SFP+ DAC Cables – HP JD097C and JD095C Illustration

SFP+ Direct Attach or SFP+ DAC, as the name implies, uses SFP+ MSA and the inexpensive copper twinax cable with SFP+ connectors on both sides, provides 10G Ethernet connectivity between devices with SFP+ interfaces, which make itself a cost-effective solution for 10G network application. But SFP+ Direct Attach has a limited link distance within 10 meter. thus the target application is interconnection of top-of-rack switches with application servers and storage devices in a rack. Many vendors offer 10G SFP+ Direct Attach cables, today’s article will first talk about two HP SFP+ DAC cables—JD097C and JD095C, then move on to the further illustration of the 10G SFP+ DAC cables.

HP JD097C and JD095C

They are both HP DAC cables, JD097C is HP 10G SFP+ passive Direct Attach copper twinax cable with a link length of 3m, and JD095C has the same specification with the JD097C but with a shorter link distance of 0.65m. Table 1 shows the models of HP 10G SFP+ DAC cables. For the detailed information about SFP+ DAC cables, please read on.

10 Gigabit Ethernet and Copper Cabling Choices

As switching standards mature and copper cabling standards catch up, the use of copper cabling for 10GbE is becoming more common. Currently, there are three different copper cabling technologies for 10 Gigabit Ethernet, each with different price and performance capabilities (see Table 2). Although fiber (SFP+ optics) delivers the lowest latency, many IT departments use copper cabling for switch-to-switch or switch-to-server Connections.

10GBase-CX4, published in 2004, was the first 10 Gigabit Ethernet copper standard. CX4 was relatively economical and allowed for very low latency. Its disadvantage was a too-large form factor for high density port counts in aggregation switches. SFP+ is the latest standard for optical transceivers. 10G SFP+Cu Direct Attach Cables (DAC) connect directly into an SFP+ housing. This new copper solution has become the connectivity of choice for servers and storage devices in a rack because of its low latency, small form factor, and reasonable cost. 10GBase-T or IEEE 802.3an-2006 was released in 2006 to run 10 Gigabit Ethernet over CAT6a and CAT7 copper cabling up to 100 meters. While promising, 10GBase-T still needs technology improvements to lower its cost, power consumption, and latency.

Direct Attach Cables are Convenient for Short Runs

10G SFP+ Direct Attach is a copper interconnect using a passive twinax cable assembly that connects directly into an SFP+ housing. It has a range of 10 meters and like 10GBASE-CX4, is low power, low cost and low latency with the added advantage of having the small form factor of SFP+, and smaller, more flexible cabling. Figure 3 shows the basic components of 10G network.

SFP+ Direct Attach cables integrate SFP+ compatible connectors with a copper cable into a low-latency, energy-efficient, and low-cost solution. DAC are available in several lengths up to 10 meters (33 ft) and are the currently the best cabling option for short 10 Gigabit Ethernet connections.

Top-of-Rack (ToR) switches use the SFP+ form factor to provide high port density 10 Gigabit Ethernet in an efficient 1U form factor. Server and network storage vendors use 10 Gigabit SFP+ network adapters on their equipment for the same reason. DAC simplify rack cabling and termination. Each server and network storage device can be directly connected to the ToR switch, eliminating the need for intermediate patch panels. DAC are flexible enough for vertical cabling management within the rack architecture. The only cabling outside the rack is the ToR switch uplink connection to the aggregation layer, making moving racks easy.

Conclusion

The SFP+ interfaces enables mass migration of the 1GbE network to 10GbE by offering a very low cost 10G SFP+ (direct attached copper cable assembly) option for short reach interconnects along with multimode and single-mode fiber options. The SFP+ interface accepts along with hot-pluggable, small-footprint, optical transceivers, a Direct Attach Cable, which replaces two optical modules and a connectorized optical fiber with a twinax copper cable assembly. Fiberstore offers third-party SFP+ DAC cables including the above HP JD097C and JD095C. These compatible SFP+ interfaces are tested in prior to shipping to ensure its high quality and compatibility. If you have any requirement of our products, please send your request to us.

10GBASE-T – Will It be the Best Media Options for 10G Data Center?

Ratified in 2006, 10GBASE-T is the standard to provide 10Gbqs connections over balanced twisted-pair copper, including Category 6A unshielded and shielded cabling. It provides great flexibility in network design due to its 100-meter reach capability. An immediate use for 10GBASE-T is to build the data center access-layer network that connects servers to access switches. But is it the best options for 10G data center? Understanding this requires an examination of the pros and cons of current 10GbE media options.

10GBASE-CX4
10GBASE-CX4 was the first favorite for 10GbE deployments, however its adoption was limited by the bulky and expensive cables, and its reach is limited to 15 meters. The large size of the CX4 connector prohibited higher switch densities required for large scale deployment. Larger diameter cables like 10GBASE-CX4 are purchased in fixed lengths resulting in challenges to manage cable slack. As a result, pathways and spaces may not be sufficient to handle this larger cable.

SFP+ 
SFP+’s support for both fiber optic cables and DAC which makes it a better solution than CX4. SFP+ is commonly used for 10G today, but it has limitations that will prevent itself from moving to every server. The following image shows a SFP+ nodule, SFP+ DAC cable and a 10GBASE-T SFP+ port media converter.

10GBASE-SR—10GBASE-SR (SFP+ fiber) fiber is great for its low latency and longer distance (up to 300 meters), but it is expensive. SFP+ fiber offers low power consumption, but the cost of laying fiber networking everywhere in the data center is prohibitive. The SFP+ fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is much more expensive. In addition, replacing a copper connection that is readily available in a server to fiber creates the need to purchase not only the fiber switch port, but also a fiber NIC for the server. EX-SFP-10GE-SR is compatible Juniper SFP+ transceiver that requires a OM3 cable to realize its 10G connectivity, which is an indispensable component for a 10G network.

10GBASE-SFP+ DAC—DAC is a lower cost alternative to fiber, but it can only reach 7 meters and it is not backward-compatible with existing GbE switches. Take MA-CBL-TA-1M as an example, it is designed to cover a distance of 1m for 10G connectivity. The DAC cables are much more expensive than structured copper channels, and cannot be field terminated. This makes DAC more expensive than 10GBASE-T. The adoption rate of DAC will be low since it does not have the flexibility and reach of 10GBASE-T.

10GBASE-T
The major benefit of 10GBASE-T is that it offers the most flexibility, the lowest cost media, and is backward-compatible with existing 1GbE networks. Like all BASE-T implementations, 10GBASE-T covers a lengths up to 100 meters, which gives network designers a far greater level of flexibility in connecting devices in the data center and the most flexibility in server placement since it will work with existing structured cabling systems. For higher grade cabling plants (category 6A and above), 10GBASE-T operates in low power mode on channels under 30 m. This means a further power savings per port over the longer 100m mode. And because 10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in existing 1GbE switch infrastructures in data centers that are cabled with CAT6 and CAT6A (or above) cabling, enabling network designers to keep costs down while offering an easy migration path to 10GbE.

One challenge with 10GBASE-T is that the early physical layer interface chips (PHYs) consumed too much power for widespread adoption. But there comes a good news with 10GBASE-T is that the PHYs benefit greatly from the latest manufacturing processes. The newer process technologies will reduce both the power and cost of the latest 10GBASE-T PHYs. The latest 10GBASE-T adapters require only 10 W per port. Further improvements will reduce power even more. In 2011, power dropped below 6 W per port, making 10GBASE-T suitable for motherboard integration and high-density switches.

Conclusion
Of all the media options offered above, 10GBASE-T breaks through important cost and power consumption barriers in 10GbE deployment as well as its backwards compatibility with 1GbE networks. Deployment on 10GBASE-T will simplify data center infrastructures, making it easier to manage server connectivity while delivering the bandwidth needed for heavily virtualized servers and I/O-intensive applications. I must say, 10GBASE-T will be the best option for 10GbE data center cabling in the near future.