LC Connectors for High Density Data Centers

SC duplex connector was popular a few years ago. But as time goes on, smaller and more compact cabling components are required since the packing density of optical devices keeps increasing, namely high density. The smaller the shape, the more popular the component, just like development history of cellphone. Driven by this requirement, optic manufacturers start to produce mini components. The most widely known is the LC connector, a small form factor connector. The following article will introduce various types of LC connectors in details.

Common LC Connector

LC small form factor connector has just 1.25mm ferrule, half the size of the standard connector (compared with SC connector). Because of the high density design, LC connector solution can reduce the space needed on racks, enclosures and panels by approximately 50% throughout the network. So LC connector is a good solution for high density data centers. The LC connector uses RJ45 push-pull style plug that offers a reassuring, audible click when engaged. It makes moves, adds and changes easy and saves costs for you. Besides, the protective cap completely covers the connector end, which prevents ferrule end face from contamination and impact and enhances the network performance.

lc-lc-duplex

LC Uniboot

LC uniboot connector includes a finger latch release that there is no need for tools when making the polarity change. Some LC uniboot connectors are color-coded and labeled “A” and “B” to provide visual references when making a polarity change. The uniboot design is compatible with transceivers using the LC interface. The LC uniboot patch cords use special round cable that allows duplex transmission within a single cable, and it greatly reduces cable congestion in racks and cabinets comparing to standard patch cords. LC uniboot patch cord is perfect for high density applications. FS.COM LC uniboot patch cords are available in SM, OM3 or OM4 multimode fiber types to meet a wide variety of configurations and requirements.

uniboot-lc

Push-Pull LC Connector

If you have tried to release LC connectors in patch panels with high density, you must know how difficult it is. As to high density panel, thumbs and forefingers can not easily access to pull the connector. So some manufacturers start to offer a special LC connector which can be easily dealt with. And that’s push-pull tab LC connector.

Push-Pull-Tab-Patch-Cable

LC push-pull connectors offer the easiest solution for installation and removal. The special design is available in a compact model, ideal for minimizing oversized panels. With this kind of connector, you don’t need to leave additional space at the top or bottom to allow room for engaging the latch. The structure of the LC push-pull compact is designed as the latch can be slid back, instead of being pushed down, to facilitate smooth removal. It’s simple for installation and removal. Push-Pull LC patch cable allows users accessibility in tight areas when deploying LC patch fields in high density data centers. Push-Pull LC fiber patch cords are available in OM4, OM3 or single-mode fiber types to meet the demands of Gigabit Ethernet, 10 Gigabit Ethernet and high speed Fibre Channel.

Secure Keyed LC Connector

Secure keyed LC connectors are designed for network security and stability. 12 colors are available in FS.COM, including red, magenta, pink, yellow, orange, turquoise, brown, olive, etc. Connections only work when the color matches. The color-coded keying options provide design flexibility and facilitate network administration. It reduces risks and increases the security of network from incorrect patching of circuits. Secure keyed LC connectors feature low insertion loss, excellent durability.

lc-keyed

Conclusion

This article tells different types LC connectors, including common LC connector, LC uniboot, push-pull LC and secure keyed LC connector. The design of those LC connectors keeps improving to adapt to high density data centers. Nowadays, the trend of network is high speed and high density. So effective cable management is significantly important. And the key concern is how to manage more cables within less space. Thus, among so many kinds of interfaces, LC connector is the most frequently used and the most effective solution for space saving in data centers.

Originally published at http://www.fiber-optic-equipment.com

The New 10G Multimode Optical Solution – 10GBASE-LRM

10 Gigabit Ethernet has been applied for a long time in data centers and enterprise LANs. For 10G Ethernet connection, there are both single-mode and multimode solutions. First let’s see the original multimode solutions and supportable distances for 10G Ethernet.

10G-multimode solution-supportable-distance

10GBASE-S operates at 850nm wavelength. It can support up to 300m distance over laser-optimized OM3. This makes it a popular standard for data centers and cooperate backbones. For the conventional OM1 and OM2 which are not optimized for laser transmission, the furthest supportable distance is 33 m and 82 m. So these two solutions are only used in equipment rooms or small data centers.

10GBASE-LX4 was specified to support 300 m over three cable types. So it relies on coarse wavelength division multiplexing (CWDM) which is more complex and expensive technology. 10GBASE-LX4 operates at 1300nm wavelength and that requires additional cost on mode-conditioning patch cords (MCPCs).

The high cost and relatively slow adoption of 10GBASE-LX4 drive the development of a new standard—10GBASE-LRM. 10GBASE-LRM is developed to offer a longer reach for conventional fiber cables at a lower cost and smaller size than 10GBASE-LX4. The following will talk about 10GBASE-LRM from three sides.

Transmission Distance

On condition the supporting distance, 10GBASE-LRM can only support 220 m. It’s suitable for LAN networks within buildings. But a cabling survey provides that for 10G network, the distance is not able to address 30% of in-building channels.

Electronic Dispersion Compensation

The key to the long reach of 10GBASE-LRM on conventional multimode fiber is electronic dispersion compensation (EDC). EDC is deployed as an integrated circuit that acts like a complex filter on the received signal from the optical fiber. The purpose is to extend the maximum supportable distance. 10GBASE-LRM applies EDC technology and is therefore independent of the optical wavelength. 10GBASE-LRM operates at 1300 nm.

EDC chips is added to a linear detector in the receiver. As an additional component, it increases cost, consumes power and wastes heat. It can only work as intended in conjunction with a linear detector and amplifier. Because the EDC device must operate on a faithful analog rendition of the optical waveform in the fiber. For 10GBASE-LRM, to reproduce the optical waveform with precision, extra requirements and cost on the receiver design are needed.

Multiple Transmit Launch Conditions

In order to improve the chances of operating at a higher bandwidth, 10GBASE-LRM relies on multiple transmit launch conditions.

One launch is achieved by using mode-conditioning patch cord. The other launch is produced using a regular multimode patch cord. Through the two launches, different modes can be achieved and a favorable operating condition can be easily found.

There are four possible patch cord combinations at both ends of the channel. The preferred launch uses MCPCs on both ends. This process requires a test for link stability for each configuration. The user should shake and bend the patch cord at the transmit end while observing channel health indicators at the receive end. The shaking and bending of the cords causes changes to the received waveform which the receiver must tolerate in normal operation. If there were transmission errors, then users should change another launch. The errors indicate that the channel is operating near or beyond the limit of the receiver’s capability and the link may fail in operation.

launch-conditions-for-10gbase-lrm

However, the 10GBASE-LRM standard’s committee refuse to implement this channel test. So the burden of the shaking and bending lies on the users. It’s not good for the popularity of 10GBASE-LRM.

Comparison of Several 10G Transceivers Cost

The following will compare the cost of 10G transceivers from several sides, including laser, receiver, package and cords.

Laser: 10GBASE-LRM uses 1310nm fabry perot lasers, which cost fewer than 10GBASE-L’s and 10GBASE-LX4 DFB lasers, but more than 10GBASE-S’s 850nm VCSELs. 10GBASE-LRM requires tighter transmitter waveform control to limit the transmit waveform dispersion penalty that EDC can’t compensate. Thus, it reduces transmitter yields and increases cost.

Receiver: 10GBASE-LRM adds EDC chip cost to receiver and needs a linear detector and amplifier instead of other cheap digital equipment.

Package: 10GBASE-LRM requires a smaller package than 10GBASE-LX4. However, not like 10GBASE-S, 10GBASE-LRM requires higher-cost single-mode transmitter alignment for compatibility with mode conditioning patch cords.

Cords: 10GBASE-LRM needs mode conditioning patch cords for reliable link operation. And the cost is much higher than regular SMF or MMF fiber optic patch cords.

Through the comparison among these 10G optical transceivers, you may find which one costs fewer. 10GBASE-LRM transceiver is cheaper than 10GBASE-LX4, more expensive than 10GBASE-L and 10GBASE-S transceivers.

Conclusion

10GBASE-LRM is a multimode solution for 10 Gigabit Ethernet. Based on the above content, 10GBASE-LRM has some advantages over 10GBASE-LX4. It offers lower cost and smaller package. But the distance and reliability are not very ideal. Compared with 10GBASE-S, 10GBASE-LRM is not so good as to the cost, simplicity, reliability and distance capability. FS.COM provides various types of cost-effective 10GBASE transceivers, such as 10GBASE-LR, 10GBASE-SR, 10GBASE-ER, etc. Other compatible brands like Cisco, Juniper, Arista, Brocade are also available. Among so many choices, you must choose the most suitable solution for your network connection.

Originally published at http://www.fiber-optic-equipment.com