Monthly Archives: May 2014

40GBASE-CR4 QSFP+ Direct Attach Cable

The 40GBASE-CR4 short reach copper segment is defined in Clause 85 with the standard. It specifies a media system according to four lanes of PCS data carried over four twinaxial cables. A twinaxial cable is just like coaxial cable, with the exception that each twinaxial cable has two inner conductors instead of the single conductor seen in coaxial cable.

The 40GBASE-CR4 standard defines a medium dependent interface that’s using a quad small form-factor pluggable (QSFP+) connector, referenced within the IEEE standard as small form-factor specification SFF-8436. The QSFP+ module isn’t standardized with a formal standards group, but instead is specified by a multisource agreement (MSA) produced by competing manufacturers.

As technology advances, cabling and equipment vendors work together to develop smaller and more efficient connectors and modules.While the segment length is specified up to 7 m, some vendors provide both active and passive versions with the 40GBASE-CR4 cable, using the active versions capable of longer segment lengths. As an example, a vendor offer lengths of 1, 3, and 5 m in passive cables, with 7 and 15 m supported in active cables. You’ll find variations in supported cable types and lengths among different vendors, and it’s up to you to verify the sup? ported cable lengths on the equipment you purchase.

The QSFP+ connector module used on the copper cables is exactly the same basic module as that used on 40Gb/s optical fibre links. However, instead of providing an optical transceiver at each end to which a fibre optic cable is connected, the 40GBASE-CR4 cable uses the QSFP+ module but leaves out the expensive optical lasers.

A fixed-length 40GBASE-CR4 direct attach cable segment, that is always sold with the QSFP+ modules permanently attached to each end of the cable. This cable provides four pairs of conductors in a fairly thick cable, with an outer di? ameter which range from 6.1 mm (0.24 inches) for a 1 m cable up to 9.8 mm (0.39 inches) for a 7 m cable length. The bend radius is typically specified as being 10 times the outer diameter. That might lead to a bend radius of from 6.1 cm (2.4 inches) to 9.8 cm (3.85 inches) for the cable outer diameters mentioned.

The QSFP+ module itself is roughly three inches in length, not including the plastic tab that, when pulled, disengages the connector from the port. This will make for a fairly long connector assembly on either side of the cable, and to connect anything besides closely associated equipment, you’ve got to be capable to route the cable and the permanently attached QSFP+ modules through any intervening cable management trays and cable guides.

Although QSFP+ transceiver module has 38 contacts on it, the 40GBASE-CR4 standard only specifies the set of contacts needed for transmitting and receiving four lanes of data. The signal crossover from source lane (Tx) to destination lane (Rx) is supplied from the wiring scheme specified by the standard.

Fiberstore offers 40G QSFP+ cables in various lengths and other options ,these cables can be used a direct replacement for OEM cables (e.g., Cisco etc.). These carrier-grade cables are utilized in tier-1 service providers, data centres, hospitals, universities, and enterprises across The United States.

SFP+ Direct Attach Cable Wiki

Today, 10G SFP+ direct attach cable (DAC) becomes cloud computing and cloud storage mainstream primary connection tool, but what is a direct attach cable? For this, different manufacturers of DAC cable have different presentations and descriptions. And here, we’ve got a number of related information together, mainly to discuss what exactly SFP + direct attach cable is and its other details, as well as discuss the advantages and disadvantages between active and passive SFP + DAC cable.

What Is 10G SFP+ Direct Attach Cable (DAC)?

The 10G SFP+ direct attach cable option is defined for 10G applications over copper cable. The 10G SFP+ DAC link utilises a receive equalizer from the host PHY/SerDes to be able to compensate for the Inter Symbol Interference (ISI) introduced by the cable. Electrical and mechanical specifications for SFP+ optical modules, 10G SFP+ direct attach cable, and hosts are defined in the SFF-8431 specification developed by the SFF Committee, with broad industry participation.

10G SFP+ direct attach cable is made from the inexpensive copper twinaxial cable with SFP+ connectors on both sides based on SFP+ MSA (multi-source agreement). It uses SFP+ connectors for 10G links instead of utilising an optical transceiver on each and every end as well as a length of fibre optic cable. It takes away the expensive optical lasers along with other electronic components. For both active and passive 10G SFP+ DAC cables, a smaller electrical component is used to recognize the SFP+ module and cable type to the Ethernet interface. 10G SFP+ direct attach cable is known as the successor technology to 10GBASE-CX4. It has the advantages of low power, low cost, low latency with the more benefits of having the small form factor of SFP+, and thinner, more flexible cabling compared with 10G SFP+ transceivers. Due to the distance limitation, the target application of 10G SFP+ DAC is interconnection of top-of-rack switches with application servers and storage devices in a rack.

10G SFP+ direct attach cable

Passive and Active 10G SFP+ Direct Attach Cable (DAC)

Vendors provide both active and passive versions of the 10GSFP+ direct attach cable. 10GSFP+ SFP+ DAC assembly is recognized as active in case there are signal processing electronics in the SFP+ module to increase signal quality and supply a longer cable distance. So the active direct attach cable can make it a possibility to support longer and thinner cable assemblies. The lower priced approach is the passive direct attach cable, which has a tendency to be shorter. Active 10G SFP+ DAC has a 10m distance limitation and passive 10G SFP+ DAC ranges from 1 m to 7 m. But you may discover variations in supported cable lengths among different vendors.

Passive 10G SFP+ direct attach cable is much less costly but require the host to do the work of driving it properly.

Benefits:

  • Lower Costs
  • Higher Reliability

Tradeoffs:

  • No LOS
  • No TX Disable
  • No Interrupts
  • Limited Management Interface
  • Host must drive Cu cable

Active 10G SFP+ direct attach cable provides 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:

  • More Expensive
Summary

This low-cost 10G SFP+ DAC is beneficial, as an example, for interconnecting a collection of switches, as well as for short-distance connections between switch ports and Ethernet interfaces on servers as well as other devices. Before the growth and development of 10GBASE-T, it was the only real low-cost copper connection designed for 10 Gbps operation. For active and passive 10G SFP+ DAC, each has advantages and disadvantages. You can select according to your special needs. You can also get 10G SFP+ direct attach cable of various compatible brands from here.

Related Article:  10GBASE-LRM vs. 10GBASE-LX4, Which One Wins?

Customised 40G QSFP+ to 8 LC AOC Breakout Cable

QSFP+ breakout cable is a cost-effective solution for short connection in 40G data centre. As one of QSFP+ breakout cables, 40G QSFP+ to 8 LC AOC (Active Optical Cable) is a high performance, long reach interconnect solution supporting 40G Ethernet, low power consumption, Fibre Channel and PCIe. It is compliant with the IEEE P802.3ba 40GBASE-SR4 and QSFP MSA.

40G QSFP+ to 8 LC AOC Specifications

40G QSFP+ to 8 LC AOC offers IT professionals a cost-effective interconnect solution for merging 40G QSFP and 10G SFP+ enabled host adapters, switches and servers. It is a high data rate parallel active optical cable (AOC), to overcome the bandwidth limitation of traditional copper cable. The AOC offers 4 independent data transmission channels and 4 data receiving channels via the multimode ribbon fibres. Each capable is capable of transmitting data at rates up to 10Gb/s, providing an aggregated rate of 40Gb/s. QSFP+ Breakout Cables are suitable for short distances and offer a highly cost-effective way to connect within racks and across adjacent racks. These breakout cables connect to a 40G QSFP+ port of a switch on one end and to four 10G SFP+ transceivers of a switch on the other end. Consequently, an aggregate data rate of 40Gbps over 100 metres transmission can be achieved by this product, to support the ultra-fast computing data exchange.  40g qsfp+ to 8 lc aoc breakout cable

All of FS 40G QSFP to 8 LC AOC are 100% compatible with major brands like Cisco, HP, Juniper, Enterasys, Extreme, H3C and so on. If you would like to order high quality compatible 40GBASE QSFP to 8xLC AOC and get worldwide delivery, you are suggested to come here. FS 40G QSFP to 8xLC AOC opens EEPROM for customer re-coding for different applications.

QSFP-8LC-AOC-1-xx Specifications

  • Length: 1 Metre
  • Connector 1: QSFP+
  • Connector 2: 8x LC Connector
  • Cable Type: AOC Cable
  • Full duplex 4 channel 850nm parallel active optical cable
  • Transmission data rate up to 10.3Gbit/s per channel
  • SFF-8436 QSFP+ compliant housing and hot pluggable electrical interface.
  • Management Interface and digital diagnostic monitoring(DDM) through I2C
  • Support Rx output pre-emphasis
  • 4ch 850nm VCSEL array
  • 4ch PIN photo detector array
  • Helix type multi-mode optical fibre cable of up to 100m
  • OFNP (Optical Fibre Non-Conductive Plenum) rated cable
  • Differential AC-coupled high speed data interface
  • Housing isolated from connector ground
  • Operating Temperature: 0 to 70℃
  • RoHS 6 compliant
  • 3.3V power supply voltage

QSFP-8LC-AOC-1-xx Applications

  • Infiniband transmission at 4ch SDR(2.5Gbit/s), DDR(5Gbit/s) and QDR(10Gbit/s)
  • Multi-channel 10Gb Ethernet transmission up to 4 channels
  • Fibre Channel transmission at 8.5Gbit/s per channel, up to 4 channels
  • QSFP+ to LC cables with MT connectors for plugging into existing cable runs or patch panels
  • Creating a breakout cable with four Duplex LC connectors for port expander applications
  • SDR / DDR / QDR
  • Data Centres
FS.COM Custom Service for 40G QSFP+ to 8 LC AOC

FS.COM provide 40G QSFP + to 8 LC AOC cable of which QSFP+ ports consumes less than 1.5W).  Our custom service for 40G QSFP+ to 8 LC AOC includes:

  • cable length—from 1 to 100m;
  • compatible brands—Arista, Brocade,Cisco, Dell, HP, etc.
  • Cable color—Aqua, Orange

If you are interested, you can customise your personal 40G QSFP + to 8 LC AOC cable from here.

Related article: QSFP+ Breakout Cables

QSFP+ to 4xSFP+ AOC and QSFP+ MTP Breakout Cable Solution

DWDM play an important role in submarine systems

Advantages of DWDM Multiplexer

DWDM is a very effective means of sharing transmission costs when fibre and other common components, such as optical amplifiers, dominate the overall system cost. The aggregate capacity of a single optical fibre can be increased by either increasing the bit rate or by increasing the number of wavelength channels using DWDM. The former requires development of new high-speed electronics, while DWDM allows fibre and fibre amplfier costs to be shared among all channels, driving down the total system cost per channel. Since information must still be coded onto the wavelength channels, today’s long-haul systems combine time-division multiplexing(TDM) with DWDM, taking advantage of high speed TDM advances to further reduce the system cost per bit per channel.
Fiberstore DWDM TECHNOLOGY

Both long-haul and undersea systems depend heavily on dense wavelength division multiplexed (DWDM) signals to achieve high-capacity transport.

Current long-haul system development efforts have focused on wide-band DWDM and ultra-long transport. These systems are enabled by new modulation formats, wideband amplification, wideband dispersion compensation and the use of forward error correction coding. Taken as a whole , these systems will deliver the lowest cost per transmitted bit over the longest distance . Optical fibre is an integral component of the entire system. T he fibre’s parametres have a significant impact on both cost and performance and influence the choice of most other components, such as amplifiers and compensators. In fact ,the use of wideband DWDM over ultra-long distances has elevated the fibre requirements in terms of dispersion management, nonlinear performance, distributed gain, spectral loss, and polarization mode dispersion (PMD).

History:

The first applications of fibre optic communication were to carry aggregated voice traffic between major metropolitan areas, such as the trunk lines from Washington, DC to Boston. In the United States, typical distances between major switch centres are on the order of 1600 km, while in Europe, these distances are typically 400 km. However, with the advent of all-optical or photonic switching located at these centres, the transmission distances without electronic regeneration could reach well into the thousands of kilometres in both cases, with the application space for these systems spilling over into the metro and regional networks. Such ultra-long distances have historically been reserved for point-to-point undersea fibre systems where transoceanic distances are typically 10,000 km and 4000 km for Trans-Pacific and Trans- Atlantic routes, respectively. As these distances are approached in terrestrial applications, it is not unreasonable to think of using similar system solutions for land applications.