How to Select the Basic Materials of the LAN

Installing or designing network may pose a challenge as there are multiple optical solutions that meet the same specification or requirement. But by understanding the basic optical components and the specific performance requirements, you will be able to generate a cost-efficient bill of materials for your project. Thus before picking any products for your infrastructure, you must read this article.

Fiber Type
There are two basic fiber types: single-mode and multi-mode. Multi-mode fiber is graded by OM (optical multi-mode), the higher the OM grade, the better bandwidth performance you can expect. And it comes in both 50μm and 62.5μm core sizes with 50 μm multi-mode available in both standard (OM2) as well as a laser-optimized version (OM3/OM4). Single-mode are graded by OS (optical single-mode) and can run at OS1 and OS2, as described in TIA-568 C.3. Keep the consistency within your network is critical for long-term performance, therefore you shouldn’t mix new fiber type or performance with your old plant.

In addition, the cost of the components should be considered. The transceiver associated with single-mode fiber are more expensive than those for multi-mode. For example, the price of JG661A (compatible HP 40GBASE-LR4/OTU-3 QSFP+ transceiver) is much higher than JG325B (compatible HP 40GBASE-SR4 QSFP+ transceiver). The decision must be made to balance the performance and the cost. Single-mode system will provide for future expansion, yet multi-mode fiber is only for today and the near future. To sum up, single-mode fiber operate better at long reach while multi-mode fiber is ideal for short reach, choosing single-mode or multi-mode depends on your networks needs.

Termination Method
Deciding on a termination methods is typical affected by many factors. If your biggest concern is time, no epoxy/no polish connectors are probably your best choice. The fiber end faces are factory polished and easily installed with a tool kit. This types of termination method allows you to perform terminations quickly, but the cost is usually higher than that of epoxy and polish connector.

If your biggest concern is cost. epoxy and polish connectors might be a good fit because of their low initial price. This type of termination need considerable time to learn how to properly hand-polish connectors that meet specification, and it requires a large workspace to lay out the polishing papers, polishing pucks, epoxy, etc. If your work environment or network condition is not allowed, it is advisable not to select this method.

Fusion Splicer or Optical Connector
Keep in mind that whether to choose fusion splicing or a connector for your network will always need an experienced installer under adequate training. Fusion splicer, as we all know, is very expensive. If your company do not own one, it can be a large investment to make and you need to order the correct splice tray for your hardware and heart-shrinks to keep your splices intact. But if you already have a fusion splicer, fusion-spliced pigtails might be the right choice for you that can provide high quality results and easy to use in areas. The following picture shows a Fujikura FSM-80S Core Alignment Fusion Splicer.

Specifications, density, electronics interfaces and existing plant often drive connector choices. LC connector is favored for its maximum density and room-saving. It is also available in duplex from, which allows you to manage polarity by simply reversing the connector via a duplex clip. SC connectors feature an easy push/pull locking mechanism and are available in simplex and duplex forms. ST compatible connectors have a spring-loaded bayonet locking system that helps them stay in place but are only available in simplex versions.

Hardware
To determine the type of hardware you need, take into consideration the space that will be utilized for the network. If you are installing inside of a closet or other cramped quarters and need low density, wall mountable hardware is the best selection as it does not take up a lot of room. If racks are already in place, or if there is enough room to install them, rack-mount hardware is the best selection because it is sturdy and easy to access.

Additional Information
Designing a network may be a big project as you should take a lot of things into consideration. To make sure the high performance of you network, please think about all the aspects that I have written in this text. What’s more, there are three basic categories for cable: indoor, outdoor and indoor/outdoor. The types of cables you have to choose for your infrastructure depend on where the cables will be run. Fiberstore supplies a whole variety of optical equipment including fiber optical cables, optical transceivers, fusion splicer and optical connectors. Come to us to help your data transmission initiatives for future proof.

Design Consideration for 40G Ethernet Network

With the speed in the data center now increases from 10G to 40G, different optical technology and cabling are required. But at first we should figure out the design of 40G Ethernet network. There are several key factors that may affect the transition to 40G. This article today will pay special attention to those aspects that influence data center design consideration.

General Data Center Design
The principal goals in data center design are flexibility and scalability, which involve site location, building selection, floor layout, electrical system design, mechanical design and modularity. Furthermore the key to a successful data center facility: one that is sustainable in the long term; the other is to consider it as a receptacle for equipment and operations, as well as an integrated system, in which each component must be considered to be flexible and scalable. Figure 1 shows a typical data center infrastructure design utilizing preterminated optical solutions.

What Does MPO Connector Means for 40G Data Center?
While speeds have increased to 40G, optical connectivity has remained in a duplex format, whether SC or LC. With the advent of 40G/100G Ethernet, multi-fiber push-on (MPO) connector technology are now used at the electronics interface and further into the data center infrastructure design. MPO technology has displayed proven value in cassette-based data center physical layer installations.

The MPO is defined by TIA-604-5-C, Fiber Optic Connector Intermateability Standard. Type MPO (FOCIS-5) as an array connector that can support up to 72 optical fiber connections in a single connection and ferrule. While the MPO is versatile in the fiber count supported, the 12-fiber MPO is the version widely deployed. Many data center designs today use cassette-based duplex LC connectivity or MPO to duplex LC harnesses at the electronics interface, while 12-fiber MPO-based connectivity is used to connect the trunk cabling to each cassette or harness.

40G Standard Provision
The Habtoor STFA Soil Group (HSSG) has designated 40G to support high-performance computing clusters, blade servers, SANs and network-attached storage. For 40G deployment, the QSFP transceiver will utilize a 12-fiber MPO. Deployment of 40G over multi-mode fiber will be achieved with 4-Tx and 4-Rx fibers from the 12-fiber MPO (see in Figure 2). Each of these four “channels” will transmit 10G for the combined 40G transmission. Single-mode fiber transmission will remain duplex connectivity using course wavelength division multiplexing. The HSSG has also defined the transmission media for 40G to include:

• 40GBASE-SR4 (parallel optics)

100m on OM3/125m on OM4—10G on four fibers per direction

• 40GBASE-LR4(cWDM)

10km on single-mode fiber—4x10G 1300nm wavelength region

• 40GBASE-CR4

7m over copper—4x10G (twinax copper)

• 40GBASE-FR(Serial)

2km on single-mode—4x10G 1550nm

As noted above, the QSFP+ module is specified for use with different standard. The 40GBASE-SR4 is terminated with the MPO connector. For example, Cisco QSFP-40G-SR4 QSFP+ transceiver enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber female connectors.

For 12-fiber MPO cassette-based optical systems already installed, 40G migration is as simple as removing the existing cassette from the patch panel housings at the equipment and cross connects and replacing the cassette with an MPO adapter panel. Next, an appropriate 12-fiber MPO jumper would be used to cross-connect the trunk cabling as well as interconnect into the QSFP. Though not widely available currently, future preterminated system trunks may utilize 24-fiber MPO connections, both on the trunks and on the cassette. In this case, 40G deployment would require an interconnect harness terminated with two 12-fiber MPO connectors at the QSFP end, and one 24-fiber MPO at the trunk end. This would provide the needed interface with the 24-fiber MPO-based trunk and the 40G QSFP. A 24-fiber MPO jumper would be needed at the system cross connects to ensure polarity was maintained and that skew was within requirements.

Conclusion
The data center infrastructure must be reliable, manageable, flexible and scalable no matter who you are asking for requirements of data center design. It is the responsibility of the network designers to insure best compatibility of data center. As migrating to 40G, we have 40G QSFP and cables within MPO connectivity. Fiberstore supplies a variety of 40G QSFP modules and cables for you to choose from. Besides QSFP-40G-SR4, QSFP-40G-SR4-S and Cisco QSFP-40G-CSR4 are also available. If you are interested in our products, please contact us directly.

The 40G QSFP transceiver Comparison

Data center regularly went through great migration from 1G, 10G to 40G, 100G over the past few decade. Since IEEE 802.3ba standard defined the 40G Ethernet on June 17, 2010. The newest widely adopted optical transceivers is the QSFP+ that offers aggregated optical speeds of 40G. There are many variants for QSFP+ small from factor including LR4 (10km single-mode), IR4 (2km single-mode) or ESR4 and SR4 for short haul multi-mode. So what are they and what is the difference between them? The following passage will provide a satisfying answer to you.

QSFP optical transceivers have four separate 10G channels to simultaneously operating for supplying 40GbE network and sum up the capacity into a single channel. The following tables shows QSFP40G portfolio, of which 40GBASE-SR4, 40GBASE-LR4 and 40GBASE-ER4 are the most commonly used 40G physical layers.

1. 40GBASE-SR4
40GBASE-SR4 (short range) is a port type for multi-mode fiber and uses 850nm lasers. It uses four lanes of multi-mode fiber delivering serialized data at a rate of 10.3125 Gbit/s per lane. 40GBASE-SR4 has a reach of 100m on OM3 and 150m on OM4. There is a longer range variant 40GBASE-ESR4 with a reach of 300m on OM3 and 400m on OM4. This extended reach is equivalent to the reach of 10GBASE-SR. Take JG325A (see in Figure 2) as an example, it is HP compatible 40GBASE-SR4 QSFP+ transceiver. It primarily enables high-bandwidth 40G optical links terminated with MPO multi-fiber connectors and can also be used in a 4x10G module for interoperability with 10GBASE-SR interfaces.

2. 40GBASE-ER4
40GBASE-ER4 (extended range) is a port type for single-mode fiber being defined in P802.3bm and uses 1300nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength.

3. 40GBASE-LR4
40GBASE-LR4 (long range) is a port type for single-mode fiber and uses 1300nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength. Take FTL4C1QE1C as an example, it is Finisar FTL4C1QE1C  (see in Figure 3) compatible 40GBASE-LR4 QSFP+ transceiver supporting link lengths of 10km at a wavelength of 1310nm.

Comparison of These Three 40GBASE Standards
Through the above definitions of each type of 40G physical layers, you may have a further understanding of them. Now, we are comparing them one by one. 40GBASE-SR4 is for multi-mode fiber while 40GBASE-LR4 and 40GBASE-ER4 is a port type for single-mode fiber. The multi-mode solutions require special MPO fiber ribbons (multi-strand optical cables) to transport the 4 different 10G optical connections. Single-mode solutions use only two strands of fiber and combine the 4 channels using inexpensive CWDM technology. This gives a tremendous advantage, simplifying the connectivity to standard LC optical connectors and thus reducing costs further.

In addition, 40GBASE-LR4 QSFP+ transceivers are most commonly deployed between data-center or IXP sites with single mode fiber. 40GBASE-SR4 QSFP+ transceivers are used in data centers to interconnect two Ethernet switches with 12 lane ribbon OM3/OM4 cables. And from the above figure, we can know that they support different transmission distance in different wavelengths and with different connectors.

Summary
To sum up, 40GBASE-SR4, 40GBASE-LR4 and 40GBASE-ER4 are distinguished with each other in several different features—wavelength, connector, transmission distance, etc. Fiberstore offers a wide variety of high-density and low-power 40GBASE QSFP+ transceiver modules. They are the best-selling products of our company for its large stocks, competitive price and high quality. In addition, there are also a promotion for MTP cables. For more information, please contact us directly.

Reference:
http://www.ieee802.org/3/100GNGOPTX/public/mar12/plenary/cole_01b_0312_NG100GOPTX.pdf