Tag Archives: OM4

Why Should We Choose 40GbE?

In today’s server networks, 10GbE (Gigabit Ethernet) has become commonplace. However, for some workloads, 10GbE might not be enough. As data centers virtualize more of their servers and storage, the need for speedy network connections increases. Believe it or not, the 40GbE (Gigabit Ethernet) era is already upon us. The standard has long been ratified, and products are shipping. However, there has been some debate as to whether IT managers should hold off on deploying the 40GbE technology and bide their time waiting for 100GbE to become commercially available. Why should we choose 40GbE?

40GbE: A Closer Look

40GbE is an Ethernet standard developed by the IEEE 802.3ba Task Force that support sending Ethernet frames at 40 gigabits per second. It also addresses physical layer specifications for communication across backplanes, copper cabling, multi-mode fiber and single-mode fiber. At the heart of the 40GbE network layer is a pair of transceivers connected by a cable, for example OM4 or OM3 fiber cable. The transceivers, in turn, are plugged into either network servers or a variety of components including interface cards and switches. 40GbE is becoming commonly applied to access links to connect servers as Figure 1 indicates.

40GbE application

Advanatges of Choosing 40GbE

40GbE can be effectively deployed today in aggregation links in data center networks. The standards for 40 GbE have been around as a specification, and a number of routers, switches, and network cards already operate at this speed. Vendors such as Cisco, Dell’s Force10, Mellanox, HP, Extreme Networks, Finisar, and Brocade offer such hardware. And another attractive characteristic of 40GbE is broad applications and design flexibility. Considering the productivity gains and decrease in operating expense (OPEX), migrating to 40GbE will prove very cost-effective for those who do it right.

In migrating to 40GbE, some networks will be able to use their current 10GbE switch chassis and just upgrade their line cards and transceivers. Deploying a QSFP+ form factor transceiver will provide the flexibility to migrate from 10GbE to 40GbE. With regards to cabling, OM3 or OM4 is optimal for the 40GbE or 100GbE data center environment. The major difference is in the maximum span distances. In a 10GbE network, OM3 fiber can span up to 300m while OM4 supports even longer channels. In a 40GbE or 100GbE environment, OM3 can be used up to 100m and OM4 up to 150m according to the IEEE802.3ba standard. For applications approaching 150m, the cable should be terminated with low loss connectors.

Conclusion

It is like building an eight-lane superhighway with dirt off ramps and interchanges. Unless you upgrade everything, it is totally useless. You bump into things like immature network interface card drivers that can hang up your entire system. 40GbE is like a bridge which enbales you to prepare for higher needs. Fiberstore is a professional manufacturer and supplier of a complete range of 40GbE transceiver modules and cables. We provide compatible QSFP+ transceivers as alternatives to those branded by Cisco, HP, Juniper, Brocade, Finisar and so on. For example, Brocade QSFP+ and Finisar QSFP+ offer by us are high-performance and cost-effective products to fulfill your requirements.

Fiber Types and Associated Transceivers

An optical fiber is a flexible filament made by pure glass or plastic fiber used to transmit the light. There are two types of fiber: single mode fiber (SMF) and multimode fiber (MMF). Each kind of fiber includes several categories. Different category supports different transmission speeds and wavelengths. So there must be suitable optical transceivers connecting with related fibers for the network applications. The article tells about some categories of SMF and MMF and the associated interface type of transceivers.

Types of SMF and Associated Transceivers

The common SMF is defined in ITU G.652 standard. ITU G.652 is non-dispersion-shifted single mode fiber (NDSF). This fiber is optimized in 1310nm range. In order to eliminate the problems encountered by transmissions in the third window, other fiber types were developed. Dispersion-shifted fibers (DSF) with a zero dispersion at 1550 nm were defined in ITU G.653. Thus, attenuation is minimized so that longer distance cables are possible. However, even though this fiber type eliminates the problem for transmissions of single wavelengths at 1550 nm, it is not suitable for wavelength multiplexing applications as WDM transmissions can be affected by another non-linear effect called four-wave mixing. This brought non-zero dispersion shifted fibers (NZDSF) in the ITU G.655 standard. For this fiber type, the zero dispersion is shifted just outside the C-Band, usually around 1510 nm. This helps limiting the chromatic dispersion as the zero dispersion remains close enough to the transmission band.

For SMF applications, there are various of transceivers to be used. These transceiver interfaces are defined by IEEE 802.3. They are used to transmit at 1310nm (ITU G.652) and 1550nm (like ITU G.653) wavelengths for long-haul transmission applications. The following figure shows us the different single mode fibers and associated interface types of transceivers.

Figure1. SMF/Interface Type
Single Mode Fibers & Interface Type

Types of MMF and Associated Transceivers

MMFs are described in ISO 11801 standard – OM1, OM2, and OM3 – which is based on the modal bandwidth of the MMF. OM4 was finalized in August 2009, and was published by the end of 2009 by the TIA. The letters “OM” stand for optical multi-mode. OM1 has a core size of 62.5 nm. It is most commonly used for 100 Megabit Ethernet applications. OM2 has a core size of 50 um. It supports 10 Gigabit Ethernet at lengths up to 82 meters. OM3 also has a core size of 50 um. It supports 10 Gigabit Ethernet at lengths up to 300 meters. Besides OM3 is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. OM4 uses a 50um core but it supports 10 Gigabit Ethernet at lengths up to 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters.

Like SMF, there are also corresponding transceivers applied with MMF. The differences are wavelength and transfer distance. For MMF is suitable for short distance transmission at the wavelengths of 850 nm and 1300 nm. Figure 2 shows the different types of MMF and associated interface type of transceivers.

Figure 2. MMF/Interface Type
Multimode Fibers & Interface Type

Fiberstore offers a full line of single mode and multimode fiber cables for all network applications. There are also a wide range of optical transceivers, such as SFP, SFP+, XFP, 40G QSFP and PON transceiver. All the transceivers can be connected with either SMF or MMF. And you can have the flexibility to custom the cables and transceivers to fit your specific requirements.