Q: What is the difference between cat 5, 5e, and 6 (plus proposed cat 7)?
A: See Chart Below
| Category 5, 5e, 6, and 7 Performance Specification Chart |
| Parameter | Category 5 and Class D
(with additional requirements TSB95 and FDAM2) | Category 5e
('568-A-5) | Category 6 and Class E
(performance at 250 MHz shown in parentheses) | Proposed Category 7 Class F
(Performance at 600 MHz shown in parentheses) |
| Specified Frequency Range | 1-100 MHz | 1-100 MHz | 1-250 MHz | 1-600 MHz |
| Attenuation | 24 dB | 24 dB | 21.7 dB
(36 dB) | 20.8 dB
(54.1 dB) |
| NEXT | 27.1 dB | 30.1 dB | 39.9 dB
(33.1 dB) | 62.1 dB
(51 dB) |
| Power-sum NEXT | N/A* | 27.1 dB | 37.1 dB
(30.2 dB) | 59.1dB
(48 dB) |
| ACR | 3.1 dB | 6.1 dB | 18.2 dB
(-2.9 dB) | 41.3 dB
(-3.1 dB)** |
| Power-sum ACR | N/A | 3.1 dB | 15.4 dB
(-5.8 dB) | 38.3 dB
(-6.1 dB)** |
| ELFEXT | 17 dB
(new requirement) | 17.4 dB | 23.2 dB
(15.3 dB) | ffs*** |
| Power-sum ELFEXT | 14.4 dB
(new requirement) | 14.4 dB | 20.2 dB
(12.3 dB) | ffs*** |
| Return Loss | 8 dB*
(new requirement) | 10 dB | 12 dB
(8 dB) | 14.1 dB
(8.7 dB) |
| Propagation Delay | 548 nsec | 548 nsec | 548 nsec
(546 nsec) | 504 nsec
(501 nsec) |
| Delay Skew | 50 nsec | 50 nsec | 50 nsec | 20 nsec |
Back to top
|
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.
Back to top
|
Q: How do they qualify Category 7, when the standard has not yet been written?
A: The various cable manufacturers have determined what the specifications will be, and are working with the standards committees to write the specifications.
Back to top
|
Q: What is the difference between megabits and megahertz?
A: When they refer to network speed, they quantify 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.
Back to top
|
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 a higher grade cat 5 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 5 E 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 suggest that every one who is responsible for a network should use the very best grade of patch cable available. I highly recommend the Custom Category 6 Patch Cables which are "state of the art".
Back to top
|
Q: I just bought some category 5E cable and jacks, plus a LAN-PRO-8 Toolkit from you guys, and want to install new cable runs, connecting them to an existing patch panel in our office. The patch panel is not marked 568A or 568B. How can I tell what it actually is?
A: Take a piece of cat 5E cable, about a foot or so. Connect a cat 5E jack on one end. Start with a 568B connection at the jack. Connect the other end to the patch panel in the standard fashion (blue, orange, green, brown). Now, test the cable from jack to patch panel with the LANTEST-PRO Cable Tester cable tester that was part of the toolkit. If it tests good, the patch panel is 568B, if not, reconnect the jack for 568A. Now retest. If it tests ok, it is 568A. Once you determine if it is A or B, you should wire all of the new jacks to that standard.
Back to top
|
Q: I am trying to troubleshoot a cat 5 jack that worked fine until recently, suddenly it doesn't seem to work. I disconnected the hub and the computer, and tested out the cat 5 line, and it tests ok. I took the computer to another cat 5 location, and it worked fine. What could be the problem?
|
| A: | Possible Cause | Test | Repair |
| 1 | Bad patch cable: hub side or user side | Test the line with the same patch cables attached. | If in doubt, change both patch cables. |
| 2 | Bad Hub port | Plug the line into a different hub port | If you find a bad hub port, block it off and use a different port |
If the above remedies do not help, then trace the line for it's entire length, looking for signs of, and correcting, any EMI interference, kinks, poor termination methods, tight cable ties, etc. Then, change the jack and patch panel port. If these methods do not work, you can call in a professional to do further testing, but it will most likely be quicker and less expensive just to re-install the line.
Back to top
|
Q: We have an 100 megabit Ethernet network, that 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 Media Converter. Measure the exact distance of the cable run. Let us know the distance, and we will make a fiberoptic 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 Hub, off of the Media converter, and connect all of the users to the new hub.
Back to top
|
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 special insulation that has 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. Please check with your building officials to see if you need plenum cable. The reason why it costs so much more, is because the material required for the insulation, must meet the standards for plenum cables while meeting the standards for category 5. This material is relatively expensive.
Back to top
|
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 color blind. 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 crosstalk.
Back to top
|
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 295 feet?
A: This question is may require an entire article to properly cover. Basically, you should strategically divide the building into sections and pick a hub location (equipment closet) for each section, where all of the cable runs, in that area will fall within the 295 feet. 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 295 feet, you may run a category 5E backbone to that closet. If the run is over 295 feet, 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.
Back to top
|
How to solve common USB cable questions:
| How To Question | Solution |
| How to connect a camcorder video output to USB | Use a USB-to-video or S-Video adapter |
| How to add USB ports to my MAC or PC | Add a USB controller card to your MAC or PC |
| How to netwrok computers with USB to share files and peripherals | Use a USB "SmartNet" cable |
| How to connect a device that is more than 16 feet from my hub | Use an "active" repeater extension cable |
| How to use a USB port to connect a network | Use a USB-to-Ethernet adapter |
| How to use a parallel port printer with USB | Use a USB-to-parallel (IEEE-1284) converter |
| How to connect a PS/2 mouse and keyboard to a USB port | Use a USB-to-PS/2 port converter |
| How to connect a serial device to USB | Use a USB-to-serial converter |
| How to share USB devices between computers | Use a USB switchbox - and don't forget your cables! |
Back to top
|
How to share devices or ports with switchboxes:
| Problem | Solution |
| How to share one monitor between two computers | If you have a PC with HD15 connectors, you can use a "manual" switchbox and two cables. |
| How to use two printers with one computer | Use a switchbox and cables to connect it to the printers. |
| How to share a printer between two computers without a network | Use a switchbox and cables to connect it to the computers. |
| How to share two printers between two computers | Use an auto switchbox, two normal printer cables, and two DB25 male-to-DB25 male cables. |
| How to switch between serial devices (digital camera) to share serial port | Use a switchbox and a cable. |
| How to use two computers with one keyboard, mouse, and monitor if your computer is an "AT" style | Use an auto switchbox, monitor cables, keyboard and mouse cables. |
| How to use two computers with one keyboard, mouse, and monitor if your computer is a "PS/2" style | Use an auto switchbox, monitor cables, keyboard and mouse cables. |
| How to use two keyboards, mice, and monitors with one computer | For an "AT" style computer, use an ASB-27001 switchbox, monitor cables, serial mouse cables, and keyboard cables. For a "PS/2" style computer, use adapters. |
Back to top
|
How to solve SCSI connection problems:
| Problem | Solution |
| How to add an external SCSI connector from my motherboard (controller card) 50-pin connector to my computer | Use a cable and an internal-to-external adapter |
| How to connect a "wide" (68-pin) drive to a "narrow" (50-pin) cable | Use an ADT-21107-01 |
| How to connect a "narrow" (50-pin) device to a "wide" (68-pin) cable | Use an ADT-6850-FF |
Back to top
|
How to solve Telecom/Datacom problems:
| Problem | Solution |
| How to connect two phone lines together | Use a TEC-34S "Modular in-line coupler." |
| How to split a phone line to run it to two different products | Use a TEC-29-64 "Modular duplex T-adapters." |
| How to connect two 10 Base-T cables together | Use a TEC-84KS "Modular in-line couplers." |
Back to top
|
|
