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. 

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.

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 CablesOnDemand.com.

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:

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 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 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]