Category Archives: 10GbE CX4 Cables

10-Gigabit Ethernet Backbone Interface Options: Which One Should I Choose?

This week’s question comes to us from Chris in New York:
We plan to upgrade our network backbone to 10-Gigabit Ethernet.
What interconnect platform should we use? 



Thanks Chris for your question.  This topic comes up quite frequently for a number of reasons.  Not too long ago, only medium to large enterprises could viably afford to make the leap to 10-Gigabit Ethernet on their networks.  That is simply no longer the case today.  Not only are there hundreds of 10GbE-ready switch manufacturers on the market today, but there are also multiple interconnect platforms available that support the 10-Gigabit Ethernet protocol.  As you can see by the timeline above, 10-Gigabit Ethernet has already surpassed the point of being a widespread and mature technology; ensuring low implementation costs.

Because this is a lengthy topic, I will need to divide it up into two segments.  The first segment will focus on the most obvious interconnect platform for 10-Gigabit Ethernet applications: 10GBASE-T. 10GBASE-T, also referred to as IEEE 802.3an-2006, is essentially 10-Gigabit Ethernet over standard twisted pair (UTP or STP) copper wire, such as Category-6 (CAT6) Cables and Category-6a (CAT6a) Cables.  A great number of networks have featured a 1000BASE-T (Gigabit) backbone using CAT6/CAT6a. Transmitting data at 1.0 Gbps speeds over this cable type is fairly easy from a hardware perspective and was therefore a highly implemented option for network administrators.


 Pictured: Typical Gigabit Ethernet (1000BASE-T) Network 


However, the entire equation changes dramatically when you have to increase the data throughput by a factor of ten from 1.0 Gbps up to 10.0 Gbps.  At this high 10-Gigabit speed, a whole bunch of negative performance ramifications come into play that were simply ignored or non-existent in the case of Gigabit Ethernet.  Some of these factors include:

Bandwidth:  To transfer data at 10-Gigabit speeds, the required cabling must be designed to support a substantial amount of bandwidth.  To operate effectively over a sizable distance (up to 100 meters or 330 feet), Category-6a Cabling must be used thanks to its inherent support of up to 500 MHz of bandwidth.  To compare, regular Gigabit Ethernet (1000BASE-T) can operate with plenty of headroom using a 100 MHz bandwidth capable Category-5e (CAT5e) Patch Cable.  To increase bandwidth, you have to operate at extremely high frequencies.  High frequencies behave quite differently from lower frequencies, thus demanding a more capable interconnect design.

Bandwidth can be visualized as a pipe (see below).  A high-bandwidth capable interface, like 10-GbE, requires a thicker data pipeline (backbone) so that all of the high-speed data can stream through it without resistance. If you try and force high-bandwidth data through a low-bandwidth pipe, you will witness a massive slowdown in data throughput. Sometimes, like in real life, the pipe will burst and the interface will shut down.  This is why maintaining high bandwidth is so critical.    

(Pictured: Bandwidth Conceptualized via a Pipe) 


Alien Crosstalk:  Alien Crosstalk, also known as ANEXT, is when signals from outside sources, such as other patch cables in close proximity or other localized sources of electromagnetic interference (EMI/RFI) like lighting, power transformers, wireless access points, etc., interfere with the 10-Gigabit Ethernet signal that travels down the cable.  Regular Category-6 (CAT6) Cables do not address the issue of ANEXT directly and as a consequence can only support 10-Gigabit Ethernet at distances up to 50 meters (166 feet).

(Pictured: Cables Affected by Alien Cross-Talk)



To mitigate the problems associated with bandwidth and ANEXT, Category-6a Cables utilize three principles:  Pair Separation, Shielding and Tight Tolerance.  Pair separation involves placing a plastic x-shaped insulator in the middle of the cable itself.  This keeps a designated amount of spacing between the wire pairs, thus assisting with Near-End Cross-Talk (NEXT) and maintaining proper cable impedance.  Shielding involves shrouding the entire cable in a concentric ring of Aluminum foil.  This prevents outside EMI/RFI interference and related Alien Cross-Talk (ANEXT) from wrecking the signal.  Tight tolerance simply means that Category-6a (CAT6a) Cabling is designed and assembled with minimal tolerance for out-of-specification characteristics such as maintaining a perfect number of cable twists-per-inch. 

Now that the technical specifics are out of the way, how do we reach a determination as to whether 10GBASE-T (10-Gigabit Ethernet over Twisted Pair) is the right choice for your network upgrade?  I like to look at three critical cost factors.  The more dollar signs shown, the more expensive the cost.


Critical Factor #1:  Switch Cost 




In all likelihood, your largest upgrade expense is going to come from the cost of updating all of your switches to 10-Gigabit Ethernet compliant models.  Unfortunately, this is where 10GBASE-T fairs the absolute worst.  Development was significantly delayed on 10GBASE-T hardware, specifically the silicon chipsets that power the switches.  10GBASE-T proved far easier to develop on paper than it did in the real world.  As a consequence, while 10GBASE-T products are just barely trickling out to the market from a select few manufacturers, other 10-Gigabit Ethernet interface standards, such as SFP+ Direct Attach and 10GBASE-CX4 have taken hold.


Critical Factor #2:  Cable Cost




This is where the 10GBASE-T interface dominates hands-down.  Cables for 10GBASE-T are the absolute cheapest option because all you need to purchase are Category-6a (CAT6a) Patch Cables.  At Amphenol Cables on Demand (, we stock a variety of Category-6a (CAT6a) Patch Cords in your choice of length and color at prices starting at only $3.16 (even less when on sale).  This is perhaps 90-95% cheaper than the other aforementioned interface options!


Critical Factor #3:  Power Consumption




Power Consumption is the Achilles Heel of 10GBASE-T.  The fact is, the engineers who came up with the Ethernet standard decades ago never imagined that inexpensive twisted pair communications cable would support the blazing fast speeds of today.  As such, engineers have had to squeeze 10-pounds of bandwidth into a 1-pound bandwidth bag.  This comes at a price.  To make up for the cable’s inherent deficiencies, the switch has to do the heavy lifting by using extra power to sort through all of the signal errors and lost packets that will naturally occur over twisted pair cabling.  As such, 10GBASE-T switches are both power hungry and heavy in terms of heat dissipation, posing a major issue from an environmental management perspective.  There’s no such thing as a “Free Lunch” as they say; in this case the free lunch being cables that cost 90-95% less than other options!      



While 10GBASE-T, 10-Gigabit Ethernet over Twisted Pair, has been hyped for years as the inevitable de-facto solution for 10-Gigabit networks, reality simply eliminates this possibility.  Delayed development, cost overruns, limited suppliers; combined with high switch and power consumption costs makes 10GBASE-T an unattractive option. The only upside to 10-Gigabit Ethernet over CAT6/6a  is the fact that CAT6/6a Cables are so inexpensive.  I can’t in good conscience recommend 10GBASE-T for your network upgrade under these circumstances.  


Recommended?  NO


Stay tuned for the follow-up blog to this question in which we will discuss two other 10-Gigabit Ethernet interface choices: CX4 and SFP+.


The Cable Guy

Amphenol Cables on Demand


Questions About 10GbE CX4 Cables? Check Out the CX4 Cable FAQ!

10GbE-CX4 Cable Frequently Asked Questions

Network Engineers have a plethora of cabling options when it comes to installing a 10-Gigabit Ethernet compliant backbone, but which solution is truly optimal under the circumstances?  10-Gigabit Ethernet CX4, aka 10GbE-CX4 or 10GBASE-CX4, combines low cost, low latency, and low power consumption for the ultimate short-distance link.  Although CX4’s popularity has grown rapidly in recent years, there is still a great deal of confusion and misinformation regarding this technology.  Our exclusive Guide to CX4 Cables will help with all of your CX4 related questions.

Question 1:   What is CX4?


CX4, also known by its IEEE designation, 802.3ak, supports 10-Gigabit Ethernet data transfer over 4-lanes of copper cabling in each direction (8-lanes total).  In order to rapidly bring this technology to market, the IEEE workgroup designed CX4 to utilize field-proven InfiniBand type cabling and connectors.  Nearly one quarter of the world’s Top 500 super computers utilize InfiniBand interconnects for mission-critical applications, making it an ideal choice for CX4 use.  While InfiniBand is more proprietary in nature and requires licensing fees, CX4 is based on an Open Source MSA (Multi-Source-Agreement), allowing any manufacturer to develop CX4 products at significantly lower costs.

Question 2:   What is CX4 Used For?
CX4 is primarily used as a 10-Gigabit Ethernet interconnect for backbone applications.  With the rapid rise of Gigabit Ethernet at the desktop level (1000BASE-T), a broader data pipeline is required on the back-end to aggregate data between servers.  Therefore, it is not uncommon to see CX4 capable switches installed in nearly any environment, including data centers, enterprise networks, or even HD video distribution hubs. 


Question 3:   Are there any Limitations to CX4?

CX4 interconnects offer the advantages of low-cost, low-latency, and low-power consumption at the expense of range.  The length limitation for CX4 is 15m (49ft) when using passive cable assemblies.  Some novel solutions exist which use active signal boosters or fiber optics to achieve lengths beyond 15m, but these solutions negate the cost, latency, and power benefits inherent to CX4 technology.  Fortunately, lengths beyond 15m are rarely needed, since most switches reside in close proximity within a wiring closet.

Question 4:   What do I Need to Integrate CX4 into my Network?

Depending upon your particular requirements, several upgrade paths exist to integrate CX4 into your network.  Many switches from companies such as HP, Cisco, and Intel can be upgraded with a CX4 plug-in module.  These CX4 modules are available in XENPAK, X2, and XFP configurations.  Another option is to purchase a new CX4 capable switch.  These high performance switches often feature a combination of CX4 ports and standard RJ45 ports for Gigabit Ethernet.  Nearly all servers with PCI-Express slots can be upgraded with a CX4 enabled PCI-E NIC card.  Finally, you will need quality CX4 Cables to connect to your gear.

Question 5:   What Types of Connectors are used on CX4 Cables?

A properly designed CX4 cable should feature die-cast SFF-8470 InfiniBand type latching connectors.  These connectors are easy to engage and will maintain continuity even if significant strain or vibration exists along the body of the cable.  SFF-8470 thumbscrew style (i.e. SAS) connectors should be avoided since most equipment does not support them.  Amphenol CX4 cables utilize the best connector on the market today, the Fujitsu microGiGaCN™.  The microGiGaCN is the market’s original high-speed, differential-signal, copper interconnect for high-performance (data I/O) applications.

Question 6:   How Does CX4 Compare with 10GBase-R & 10GBase-T?

CX4 has numerous advantages over 10GBase-R (Fiber) and 10GBase-T (Cat-6).  An optical connection would require (2) 10-Gig optical modules and a fiber patch cord to function.  This has significant cost and power budget implications.  Running 10-Gigabit Ethernet over UTP cabling like Cat-6 may sound promising, but it is plagued by power consumption and latency issues.  Today’s 10GBase-T chipsets are power hogs, as they require several Watts just to separate out signal noise.  Here’s a comparison of how CX4 stacks up in terms of power-consumption in a 50-server datacenter.  Essentially, CX4 consumes 6x-20x less power. 

Power Comparison Chart

Question 7:   What is SpectraStrip SKEWCLEAR Cable?

SKEWCLEAR® is a proprietary shielded parallel pair wire technology designed and built by Amphenol SpectraStrip.  When transferring high-speed data over copper, signals will often arrive out of sync.  This problem, known as skew, can lead to the complete collapse of signal integrity.  SKEWCLEAR®,cable utilizes a novel manufacturing approach directed towards reducing within-pair and pair-to-pair time delay/amplitude-skew, critical for today’s high bandwidth applications.  All Amphenol CX4 cables feature SKEWCLEAR® wire.

Amphenol SpectraStrip SKEWCLEAR CX4 InfiniBand Cabling

Question 8:   Why Choose Amphenol Brand CX4 Cables?

As one of the world’s top three manufacturers of CX4 Cables, Amphenol is ready to meet the stringent demands of any potential 10-Gig network install, large or small.  Assembling 10-Gig capable interconnects is often more of an art than a science.  By using premium grade components and Amphenol-pioneered manufacturing techniques, Amphenol brand CX4 cables are simply the best cabling option on the market today.  Best yet, Amphenol brand CX4 cables are always in-stock and ready for same-day shipping at

Question 9:   Are Amphenol CX4 Cables Compatible with InfiniBand?

Absolutely.  Since CX4 cables share the same core architecture as InfiniBand cables, we took the liberty of dual qualifying our CX4 cables for both SDR and DDR InfiniBand.  Therefore, Amphenol CX4 cables will function as drop-in replacements for InfiniBand applications.  In addition to InfiniBand compatibility, Amphenol CX4 cables can be used in place of any competing CX4 cable from Gore, Tyco, Belkin, QLogic, HP, IBM, Cisco, and 3COM. Click below to download the Amphenol CX4 Cable Cross Reference Chart:

Amphenol 10GbE-CX4 Cable Cross Reference Chart


Question 10:   What If I Need Cables Longer than 15m (50ft)?

Well you’re in luck!  Cables on Demand has established a partnership with industry leader 3M and is now offering their extensive line of Active Optical InfiniBand/CX4 Cables in lengths up to 50m (164 ft), Also available are QSFP to CX4 Hybrid Active Optical Cables; allowing the linkage of newer 40G QSFP/QSFP+ equipment with legacy 10G CX4 platforms.  Check them out now at the following links:


CX4-CX4 Active Optical Cables CX4-CX4 Active Optical Cables
CX4 to CX4 Active Optical Cables from 3M™ Interconnect Solutions Now In-Stock! Available in lengths ranging from 10m (32.8′) to 30m (98.4′), 3M’s Active Optical Cables offer the best power consumption in their class and connect between hardware with SFF-8470 ports (CX4/DDR InfiniBand). Please click here to view our entire selection of CX4-CX4 Active Optical Cables.
QSFP-CX4 Active Optical Cables QSFP-CX4 Active Optical Cables
QSFP to CX4 Active Optical Cables [$50 OFF SALE] from 3M™ Interconnect Solutions Now In-Stock! Available in lengths ranging from 10m (32.8′) to 50m (164′), 3M’s Active Optical Cables offer the best power consumption in their class and help bridge the gap between gear with SFF-8436 ports (QSFP and QSFP+).and SFF-8470 ports (CX4/DDR InfiniBand). Please click here to view our entire selection of QSFP-CX4 Hybrid Active Optical Cables.

Have More Unanswered CX4 Cable Questions?  Ask the Cable Guy @ [email protected]