Network Know How

What is the difference between regular Cat 5e and Cat 5e 350MHz?

2009-12-08T10:45:00.003-06:00

Contrary to popular opinion and cable marketing hype, a MHz rating is not a measure of speed. When cable is tested, a series of signals are sent from one end of the cable to the other. At the other end, a receiver measures the signal strength and integrity to make sure that the cable meets its standard, in this case the Cat 5e standard. The MHz rating is just the range of frequency used to test the cable. The Cat 5e standard calls for testing over a frequency range of 100MHz.

Both regular Cat 5e and Cat 5e 350 MHz are suitable for gigabit networks.

Theoretically if one could utilize a greater range of frequency for transmission, one could send more data across the cable and improve speed. However, at this point in time, almost all computers and networking equipment only have the ability to transmit across a range of 100 MHz, so the hold up is the electronic equipment, not the cable. Plus, just because a box of Cat 5e cable hasn't been tested to 350MHz (or 400MHz or 600MHz or what have you) doesn't mean that it isn't capable of carrying a signal across this range.

When people call FOURPAIR.com and ask whether they should buy regular Cat 5e or the more expensive Cat 5e 350MHz, we recommend the regular. When you pay for a higher MHz rating, you're basically paying for extra testing. That testing may or may not be worth the extra cost to you. It may be worth it if future-proofing is a major concern that will keep you awake at night, but you have a tight budget to work with at the same time. If future-proofing is your number one concern and your budget is looser, skip the high MHz Cat 5e and go for the Cat 6 which is significantly different from Cat 5e cable.

Cable Buyers Beware of Low Grade Cable

2009-04-09T10:31:00.028-05:00

When you go out and purchase cable to install in your home, whether it is Coax Cable, LAN Cable, etc., you should always make sure you are getting what you pay for. Like everything else in life, when you are buying cable and you come across a deal that sounds too good to be true, then it probably is.

I have been in the business of selling telecommunications cable and components for years. And every year it seems that more and more low priced substandard cable is flooding the market. This is a rapidly growing problem as it effects many people. It personally effects my business because I only sell high quality cable that is UL Listed, but I have to face competitors that are buying cheaply made cable and passing it off as the best thing since sliced bread. Some of these manufacturers are even putting UL labels on this low grade cable even though it is not UL verified.

This cheap cable is making its way into many homes and buildings across our nation. The good news is that a few people are getting the results they want from this cable and I say more power to them for saving some money and getting the desired result. On the other hand, there are many other not so lucky people that are having to rip out this inferior cable and pay additional money for quality cable and installation because there network was too slow or just didn't work. There is nothing worse than paying for something twice, so be diligent when you are purchasing your cable and make sure that you are getting quality cable with verifiable UL or ETL certifications. Also, if your installer is providing the materials for the job then you better make sure that he/she is diligent in this process as well.

You may be asking yourself, "How can there be so much bad cable on the market especially with UL labels on them"? Well this answer is simple. Many manufacturers will build quality cable: have it tested: get a legitimate UL number and then have some Chinese factory put that number on substandard cable to save costs. For instance, the compounds used to make plenum rated cable are much more expensive than those used in riser rated cable. So if you used riser materials and call it plenum you save tons of money and maybe someone dies as a result. One manufacturer offered to sell me the same "PLENUM" cable they are shipping to other suppliers. It consisted of insulating some pairs of the Cat 5e cable with plenum rated FEP and the other pairs with riser rated insulation. It would save me over 25% on our cost of PLENUM cable. I refused the offer, but I'm sure many sellers out there haven't or won't.

As I mentioned earlier, this problem has been growing and growing, and finally it is starting to come full circle. The Communication Cable & Connectivity Association (CCCA) are major players in the Telecommunications Cable Industry and they have begun the process of trying to clean up this mess. They are gathering information to try and weed out the dishonest and/or ignorant suppliers. The CCCA is a well funded and exclusive organization with plenty of clout with both testing agencies like UL as well as enforcement agencies like the Federal Trade Commission. So hopefully their efforts will stop this inferior cable from flooding our markets or at the very least slow it down.

So when you are in the market to purchase telecommunications cable be aware of the inferior cable that is out in the marketplace. The best thing to do to ensure that you are getting quality cable is to ask questions. Ask for a spec sheet and make sure all the specs meet or exceed the standards set for that type of cable. Ask the seller for the UL number on the cable (if it is UL Listed then the number will be printed on the cable, so don't buy cable that has no UL number), and then go to UL's website to verify this UL number. Another good thing that you can do is ask for the shipping weight of a cable and compare it to others.........I purchased two boxes of cable from a competitor because I beleived it was low grade cable due to the fact that they were selling it for so cheap. My suspicions were confirmed when the two boxes of the Cat 5e Riser Cable weighed the same amount as one box from my warehouse. Cat 5e standards call for bare copper conductors which is what I sell, but these guys were selling cable that had Copper Clad Aluminum conductors and they were still calling it Cat 5e which is a flat out lie. Aluminum is much cheaper and lighter than copper and not as good of a conductor. So these guys are using cheaper materials as well as saving money on shipping costs in & out because the cable weighed less. No wonder they could sell it so cheap. CABLE BUYER BEWARE!!!!

Should I consider using fiber optic cable?

2008-08-19T13:26:00.007-05:00

While I wouldn't recommend running Fiber Optic Cable to every port on a network because it is uneccesary and expensive, fiber does make an excellent backbone cable. It is also the perfect solution to connecting two locations that are over 100m (328ft) apart on the same network. Also, the bandwidth on fiber optic cable is much greater than it's copper counterparts (Cat 5e & Cat 6) and will help facilitate any future upgrades to your network.

To connect two copper (meaning Cat 5e or Cat 6) networks together with fiber to make one network, you'll need two fiber-fed switches or two media converters. A fiber-fed switch is the same as any other switch except that one of the ports accepts a fiber connector. A media converter simply converts electrical signals (which run over copper) to optical signals (which run over fiber) and vice versa.

If you already own quality switches that meet your needs, you'll probably want to go with the media converters. They'll allow you to use all of your existing equipment, otherwise you can just purchase a switch that has fiber fed ports. With either of these options you will have to fork over a little money, but the good news is that the prices on these items have dropped tremendously over the last couple of years.

Plenum cable is expensive, can't I just install the cheap stuff?

2008-08-19T10:22:00.004-05:00

Not all installations require plenum cable. But if the fire code requires plenum cable, the answer is NO. You must use plenum cable.

For some customers, being frugal is an act of personal discipline that can overcome even their basic fears of fire and agonizing death from inhaling poisonous smoke. They compare the prices of plenum cable with the prices of riser cable (or even residential general use cable), assume that their office buildings won't catch on fire, and demand that the "cheap stuff" be installed.

Any reputable installer knows that this is a terrible idea. The hard part is getting the customer to understand this.

The best policy is to be blunt and point to the pocketbook. If the cable is not up to code, the fire marshall or building inspector will require all of it to be removed. It doesn't matter if the entire staff was supposed to move into the new building tomorrow, it doesn't matter if the walls are already in place, and it doesn't matter if someone just spent $10,000 (or more) on the new network; all of the "cheap stuff" will have to go. Then one gets to pay for the cable that should have been used in the first place in addition to the "cheap stuff" that had to be ripped out and thrown away.

It is always more frugal to follow the building codes than to ignore them because if you don't then you may end up wasting lots of time and money by having an installation done twice.

What is a patch panel used for?

2008-05-22T10:37:00.003-05:00

This is a 24 port rack mount patch panel from FOURPAIR.com:

A patch panel separates the hardwiring of your network from your networking equipment. Each run of cable that goes throughout the house or building is punched down on the back of the patch panel. Here is what the punch down area on the back of a patch panel looks like:

Rather than RJ45 ports, this side is equipped with punch down terminations and color-coding for T568A and T568B wiring. There are also independent verification testing symbols for UL and 3P.

Each set of punch down terminations corresponds to a port on the front of the panel. Patch Cables connect the ports on the front of the patch panel (or panels) to your networking equipment (such as switches, hubs, and routers).

Some people get by without a patch panel by putting crimp-on connectors on the ends of their runs and plugging them directly into their networking equipment. This can be done when a budget is especially tight, but it's something to avoid if possible as it can result in a great deal of confusion and mess when you try to change anything in the future since it results in loose cables dangling out of the wall or ceiling.

What type of coax cable should I use for my television?

2008-04-07T20:52:00.001-05:00

First figure out what you're installing it for. If you're putting it in to run regular cable television (CATV) or master antenna television (MATV), you don't need coax with special sweep-testing. The signals from these types of inputs are very strong. If you're planning on using satellite television (SATV), however, you'll want to make sure that you use coax that has been sweep-tested to 3GHz as recommended by most satellite service providers.

In any of these cases, you want to use RG-6.

Then it comes down to the shielding. Coaxial cable has two types of shielding: a foil and a braid. A 40% braid is a loose braid and is the most economical. It is generally used in places like motels where getting perfect reception isn't terribly important because people will only be there for a night or two. A 60% braid is the standard braid for RG-6. Most professional installers use RG-6 with a 60% braid. Quadshield coaxial cable has two foils and two braids. RG-6 Quadshield is the premium choice for RG-6 and is used by most people who have the chance to choose the cable for their own systems.

The type of conductor in your coaxial cable will also be important. The two conductors you will find in coax are copper clad steel (CCS) or solid copper core (SCC). Copper clad steel will be suitable for most installations, but if you want the best signal possible, then you should look to purchase a cable that has a solid copper conductor. The stronger signal produced by a solid copper conductor is ideal when you are using a satellite signal or you are looking for the best signal for your HDTV. The copper clad steel conductor will work for both satellite and HDTV, but to make sure your signal is as strong as it could be, then use the solid copper conductor.

Another thing to look for is UL listing or ETL verification. This independent testing ensures that cable actually is what the seller or manufacturer claims that it is. There is a lot of bargain coax out there without any sort of independent testing mark, so you'll want to specifically ask about this before making a purchase.

What is the difference between CL2 and CL3?

2008-04-02T16:03:00.001-05:00

CL2 is the designation for Class 2 Circuit wire and CL3 is the designation for Class 3 Circuit wire. Both are regulated under NEC Article 725. They are both used for remote-control, signaling, and power-limited circuits. In plain English that means that CL2 and CL3 are types of multi-purpose wire used for things like security systems, speaker wire, intercom systems, nurse call buttons, and more.

The difference between the two is that CL2 is rated for up to 150 volts while CL3 is rated for up to 300 volts. (NEC 725.71 F) According to NEC 725.2, CL2 offers some protection from electric shock while CL3 offers a bit more because it is rated to carry more voltage.

CL3 may be used in place of CL2, but not the other way around.

What is Cat 6e or Cat 7?

2008-04-02T13:28:00.001-05:00

As far as TIA (Telecommunications Industry Association) standards go, Cat 6e and Cat 7 do not exist. Standards for Cat 6e or Cat 7 have not been approved by TIA; therefore, Cat 6 is currently the highest TIA standard for twisted-pair communications cable (As of 3/02/2008).

If you see cable called "Cat 7 or Cat 6e" (or some other higher number), that is just a name that a company made up to put on their cable. One manufacturer's Cat 6e or Cat 7 could be built by totally different standards and specifications than another manufacturer's cable.

So, if you still want to pay the extra bucks to get Cat 6e or Cat 7, just know that you will be getting cable that could be made anyway the manufacturer feels like it. To me, your best bet is to go with Cat 6 cable, this way you can rest easy knowing that your cable is up to standards.

What is plenum cable?

2008-04-02T13:10:00.001-05:00

"Plenum" is a fire code rating. It is sometimes identified by the designation "CMP" meaning a communications plenum rated cable.

Plenum cable has a jacket made of Teflon rather than PVC (which you will find on CM or CMR rated cable) and is used in spaces designated for air-handling, such as drop ceilings that conceal return air vents in office buildings. The Teflon gives off much less poisonous gas than PVC when it burns. Thus by using plenum cable in air-handling spaces one prevents poisonous gas from being created and spread throughout the building through the air ducts during a fire.

Many commercial installations require the use of plenum cable. To make certain you are installing cable that is up to code, you have to check with your local fire marshal or building inspector. The laws vary from state to state and town to town.

If you have a copy of the NEC (National Electrical Code) book, take a look at section 800.51 (A). This states that one test used to define CMP cable is the Standard Method of Test for Flame Travel and Smoke of Wire and Cables for Use in Air-Handling Spaces. You can also take a look at the UL July 2004 Cable Marking Guide (page 21 under CMP) to see the UL requirements for a CMP rating based on this test.

What is the difference between Cat 5e and Cat 6?

2008-04-01T16:33:00.001-05:00

This is one of the most common questions we're asked. There are two major differences:

Signal to noise ratio

Bandwidth used to test the cable

The first difference is the most important. Cat 6 Cat 6 is twelve times less "noisy", than Cat 5e. When your computer sends data across your network some data packets are lost or corrupted along the way. These packets have to be resent by the system. The better the signal to noise ratio is on your network, the less often this happens.

As computer networks become faster, the signal to noise ratio becomes more important. If the network is racking up packets that must be resent faster than it can resend them, the network may eventually fail or slow to a crawl with the backlog. Using cable and components that have better signal to noise ratios, such as those rated to Cat 6, can help to prevent this potential problem.

As for the testing bandwidth, the official Cat 5e standard calls for testing across a bandwidth of 100 MHz. The Cat 6 standard calls for testing across a bandwidth of 250 MHz. The reality is that most computers and networking equipment only transmit across a frequency range of 100 MHz. (In the future, of course, actual utilization of greater bandwidth may become more common.)

When it comes down to it, however, this particular stat isn't all that important. Many cable companies tout the high bandwidth of their cable. Some even test up to as high as 700 MHz. It sounds great for marketing, but the truth is that the MHz rating is not the same as speed. All cable rated Cat 5e or Cat 6 is capable of Gigabit Ethernet. The MHz rating is just the frequency range used for testing the cable.

What does AWG mean?

2005-03-18T14:45:00.000-06:00

AWG stands for American Wire Gauge, and it is a standard used for denoting wire conductor diameter. The system is counter-intuitive, so the lower the AWG, the thicker the conductor.

Actually the system is even more counter-intuitive than that. Once you get to wires thicker than 0 AWG, you do not use negative numbers. Instead you just add more zeroes and end up with wire sizes like 00000 AWG, or, written another way, 5/0 AWG.

If you pull a telephone or computer line out of the wall and snip off the end, chance are good that you'll be looking at conductors that are between 0.016 and 0.025 inches across which is 26 to 22 AWG. (That's 0.4039 to 0.6452 millimeters for the metric-ly inclined.) If you go home and rip a power line out of the wall for a snip--a very bad idea, you'll probably see conductors between 14 and 12 AWG.

The thicker the wire, the lower the AWG, and the lower the resistance per unit of length. For more information about load carrying capacity and the relationship of conductor diameter to AWG, visit Power Stream: Wire Gauge and Current Limits.

What UTP pairs do I use on a phone jack?

2005-03-17T14:13:00.001-06:00

There you are with a four pair wire, and a six conductor phone jack that has terminations for only three of the pairs. Which pair gets left out? It helps to look at a list of pair designations:

Pair 1: blue and white
Pair 2: orange and white
Pair 3: green and white
Pair 4: brown and white

If you're wiring only three pairs, you use the first three. If you're wiring only two pairs, you use the first two. That's easy enough. But sometimes things get more confusing and you have to terminate quad wire onto a Cat 3 jack or attach Cat 3 or Cat 5e cable to a telephony plate with quad wire screw terminals. In those cases you need to know how the quad wire conductors and Cat 3 or Cat 5e cable conductors match up so that you can translate between the coloring schemes. You may run into "quad wire" that has six conductors; the additional two conductors (blue and white) are included in the list below:

Red: blue conductor of the blue and white pair
Green: white conductor of the blue and white pair
Yellow: orange conductor of the orange and white pair
Black: white conductor of the orange and white pair
Blue: green conductor of the green and white pair
White: white conductor of the green and white pair

What does RJ-45 mean?

2005-03-16T15:08:00.001-06:00

Many people use the term "RJ-45's" to refer to Cat 5e jacks or Cat 5e plugs. This is not, however, always the case.

RJ-45 jacks and plugs have 8 pins. If you have a computer patch cable laying around, you can see them on the plug. (Those shiny metal lines on the end.) RJ-45's are sometimes referred to as 8P8C connectors. This stands for 8 Position (which describes the width) 8 Conductor (or 8 Connector depending on who you talk to).

There are many different types of RJ-45 jacks available including Cat 3, Cat 5e, Cat 6 and USOC (regular telephone). Usually your supplier will know which one you're asking for based on the type of wire you've purchased, but it doesn't hurt to check. Make sure that when you ask for RJ-45's, you get what you want by indicating the specification that you are trying to fulfill.

UPDATE: Thomas of TECHtionary 2.0 points out that some people may be curious as to what the "RJ" of RJ-45 stands for. It's short for "Registered Jack." Check out his site; it's definitely worth a look.

How far can I run Cat 5e or Cat 6?

2005-03-15T12:28:00.001-06:00

The standards for Cat 5e and Cat 6 call for a maximum run length of 90 meters or 295 feet. While you may make a longer run and get it to work, this is not recommended. Even if problems don't show up immediately, they may come up later as your computers are upgraded to transmit faster or your network is expanded. If you must make a longer run, you can either put a signal repeater in the middle of the line or you can make your long run with fiber optic cable.

If your run is between 295 and 590 feet, the repeater option may be the best option for you. A switch or hub will act as a repeater. Make sure that you locate it in such a way that both runs on either side of the repeater are within the 90 meter standard. It won't do much good to split a 500 foot run into two runs of 100 and 400 feet.

If your run is longer than 590 feet or if most of the run is outside, fiber optic may be your best option. You'll need a media converter or fiber fed switch at each end of the fiber run to convert your network signals back and forth between electrical signals on copper and light pulses on fiber. If you are running fiber optic cable underground, you'll need to protect the delicate glass fibers inside the jacket by running it through a conduit or by using armored fiber optic cable.

UPDATE: Here's some clarification on the 90 meter maximum run length. This is generally cited as the maximum horizontal run length. The max length from switch to node is 100 meters. This 100 meter length, however, includes the vertical drops and all passive links such as the patch cables from the switch to the patch panel and the patch cables from the jacks to the computers (or other types of nodes). Big thanks to Marc at Lockergnome for calling the need for this clarification to my attention.

UPDATE: I have deleted hubs as an option to be used as repeaters. A very helpful email from Steve Anderson of BIP Solutions explains:

Hi, just read the clarification, and thought I should mention that the run length includes hubs as well.

It's to do with the maximum distance between active nodes. Nodes with store and forward will extend the maximum distance.

The limit's imposed by the time it takes for the smallest packet to be entirely on the wire. If a packet is entirely on the wire, and the beginning hasn't been accepted by all other nodes in the same collision domain, then you could have one begin transmitting and corrupting the other packet. The real problem is the original node doesn't know this has happened, so will only retransmit it if requested.

What is a KVM switch?

2005-03-11T15:33:00.001-06:00

A KVM Switch is a keyboard, video, and mouse switch. It allows you to control more than one computer with the same keyboard, monitor, and mouse. Why would you want to do this?

A KVM switch comes in handy when you own and use more than one computer, but you don't want to cover your desk with or pay for a bunch of input devices. If you have an old computer that you'd like to access regularly, this is the perfect application for a KVM switch. Just set up the old PC near the new one, plug in your KVM switch, and both computers are accessible to you anytime. Some two port KVM switches even come with built-in cables.

KVM switches are a must in large network setups with several servers. No reason to take up space and go through the expense and hassle of setting up sixteen monitors and keyboards when you can just pick up sixteen port KVM switch. You can even get rack mountable configurations.

What type of wire should I use for my phone system?

2005-03-10T08:17:00.001-06:00

In the past people used quad wire, or POTS wire. This wire is not twisted, is susceptible to interference, and is not suitable for telephone systems with several lines. If you are updating an old system and you encounter this wire, your best option is to replace the old wire with some type of twisted pair wire, such as Cat 3 or Cat 5e, rather than expanding the system with the quad wire in place.

Most installers have been using Cat 3 for phones, but Cat 3 is getting harder to find, and the price difference between Cat 3 and Cat 5e has narrowed considerably to around five dollars per thousand feet. Cat 3 is still recommended for phones, but if there's any chance that your phone system may be used for data transmission in the future, an upgrade to Cat 5e would be well-advised.

Aside from future-proofing, there is another reason that some people use Cat 5e for phones: simplicity of installation. If you are wiring for a computer network at the same time that you are wiring for a telephone network and the job is very large, you may find it easier to contend with one type of cable rather than dozens of boxes of different kinds. There is truly nothing worse in an installation than pulling a long run, especially one that requires fishing through small conduits and around tight corners, only to find out that you pulled the wrong cable.

There are a few installers who use Cat 6 for telephone systems. Unless the phone network may be used as a computer network in the future, this is a strange choice. It is the equivalent of using a speed boat to cross a swimming pool or using a chainsaw to remove a small twig from a bush--it's very unecessary, very expensive, a big hassle for what you're trying to accomplish, but it will work.

Can I use Cat 6 cable with Cat 5e jacks and patch panels?

2005-03-09T09:13:00.001-06:00

For a system to be rated at Cat 6, all of the components in the system have to meet the Cat 6 standard. However, Cat 6 is fully backwards compatible with Cat 5e, so if the system's technical rating is of no concern to you, feel free to use all of the Cat 5e components you want.

Using Cat 6 cable with Cat 5e components is a great way to future proof your network if your budget is limited. Jacks and patch panels are relatively easy to switch out in the future if you leave enough slack in the cable that you can cut off the component ends and reterminate the runs. Cable is a bit tougher to change out once the walls are up.

What is a jack? How do I install one?

2005-03-08T13:02:00.001-06:00

Put as simply as is possible, jacks are the ports where you plug things in. Want to connect your computer to your Cat 5e network? You need a jack. Want to plug in the television and watch cable? You need a jack. Want to plug in your speakers to your new Dolby Digital 7.1 Surround Sound system? You need a jack.

Jacks look and connect differently depending on what they are for. Here is a picture of three keystone style jacks and a penny:

From left to right we have a Cat 5e jack, a Coax BNC jack, and a Cat 3 toolless jack.

In this picture, the port of each jack is facing the camera. The port is where you plug in your equipment and is the part of the jack that remains visible after the jack has been installed. The back side of the jack faces inside the wall. To better illustrate this, here is a picture of two jacks that have been installed in the FOURPAIR.com offices:

You can see how once the jack is snapped into the plate and the plate is attached to the wall, you can only see the port. You'll have to excuse the old school wall plate. (The much more attractive ones that we currently carry can be found in the wall plates section of FOURPAIR.com.) In case you're curious, that is a phone cord coming out of the yellow Cat 5e jack. In our offices, we use Cat 5e for our telephone system and Cat 6 for our computer network.

The back side of the jack is where the hardwiring in the walls is terminated. Watch for future blog posts explaining how to terminate many different types of jacks.