Considering Three Aspects Before Migrating to 40G

The dramatic growth of bandwidth requirements in data centers has led to the worldwide use of higher-performance optical products for network scalability, management, flexibility and reliability. Currently, 10GbE (Gigabit Ethernet) can’t meet the increasing needs of high speed transmission well for such applications as Big Data, cloud and Internet of Things being introduced in many industries. As such, network migration to 40/100G has already been the industry consensus.

But as the cost for 100G is far beyond what most enterprises can afford and the technology for 100G is still not mature enough, 40G has been a better solution for its lower cost and maturer technologies compared to 100G. Nowadays, some manufacturers are battling for the 40G market, which drives down the 40G deployment price, leading to the even wider deployment of 40G infrastructure. When migrating from 10G to 40G, three aspects should be considered: fiber optic transceiver, transmission media, and pre-terminated MPO assemblies.

Fiber Optic Transceiver

For any telecommunication network, fiber optic interconnection is of great importance. Photoelectric conversion is a necessary part in fiber optic network. The function of fiber optic transceiver is photoelectric conversion, which makes it one of the most commonly used components in the data center.

As for 40G transceivers, two different package forms are available: QSFP+ (Quad Small Form-factor Pluggable Plus) and CFP (C Form-factor Pluggable), with the former more widely-used than the latter. A single 40G fiber optic transceiver may not be expensive. But what a medium-sized data center needs is thousands of optical transceivers, meaning a large sum of money to be spent. In such a case, third party transceivers that are compatible with a variety types of switches come into point. They have the same performances that the original brand transceivers have, but cost less money. When selecting 40G compatible transceivers, cost and quality are very important. Choosing the compatible 40G transceivers from Fiberstore can ensure 100% compatibility and interoperability. The picture below shows the testing of Cisco compatible QSFP-40G-SR4 transceivers on a Cisco switch to ensure its compatibility and interoperability.

QSFP-40G-SR4, under test

Transmission Media

Allowing for several situations that may exist, the IEEE 802.3ba specified the different transmission media for 40G links, including the following listed media:

  • 40GBASE-CR4: 40Gb/s Ethernet over copper cable in short transmission distance.
  • 40GBASE-SR4 (eg. QFX-QSFP-40G-SR4): 40Gb/s Ethernet over four short-range multi-mode fiber (MMF) optic cables.
  • 40GBASE-LR4: 40Gb/s Ethernet over four wavelengths carried by a signal long-distance single-mode fiber (SMF) optic cable.

There also exists hybrid cabling solutions for 40G applications, like QSFP to 4SFP+ breakout cabling assembly. Take QSFP-4SFP10G-CU5M for example, this product listed in Fiberstore is the QSFP+ to 4 10GBASE-CU SFP+ passive direct-attach copper transceiver assembly with 5-meter reach.

QSFP to 4SFP+ breakout cabling assembly, for short reach, 5m

Question occurs: fiber optic cable or copper cable, which should be used in 40G migration? Copper is cheaper. But it can only support 40G transmission limited to several meters. SMF supports the longest 40G transmission distance up to 40 km. As for MMF, OM3 and OM4 are suggested to support short distance transmission. The longest distance that OM3 can support for 40G transmission is 100 m. OM4 can support a longest 40G transmission distance of 150 m. The selection of transmission media should depend on the specific applications.

MPO Assemblies for 40G

The IEEE 802.3ba standard also specifies multi-fiber push-on (MPO) connectors for standard-length MMF connectivity. Most of the 40G multi-mode Ethernet transceivers are based on the MPO technology. It is wise to increase fiber optic density by using MPO technology, but a new problem arises. As the fiber number increased, the cabling and splicing difficulty in data center increased. Unlike traditional two-strand fiber connections, MPO connectors cannot be field terminated easily. Thus, most of the data centers choose the pre-terminated MPO assemblies in 40G deployment, which is more reliable and can save more human labor. Before cabling, determine the cabling lengths and customized pre-terminated MPO assemblies with manufacturers would save a lot of time and money.

Conclusion

Using compatible third party transceivers of high quality for 40G links saves a lot of money. Taking specific applications and characteristics of 40G transmission media into consideration can also help you to save cost. Pre-terminated MPO assemblies are necessary for flexible and manageable cabling in 40G deployment. With these information in mind, cost-effective 40G migration is at the corner.

Pluggable Transceivers Used in Data Centers

Today’s data centers are going through unprecedented growth and innovation as emerging optical standards and customers’ demands for higher-level networking services converge. Bandwidth, port density and low-power demands come as the main drivers that populate the deployment of fiber optic networks. And in fiber optic network implementations, pluggable transceivers provide a modular approach to safe-proof network design and become the ideal choice to meet the ever-changing network needs in data centers. This text just mainly introduces pluggable transceivers deployed in data centers.

A Quick Question: What Are Pluggable Transceivers?

Pluggable transceivers are transceivers that can be plugged into routers, switches, transport gear, or pretty much any network device to transmit and receive signals. They are hot swappable while the device is operating, standardized to be interchangeable among vendors, capable of operating over many different physical medium and at different distances. For instance, pluggable transceivers can work through copper, through fiber optic cables available in both single-mode fibers (SMFs) and multi-mode fibers (MMFs), realizing 100m, 300m, 10km, 80km distance reach, etc. In addition, these hot-swappable transceivers are also able to support a wide variety of speeds, like 1Gbit/s, 10Gbit/s, 40Gbit/s, 100Gbit/s, or even higher.

Pluggable Transceiver – Standards & Protocols

Just as what has been mentioned above, pluggable transceivers are interchangeable. These interchangeable transceivers allow a single device to operate with a wide selection of protocols and functions. Listed below are commonly-used pluggable transceiver standards and protocols.

SFP—The small form-factor pluggable (SFP) supports a wide range of protocols and rates, such as Fast and Gigabit Ethernet (GbE), Fibre Channel (FC), and synchronous optical networking (SONET) for dual and bidirectional transmission. SFP medium are available in SMF, MMF, and copper. For MMF media, there exists 1000BASE-SX port type used in 1GbE applications. Take J4858C for example, this HP 1000BASE-SX SFP can realize a maximum of 550m reach at 1.25 Gbit/s over MMF.

J4858C, HP 1000BASE-SX SFP

SFP+—The enhanced small form-factor pluggable (SFP+) is an enhanced version of the SFP, supporting data rates up to 16Gbit/s. It was first published on May 9, 2006, and version 4.1 was published on July 6, 2009, supporting 8Gbit/s FC, 10GbE and Optical Transport Network standard OTU2. SFP+ is a popular industry format supported by many network component vendors.

XFP—The XFP (10G SFP) is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. Its principal applications include 10GbE, 10Gbit/s FC, SONET at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s Optical Transport Network (OTN) OTU-2, and parallel optics links.

QSFP—The Quad Small Form-factor Pluggable (QSFP) is a also a compact, hot-pluggable transceiver used for data communications applications. QSFP+ transceivers are designed to carry Serial Attached SCSI, 40GbE (100G using QSFP28), QDR (40G) and FDR (56G) Infiniband, and other communications standards. They increase the port-density by 3x-4x compared to SFP+ modules. In 40GbE applications, these QSFP+ transceivers establish 40G links with distances up to 300m over MMF, and 40km over SMF. QSFP can also take copper as its media option when the required distance is short. Like QSFP-4SFP10G-CU5M, this product is the QSFP to 4 10GBASE-CU SFP+ direct attach passive copper cable assembly designed for relatively short reach, that is 5m. The image below just shows what this QSFP-4SFP10G-CU5M product looks like.

QSFP-4SFP10G-CU5M, QSFP to 4 10GBASE-CU SFP+

CFP—The C form-factor pluggable (CFP) is a multi-source agreement (MSA) to produce a common form-factor for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 100 Gigabit Ethernet systems.

Conclusion

Pluggable transceivers offer distance extension solutions, allowing flexibility in network reach and easy replacement in the event of component failures. They are the answer to today’s network architecture and performance demands. Fiberstore supplies various pluggable transceivers supporting different speeds, like SFP (J4858C), SFP+, XFP, QSFP, CFP, etc. Additionally, their transmission medium available in fiber and copper can also be found in Fiberstore. For more information about pluggable transceivers, you can visit Fiberstore.