
A: Of course the signals that travel over those wire pairs are colorblind. That is to say that they could care less (if they could think) what color is on their insulation. However, the pairs are grouped inside of the cable and in the RJ-45 connector in a certain fashion. So each pair will react with each other in a unique way. This reaction does have an effect on the performance. The more important factor is the pairing. A circuit of either transmit and receive must travel over a pair that is twisted for maximum shielding from cross talk.

Q: I am planning a cabling installation in a large building. How can we keep all of the cable runs within the distance limitation of 100 meters?
A: Basically, you should strategically divide the building into sections and pick a central location (equipment closet) for each section, where all of the cable runs, in that area will fall within the 100 meters. Now choose a main equipment location. You now need to plan to run a "backbone" cable from the main equipment room, to each satellite closet. If the distance of a particular run is within 100 meters, you may run a category 5E backbone to that closet. If the run is over 100 meters, then run a fiber optic backbone cable for that closet. The backbone cable links the satellite hubs to the main network switch. Be sure to use "switch" ports, and not regular ports to link the hubs to the main switch, to assure that that segment will not have to share bandwidth with any other device.

PS: If only a few runs fall over the 100 meters, you may want to consider using media converters.
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