What is SFP+ Direct Attach Copper Cable?

What’s SFP+ DAC twinax?
 
The SFP+ interface offers the highest density, lowest cost, and lowest power 10 Gigabit Ethernetsolution commercially available today. Further SFP+ enables mass migration of the 1GbE network to10 GbE by offering a very low cost 10GSFP+Cu (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 “10GSFP+Cu”, which replaces two optical modules and a connectorized optical fiber with a twinaxial copper cable assembly. The 10GSFP+Cu option is defined for 10GbE applications over passive copper with a reach of 8.5m. The 10GSFP+Cu link utilizes a receive equalizer in the host PHY/SerDes in order to compensate for the Inter Symbol Interference (ISI) introduced by the cable. Electrical and mechanical specifications for SFP+ optical modules, 10GSFP+Cu, and hosts are defined in the SFF-8431 specification developed by the SFF Committee, with broad industry participation.
 
What is SFP+ Direct Attach Copper Cable? 
10GSFP+Cu (SFP+ Direct Attach) is a copper interconnect using a passive twin-ax 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.
 
SFP+ Direct Attach is known as the successor technology to 10GBASE-CX4. SFP+ Direct Attach, as implied in the name, uses SFP+ MSA and by using the inexpensive copper twinaxial cable with SFP+ connectors on both sides, provides 10 Gigabit Ethernet connectivity between devices with SFP+ interfaces. SFP+ Direct Attach has a 10 meter distance limitation, thus the target application is interconnection of top-of-rack switches with application servers and storage devices in a rack.
 
Pasive and  Active SFP+ DAC Cables？ 
Passive cables are much less expensive but require the host to do the work of driving it properly.
Benefits:
• Lower Costs
• Higher Reliability
 Fewer Components (No Active Tx /Rx Components)
 Only Capacitors, Resistors, EEPROM, Cable
 
Tradeoffs:
• No LOS
• No TX Disable
• No Interrupts
• Limited Management Interface
• Host must drive Cu cable
 
Active cables offer the added benefit of being "optical-module" like.
 
Benefits:
• Enhanced Signal Integrity
• Longer Cable Lengths
• Transmit Pre-emphasis
• Active/Adaptive Receive Equalization
• Tx Disable
• Loss of Signal (LOS)
• Interrupts
• Management Interface
• Looks like an optical module
• Don’t have to worry about host Tx/Rx for Cu cables
 
Tradeoffs:
• Higher Cost
 
How does SFP+ Direct Attach Copper compare with 10GBASE-T?
10GBASE-T will work with Cat 6 and Cat 7 cables that are commonly used for 1Gb network connections and also support much longer distances than SFP+ Direct Attach Copper. 10GBASE-T is currently not supported for OneConnect adapters due to power requirements and high latency of 10GBASE-T PHY chips. 10GBASE-T PHY technology continues to evolve and could be suitable for adapter products by the end of 2010.

评论

发表评论

此博客中的热门博文

Common Armored Fiber Optic Cables

  Armored fiber optic cables are often installed in a network for added mechanical protection, as they have extra reinforcing in the cable housing to prevent damage. Two types of armored fiber optic cables exist: interlocking and corrugated. Interlocking armor is an aluminum armor that is helically wrapped around the cable and found in indoor and indoor/outdoor cables. It offers ruggedness and superior crush resistance. Corrugated armor is a coated steel tape folded around the cable longitudinally. It is found in outdoor cables and offers extra mechanical and rodent protection.   The Structure of an Armored Fiber Optic Cable In basic armored fiber cable designs, the outer sleeve provides protection against wind, solvents, and abrasion. This outer sleeve is usually made of plastic such as polyethylene. The next layer between the sleeve and the inner jacket is an armoring layer of materials that are difficult to cut, chew, or bu
阅读全文

what the Differences Between FBT Splitter and PLC Splitter

  In FTTx and PON architectures, optical splitter plays an increasingly significant role to create a variety of point-to-multipoint fiber optic networks. But do you know what is a fiber optic splitter? In fact, a fiber optic splitter is a passive optical device that can split or separate an incident light beam into two or more light beams. Basically, there are two types of fiber splitter classified by their working principle: fused biconical taper splitter (FBT splitter) and planar lightwave circuit splitter (PLC splitter). You may have one question: what’s the difference between them and shall we use FBT or PLC splitter?   What Is FBT Splitter? FBT splitter is based on a traditional technology to weld several fiber together from side of the fiber. Fibers are aligned by heating for a specific location and length. Because the fused fibers are very fragile, they are protected by a glass tube made of epoxy and silica powder. And then a stainless steel tube covers the inner glass tu
阅读全文

Introduction of Optical Fiber Couplers and How Do They Work?

 What are optical fiber couplers? A fiber optic coupler can be defined as an optical component used with one or more input fibers and several output fibers in fiber optic systems. A coupler essentially puts two or more cores of fibers together to connect. The simple coupler is the fused fiber 2x2 coupler. Couplers are used as multiplexers that are resistant to certain wavelengths. A fiber output depends on the wavelength of light and the frequency of polarization. The fiber refractive index also plays a significant role in the performance. Let’s checkout how do optic couplers work to understand this better. How do fiber optic couplers work? Either fiber optic couplers separate optical signals into multiple paths or combine multiple signals in one direction. Optical signals are more complicated than electrical signals, making it more difficult to design optical couplers than their electrical copy. Unlike electrical currents, the optical signal consists of a stream of signal carriers, in
阅读全文