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.

The Evolution Path of BASE-T

With the requirements laid on data center increasing rapidly, the ability to flexibly adapt to future demands is tremendously crucial for data center managers. Often this can be achieved by deploying higher bandwidth solutions in a part of the data center, provided that these systems are backwards compatible with existing infrastructure or it may be a cost-consuming method. BASE-T technology featured by its low cost, availability and flexibility is largely favored by data center designers. This article illustrates the migration of BASE-T technology so that people can future proof their data center tomorrow.

Why BASE-T Is so Popular?
To be short, three main advantages will be concluded in the following part.
1. Least cost access layer alternative when compared to other interconnect technologies

• Optical (e.g. SR, LR)
• Direct-Attached

2.Structured topology

• Common physical interface (RJ45)
• Flexibility and longevity
• Optimized for small to medium-sized data centers (< 20K square feet)

3. Supports auto-negotiation and Power-Over-Ethernet

• Simple plug and play installation
• Ubiquitous RJ45 interface simplifies 10GBASE-T to 40GBASE-T upgrade path

1000BASE-T—Gigabit Ethernet Over 4-pair Cat 5 Cabling
1000BASE-T (ratified in 1999) is a Gigabit Ethernet standard over copper wiring at the speed of 1000 Mbps. Each 1000BASE-T network segment can support a maximum length of 100 meters, and uses Category 5 cable or better (including Cat 5e and Cat 6). 1000BASE-T also uses a symbol rate of 125 Mbaud and all four pairs for the link and a more sophisticated five-level coding scheme. The 1000BASE-T SFP operates on standard Category 5 unshielded twisted-pair copper cabling of link lengths up to 100 m.

Realizing 10BASE-T
Upgraded from 1000BASE-T, 10GBASE-T (certificated in 2006) offers the most flexibility, the lowest cost media, and is backward-compatible with existing 1 GbE networks. 10GBASE-T connected with Cat 6 and Cat 6A (or above) cabling supports a length up to 100 meters that gives IT managers a far greater level of flexibility in connecting devices in the data center. 10GBASE-T and Category 6A cabling costs less than using either optical fiber or SFP+ direct attach copper (DAC) options that have been widely deployed to date center for 10 Gb/s. For example, EX-SFP-10GE-DAC-1M can only support a link length of 1m that largely limits its application. Figure 1 presents a comparison between 1000GBASE-T and 10GBASE-T.

Road to 40GBASE-T in Data Center Networks
If there is a 10GBASE-T for switch-to-server and switch-to-switch connectivity, there will be a 40GBASE-T over twisted pair cabling for the 40G data center deployment according to the IEEE. Twisted pair cabling with the RJ-45 connector has always been the first choice for IT professionals, based on its low cost and ease of use. Unlike fiber or twinax solutions, twisted pair cabling can automatically switch to different data rates, such as from 100MbE to 10GbE. Therefore migration to 40GBASE-T does not require a upgrade of all the equipment of the data center, which will reduce of the overall expenditure of the data center.

The advantages of 40GBASE-T are clear, but the path from initial ratification to commercial availability is not always smooth. There still a few months off for 40GBASE-T standardization, here comes some good news, as well as some considerations.

40GBASE-T is specified with transmission performance up to 2 GHz (four times the bandwidth of Category 6A) with a lot more stringent alien crosstalk requirements. Since initial 40GBASE-T applications would be limited to data centers, the traditional twisted pair Ethernet 100m link length is not essential. Additionally, Industry players helping in the development of an industry standard for 40GBASE-T have to ensure that it could be supported and rolled out cost-effectively. The new standard will minimize the time it will take to develop new electronics for switches and servers that can support 40GBASE-T connectivity, by building on the work already completed to support 10GbE connections. The standard will also support the ubiquitous RJ-45 connector. Sooner or later, 40GBASE-T will be upon us. Nowadays 40GBASE-LR4, 40GBASE-SR and 40G QSFP+ cables are there to help with the deployment of 40G connectivity. Take JG330A as an example, it is QSFP+ to 4SFP+ Passive Copper Cable available for short reach application. Figure 2 shows a data center twisted-pair migration roadmap.

Summary
BASE-T technology (1000BASE-T, 10GBASE-T or 40GBASE-T) always retains the traditional advantages—low cost, easy to deploy and auto-negotiation for plug and play and backwards compatibility. 1000BASE-T and 10GBASE-T have already brought benefits to people. But no one can foresee that 40GBASE-T will be used in the future but future-proof planning of the cabling is important, given the long life of the cabling systems. Fiberstore provides a full range of BASE-T products including 1000BASE-T SFP, 1000BASE-T media converter, 1000BASE-T GBIC transceiver, etc. And 40GBASE-T devices will be coming soon. If you have any request of our products, please send your inquiry to us.