4 Questions to Determine Whether You’re Ready for an AEC Cable Solution

As new data centers are built and existing ones are redesigned and reconfigured, considerations for equipment, server placement and thermal performance are paramount. Even more critical, and likely more pressing, are the cable options that can have varying effects on up-line and down-line operations and performance. Simple changes between cable offerings can deliver better data quality, ease installation challenges and reduce thermal requirements. But understanding which cable makes the most sense—and when—is the first step in determining how to upgrade (or build) an efficient, scalable and reliable data center.

The world relies increasingly on data centers as cloud applications proliferate, and with so much on the line, consistent, reliable service is table stakes. That brings active electrical cables (AECs) to the forefront of the data center conversation. AECs join direct attach copper (DAC) cables and fiber optics. Designed to offer a clean signal for up to 7.0m, AECs are smaller than DACs—reducing the footprint required for cooling and making them easier to install. From budget to bandwidth, AECs offer a cabling option for evolving data centers that require upgrades without equipment replacement, enabling managers to add more server racks or even increase the total size of the data center with minimal disruption.

At the same time, DACs continue to play a vital role in today’s data centers. Questions surrounding channel length, loss budgets and means to minimize power consumption are important, and the answers are likely unique to each business. With so many factors driving final cabling decisions, what do you need to know as you research your data center options?

Passive Cables, Linear Amplifiers or Re-Timers?

Passive cables, such as DACs, contain minimal electronic components, use very little power and offer a cost advantage. They also deliver low latency, an increasingly valuable feature as we primarily operate—and need access to data—in real time. However, when used at longer lengths in an 800 Gbps/port environment at 112 Gbps PAM-4 (a brand of the pulse amplitude modulation technology), passive cables suffer from data loss issues, resulting in traditional 2+ meter 56 Gbps PAM-4 reaches being unachievable.

AECs solve the problem of data loss with re-timers—one placed at the beginning of the cable and one at the end. Re-timers recondition the data signal as it travels through the AEC on the way in and on the way out. An AEC’s re-timers create a cleaner signal, removing noise and amplifying the signal to yield cleaner, crisper data delivery.

Another type of cable that includes active electronic components, the active copper cable (ACC), offers linear amplifiers rather than re-timers. While a re-timer clears up or reduces noise within the cable, a linear amplifier does not. This means it does not recondition the signal but only amplifies it and, by doing so, also amplifies the noise. What’s the upshot? While linear amplifiers offer a lower-cost option, re-timers deliver a much cleaner signal. It really depends on the application, the desired performance and the budget.

Re-timers also offer a higher chance of success with plug-and-play scenarios. For example, if the top-of-rack (TOR) switch and the servers connected to it are made by different vendors, a cable with a linear amplifier may have difficulty maintaining acceptable signal integrity performance. It’s unlikely data center managers are interested in sourcing each equipment type from the same vendor or replacing existing equipment to create a single-vendor solution from top to bottom. Instead, most data centers mix and match equipment from various vendors, so successful “plug and play” of new servers into existing infrastructure with a guaranteed channel is simply more likely with re-timers. In this case, re-timers also represent a significant cost savings.

Channel Length in the World of 112G PAM-4—DACs or AECs? 

Passive DACs may be the right solution for a data center where cost and power are the most prominent issues and the DAC is servicing the length of the 112 Gbps PAM-4, 800 Gbps/port channel. However, for channels that are longer than 2.0m, passive DACs may not work.

AECs, on the other hand, offer an extended loss budget of up to 30 dB, and re-timers deliver superior signal integrity over lengths up to 7.0m between boxes (e.g., switch to server). Therefore, AECs provide a viable alternative for lengths above 1.5/2.0m at a lower cost than fiber optics.

How Do DACs and AECs Affect Thermal Issues?

AECs and DACs offer different solutions for different situations, but the budget constraints are always one of the biggest deciding factors. One large budget challenge is power consumption with the resulting heat dissipation required to cool the system.

DACS, being passive, use minimal power, so don’t add significantly to the heat generated in a data center. AECs are built with electronic components and, therefore, use power. However, while longer than DACs, AECs have smaller diameters, with conductors as small as 34 AWG. Less cable mass means less impedance, allowing more airflow, which can ease thermal issues. These are all important considerations to determine which cable is best to deploy in support of a given application.

What About Cable Management?

Cable raceways or trays often carry 25 to 50 large cable bundles connecting servers, meaning primary use of the relatively thick DAC cables makes them difficult to manage and adds significantly to space limitations.

AECs’ ability to reset loss and timing enables efficient signal transmission over smaller cable bundles. As a result, AECs offer lighter weight and a smaller bend radius compared to DACs, making routing easier and improving cable management.

As new data centers are built and existing ones are redesigned and reconfigured, considerations for equipment, server placement and thermal performance are paramount. Even more critical, and likely more pressing, are the cable options that can have varying effects on up-line and down-line operations and performance. Simple changes between cable offerings can deliver better data quality, ease installation challenges and reduce thermal requirements. But understanding which cable makes the most sense—and when—is the first step in determining how to upgrade (or build) an efficient, scalable and reliable data center.

The world relies increasingly on data centers as cloud applications proliferate, and with so much on the line, consistent, reliable service is table stakes. That brings active electrical cables (AECs) to the forefront of the data center conversation. AECs join direct attach copper (DAC) cables and fiber optics. Designed to offer a clean signal for up to 7.0m, AECs are smaller than DACs—reducing the footprint required for cooling and making them easier to install. From budget to bandwidth, AECs offer a cabling option for evolving data centers that require upgrades without equipment replacement, enabling managers to add more server racks or even increase the total size of the data center with minimal disruption.

At the same time, DACs continue to play a vital role in today’s data centers. Questions surrounding channel length, loss budgets and means to minimize power consumption are important, and the answers are likely unique to each business. With so many factors driving final cabling decisions, what do you need to know as you research your data center options?

Passive Cables, Linear Amplifiers or Re-Timers?

Passive cables, such as DACs, contain minimal electronic components, use very little power and offer a cost advantage. They also deliver low latency, an increasingly valuable feature as we primarily operate—and need access to data—in real time. However, when used at longer lengths in an 800 Gbps/port environment at 112 Gbps PAM-4 (a brand of the pulse amplitude modulation technology), passive cables suffer from data loss issues, resulting in traditional 2+ meter 56 Gbps PAM-4 reaches being unachievable.

AECs solve the problem of data loss with re-timers—one placed at the beginning of the cable and one at the end. Re-timers recondition the data signal as it travels through the AEC on the way in and on the way out. An AEC’s re-timers create a cleaner signal, removing noise and amplifying the signal to yield cleaner, crisper data delivery.

Another type of cable that includes active electronic components, the active copper cable (ACC), offers linear amplifiers rather than re-timers. While a re-timer clears up or reduces noise within the cable, a linear amplifier does not. This means it does not recondition the signal but only amplifies it and, by doing so, also amplifies the noise. What’s the upshot? While linear amplifiers offer a lower-cost option, re-timers deliver a much cleaner signal. It really depends on the application, the desired performance and the budget.

Re-timers also offer a higher chance of success with plug-and-play scenarios. For example, if the top-of-rack (TOR) switch and the servers connected to it are made by different vendors, a cable with a linear amplifier may have difficulty maintaining acceptable signal integrity performance. It’s unlikely data center managers are interested in sourcing each equipment type from the same vendor or replacing existing equipment to create a single-vendor solution from top to bottom. Instead, most data centers mix and match equipment from various vendors, so successful “plug and play” of new servers into existing infrastructure with a guaranteed channel is simply more likely with re-timers. In this case, re-timers also represent a significant cost savings.

Channel Length in the World of 112G PAM-4—DACs or AECs? 

Passive DACs may be the right solution for a data center where cost and power are the most prominent issues and the DAC is servicing the length of the 112 Gbps PAM-4, 800 Gbps/port channel. However, for channels that are longer than 2.0m, passive DACs may not work.

AECs, on the other hand, offer an extended loss budget of up to 30 dB, and re-timers deliver superior signal integrity over lengths up to 7.0m between boxes (e.g., switch to server). Therefore, AECs provide a viable alternative for lengths above 1.5/2.0m at a lower cost than fiber optics.

How Do DACs and AECs Affect Thermal Issues?

AECs and DACs offer different solutions for different situations, but the budget constraints are always one of the biggest deciding factors. One large budget challenge is power consumption with the resulting heat dissipation required to cool the system.

DACS, being passive, use minimal power, so don’t add significantly to the heat generated in a data center. AECs are built with electronic components and, therefore, use power. However, while longer than DACs, AECs have smaller diameters, with conductors as small as 34 AWG. Less cable mass means less impedance, allowing more airflow, which can ease thermal issues. These are all important considerations to determine which cable is best to deploy in support of a given application.

What About Cable Management?

Cable raceways or trays often carry 25 to 50 large cable bundles connecting servers, meaning primary use of the relatively thick DAC cables makes them difficult to manage and adds significantly to space limitations.

AECs’ ability to reset loss and timing enables efficient signal transmission over smaller cable bundles. As a result, AECs offer lighter weight and a smaller bend radius compared to DACs, making routing easier and improving cable management.

Comparing AECs and DACs: A Snapshot

Both AEC and DAC assemblies are vital for data centers to keep up with data demands with optimized efficiency and speed. Having a clear understanding of AECs’ and DACs’ unique capabilities helps data center managers decide which option is best for each unique situation and requirement.

By combining industry-leading expertise and manufacturing reliability, Molex cables deliver optimized data center routing and connectivity. Learn more about Molex’s AEC 112 Gbps PAM-4 Solutions and DAC Assemblies, along with our Turbo DAC Assemblies with zSFP+ Connectors by visiting our website.

Product Development Manager, Copper Solutions
I/O Solutions General Manager