40G Transceivers With MTP/MPO Interface vs. 40G Transceivers With LC Interface

With 40 Gigabit Ethernet commonly deployed in most data centers, it is very essential for the data center managers to employ the suitable 40G devices like 40G QSFP+ transceivers. Nowadays, various 40G transceivers are available on the market, but mainly there are two interfaces adopted by 40G QSFP+ transceivers—MTP/MPO and LC. What’s the difference between these two interface types? This article will have an analysis of the 40G QSFP+ transceivers with MTP/MPO interface and 40G QSFP+ transceivers with LC interface.

Transmission Distance and Cable Type

Generally, the 40G QSFP+ transceivers with LC interface are used for long distance transmission over single-mode fiber (SMF), and QSFP+ transceivers with MTP/MPO interface are utilized for short distance transmission over multimode fiber (MMF). However, for some 40G transceivers with MTP/MPO interface, such as 40GBASE-PLRL4, and 40GBASE-PLR4, they can support long distance transmission over SMF.

Working Principle

40G QSFP+ transceivers with LC interface—In the transmit side, 4-channel 10G serial data streams are passed to laser drivers. The laser drivers control directly modulated lasers (DML) with wavelengths. Then the output of the four DMLs are optically multiplexed to a SMF through an industry-standard LC connector, combining as 40G optical signal. In the receive side, the 40G optical signals are demultiplexed into 4 individual 10G channels with different wavelength. Each wavelength light is collected by a discrete photo diode, and then outputted as electric data after amplified by a TIA. In this process, a 4-wavelength CWDM multiplexer and demultiplexer is used over a pair of single-mode fibers.

40G QSFP+ transceivers with MTP/MPO interface—In the transmit side, the transmitter converts parallel electrical input signals into parallel optical signals through the use of a laser array. Then the parallel optical signals are transmitted parallelly through the multimode fiber ribbon. In the receive side, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.

Note: there are some 40G transceivers with MTP/MPO interface working over SMF as mentioned above. For this kind of PSM (a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector) QSFP+, it offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G over SMF. That is to say, 8 single-mode fibers are used to achieve parallel transmission.

4x10G Connectivity

For the 40G QSFP+ transceivers with LC interface, they cannot be split into 4x10G as they use 4 wavelengths on a pair of single-mode fibers and do not lend themselves to “splitting” into 4 pairs without substantial complexity to split out the wavelengths. For the 40G QSFP+ transceivers with MTP/MPO interface, they can be used in 4x10G connectivity via an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 40G module to four 10G optical interfaces.

FS.COM 40G Transceivers Solution

As a professional manufacturer and supplier in optical communication industry, FS.COM provides a series of 40G transceivers to meet various network demands. The following table lists the generic ones. Besides the generic ones, the 40G transceivers compatible with other brands, such as Cisco, Juniper are also available. Most of them are in stock now and can be shipped the same day after order.

Model	Interface Type	Cable Type	Max Cable Distance
40GBASE-CSR4	MTP/MPO	MMF	400 m over OM4 MMF
40GBASE-SR4	MTP/MPO	MMF	150 m over OM4 MMF
40GBASE-PLRL4	MTP/MPO	SMF	1.4 km
40GBASE-PLR4	MTP/MPO	SMF	10 km
40GBASE-LR4	LC duplex	SMF	10 km
40GBASE-LR4L	LC duplex	SMF	2 km
40GBASE-ER4	LC duplex	SMF	40 km
40GBASE-LX4	LC duplex	MMF/SMF	OM3/OM4 MMF: 150 m, SMF: 2 km
40GBASE-SR BiDi	LC duplex	MMF	150m@OM4/100m@OM3/30m@OM2
40GBASE-LR4 CFP	SC duplex	SMF	10 km

Originally published: www.fiberopticshare.com/40g-transceivers-mtpmpo-interface-vs-40g-transceivers-lc-interface.html

Deploy 40GBASE-UNIV Transceiver to Achieve More Cost-effective Data Center Upgrade

Due to server consolidation, virtualization, and performance improvements, there is a growing need in the data center for 40GbE switch connections. For many data center operators, this upgrade and conversion is more challenging based on two primary factors. Firstly, the potential for a reconfiguration of the physical layer of the network based on reduced reach of the OM3/OM4 multimode optics from 10GBASE-SR (300/400 m) to 40GBASE-SR4 (100/150 m). Secondly, the existing fiber optic cabling plant may need to be upgraded based on the additional fiber count needed to support the IEEE-defined 40GBASE-SR4 parallel optics. These two factors bring the 40GBASE-UNIV optical transceiver to market.

What Is 40GBASE-UNIV QSFP+ Transceiver?

The 40GBASE-UNIV QSFP+ is a pluggable optical transceiver with a duplex LC connector that can operate with both single-mode fiber and multimode fiber. Generally, the transmission distance could be up to 150 m over OM3/OM4 and up to 2 km over SMF. It has 4 channels of 10G multiplexed inside the module to transmit and receive an aggregate 40G signal over a single pair (2 strands) of fiber. It is called “Universal” because of its ability to operate with both SMF and MMF without the need for any software/hardware changes to the module or any additional hardware in the network. The 40GBASE-UNIV QSFP+ offers a very cost-effective connectivity solution and unique value proposition for data centers to migrate from 10G to 40G with minimal disruption over existing single-mode and multimode infrastructure.

Benefits of 40GBASE-UNIV QSFP+ Transceiver

40G transmission over 2 fibers—Existing 40G transceiver for short reach, such as 40GBASE-SR4, utilizes four independent 10G transmitters and receivers for an aggregate 40G link, requiring a total of 8 fibers per link. It uses an MPO-12 connector and requires a parallel multimode fiber (OM3 or OM4). This is four times more fiber than is required for 10G short reach links (see Figure 1). The 40GBASE-UNIV transceiver also uses four transmitters and four receivers but has built in optical multiplexing and de-multiplexing, which results in a duplex connector and hence operates over the same duplex fiber infrastructure as 10GBASE-SR.

Figure. 1

Save cost—Besides the reduced number of fibers per 40G link, the 40GBASE-UNIV transceiver offers significant cost savings in the overall fiber cable infrastructure. Customers retain the existing structured cabling system as is for 10G to 40G migration, but they have to change the patch cables and patch panel infrastructure to use a 40GBASE-SR4 QSFP+.

The Figure 2 shows typical 1-trunk cable infrastructure for QSFP+ SR4, and Figure 3 shows the associated cabling cost with 40G link as in Figure 2.

Figure. 2

Figure. 3

Figure 4 shows typical 1-trunk cable infrastructure for QSFP+ UNIV, and Figure 5 shows the cabling cost associated with 40G link as in Figure 4.

Figure. 4

Figure. 5

A saving of over 75% on the cabling equipment alone is realized from the UNIV transceiver. The significant cost savings make the 40GBASE-UNIV transceiver an ideal choice for 40G leaf-spine connections with existing multimode fiber.

Easy migration to 100G with single-mode fiber—As data rates increase from 40G to 100G and beyond to 400G, there is a strong desire for data centers to move to single-mode for cost effectiveness and to future proof the fiber infrastructure. Due to the limitations of multimode transceivers to support existing distances with ever increasing data rates, migrating to 100G and 400G in the future will be simpler with single-mode fiber. However, the major pain point in this transition has traditionally been the optics cost. Single-mode transceivers typically cost up to 4 times more compared to multimode transceivers. The 40GBASE-UNIV transceiver has broken this barrier with the following reasons:

• Cost of the optical transceiver is less than 2 times of multimode transceiver
• Same optics for SMF and MMF
• Investment protection as the same optics can be used when migrating from MMF to SMF
• Compatible with industry standard 40GBASE-LR4 and the LR4-Lite (1km version)

Figure 6 shows typical 1-trunk single-mode fiber cable infrastructure for QSFP+ UNIV, and Figure 7 shows cabling cost associated with a 40G link using all single-mode fiber infrastructure as in Figure 6.

Figure. 6

Figure. 7

Conclusion

The 40GBASE-UNIV transceiver enables data centers to run at 10G today to seamlessly upgrade to 40G without having to re-design or modify the cable infrastructure. It also offers a transition path for customer planning migrations to single-mode fiber in data centers with a single transceiver that bridges the gap between multimode and single-mode optics. FS.COM provides 40GBASE-UNIV transceivers and the associated optics for 40G and 100G connectivity. All of the optics are tested on the corresponding equipment to ensure the excellent performance with the customers’ devices.

 Originally published: www.fiberopticshare.com

40G Ethernet Migration Strategy Over Multimode Fiber

With the increasing network bandwidth to meet the global IP traffic demand, there will be a need to upgrade to 40G Ethernet links for switch to server and storage area network connections in data centers. And the biggest market for 40G Ethernet (40 GbE) is in data centers for interconnection links with servers and storage area networks. So this article will talk about migration strategy for 40G Ethernet over multimode fiber.

40G Ethernet Standard

 

IEEE published the IEEE 802.3ba standard for 40 Gigabit Ethernet in June 2010. The following table illustrates the capabilities of different grades of multimode fibers (OM1, OM2, OM3 and OM4) to support different Ethernet applications. Only the laser optimized multimode fibers OM3 and OM4 are capable of supporting 40G Ethernet. The cabling requirements for 40GBASE-SR4 will be focused and guidance on an effective migration strategy to transition form 10G to 40G will be provided.

 

40G Ethernet Over Multimode Fiber

 

40G Ethernet over multimode fiber uses parallel optics at 10Gb/s per lane. One lane uses 1 fiber for each direction of transmission. 40G requires 8 fibers. The concept of parallel transmission at 10 Gigabits per lane is illustrated below. The minimum performance that is needed to support 40G over multimode fiber is OM3 fiber for a distance of 100 meters. Cabling with OM4 fiber provides the capability to extend the reach up to 150 meters.

 

Media Dependent Interface (MDI)

 

The MDI is the physical interface that connects the cabling media to the network equipment. For multimode fiber, the media dependent interface is the MPO adapter that meets the dimensional specifications of IEC 61754-7 interface 7-3. The corresponding MPO female plug on the optical fiber cable uses a flat interface that meets the dimensional specifications. 40 GbE uses the MPO connector interface at the MDI and uses a 12 position MPO connector interface that aligns 12 fibers in a single row. Four transmit fibers are used on one side and four receive fibers are used on the opposite side of the MPO connector, for a total of eight fibers. The middle four fiber positions are not used.

Migration Path From 10G to 40G for Multimode Fiber

 

Migrating from 10G (that uses two fibers in either a SC Duplex or a LC Duplex connector) to 40G will require a lot more fibers and a different type of connector. The way that optical fiber cabling is deployed for 10G can facilitate an easier migration path to 40G. An effective migration strategy needs to provide a smooth transition to the higher Ethernet speeds with minimum disruption and without wholesale replacement of existing cabling and connectivity components.

Optical fiber cabling is commonly deployed for backbone cabling in data centers for switch to switch connections and also for horizontal cabling for switch to server and storage area network connections. The use of pre-terminated optical fiber cabling can facilitate the migration path to 40G. A pre-terminated cable assembly containing 24 OM4 multimode fibers with two 12-fiber MPO connectors at both ends plugs into the back of a breakout cassette that splits the 24 fibers into 12 LC duplex connectors at the front of the cassette. It is necessary to provide some 40G connections, either as a replacement of or as an addition to the existing 10G connections.

The first case: if upgrading from 10G to 40G, one or more of the LC duplex cassette/cassettes can be replaced with 12 MPO adapters. The MPO adapters are designed to fit in the same opening as the cassettes. Fiberstore offers a high-density 18 MPO adapter with the same overall physical dimensions as 12 MPO adapter. This is an upgrade path from 10G to 40G that does not require any additional space and reuses the same patch panels. For instance, the 12 LC duplex cassettes could be replaced with either a 12 MPO or 18 MPO adapters as needed.

The second case: if it is required to add some 40G connections while retaining the 10G connections, a high-density cassette containing 18 LC duplex connections in the same space as a 12 LC duplex cassette would be used. Three of the 12 duplex cassettes can be replaced with three 18 LC Duplex cassettes, thus maintaining the 48 10G connections while freeing space for either a 12 MPO or 18 MPO adapter providing up to 18 additional 40G connections. The requisite number of additional fiber cable assemblies in multiples of 12 fibers are provided as needed.

Summary

 

Pre-terminated optical fiber cabling provides a seamless migration path to 40 Gigabit Ethernet using the same infrastructure by adding pre-terminated trunk cable assemblies and MPO adapter frames as needed. The use of Fiberstore’s pre-terminated cabling facilitates the migration to 40G Ethernet from 10G Ethernet networks today.

Article source: www.fiberopticshare.com/40g-ethernet-migration-strategy-over-multimode-fiber.html

Data Center 40G Migration with OM3 and OM4 Optical Connectivity

Why Migrate to 40G

With the quick development in data center, cabling infrastructures should provide manageability, flexibility and reliability. Deployment of optical connectivity solutions enables for an infrastructure meeting these requirements for current applications and data rates. Scalability is another key factor that needs to consider when choosing the type of optical connectivity. It refers to not only the physical expansion of the data center with respect to additional servers, switches or storage devices, but to the scalability of the infrastructure to support a migration path for increasing data rates. As technology evolves and standards are completed to define data rates such as 40G/100G, Fibre Channel (32G and beyond) and InfiniBand (40G and beyond), the cabling infrastructures installed today need to provide scalability to accommodate the need for more bandwidth in support of future applications. Moreover, current data rates cannot meet the needs of the future with the rising demand to support high-bandwidth applications. 40G technologies and standards, however, can support future networking requirements. Thus, a migration to 40G is required.

40 Gigabit Ethernet Standard

Ratified in June 2010, 802.3ba standard provides a guidance for 40G transmission with multimode and single-mode fibers. And this standard does not have guidance for Cat UTP/STP copper cable. OM3 and OM4 are the only multimode fibers included in the standard. Due to the 850nm VCSEL modulation limits, multimode fibers utilize parallel optics transmission instead of serial transmission. Single-mode fiber guidance utilizes duplex fiber WDM (wavelength-division multiplexing) serial transmission.

Compared to single-mode fiber, multimode fiber offers a significant value proposition for short length interconnects in the data center. Unlike traditional serial transmission, parallel optics transmission utilizes an optic module interface where data is simultaneously transmitted and received over multimode fibers. The 40GBASE-SR4 supports 4 x 10G on four fibers per direction.

Cabling Performance Requirements for OM3/OM4

When evaluating the performance needed for the OM3 and OM4 cabling infrastructure, the following criteria should be considered. Each of the criteria would have an impact on the cabling infrastructure’s ability to meet the standard’s transmission distance of 100 meters over OM3 fiber and 150 meters over OM4 fiber.

Bandwidth is the primary criteria. OM3 and OM4 fibers are optimized for 850nm transmission and have a minimum 2000 MHz∙km and 4700 MHz∙km effective modal bandwidth (EMB). Fiber EMB measurement techniques are utilized today. The minimum EMBc (Effective Modal Bandwidth calculate) method combines the properties of both the source and fiber. With a connectivity solution using OM3 and OM4 fibers that have been measured using the minEMBc technique, the optical infrastructure deployed in the data center will meet the performance criteria set forth by IEEE for bandwidth.

Insertion loss is a critical performance parameter in current data center cabling deployments. Total connector loss within a system channel impacts the ability to operate over the maximum supportable distance for a given data rate. The supportable distance at data rate decreases with total connector loss increasing. The 40G standard specifies the OM3 fiber to a 100m distance with a maximum channel loss of 1.9 dB, which includes a 1.5 dB total connector loss budget. OM4 fiber is specified to a 150m distance with a maximum channel loss of 1.5 dB, which includes a 1.0 dB total connector loss budget. The maximum cable fiber attenuation is 3.5 dB/km at 850 nm. So the insertion loss specifications of connectivity components should be evaluated when designing data center cabling infrastructures. With low-loss connectivity components, maximum
flexibility can be achieved with the ability to introduce multiple connector matings into the connectivity link.

Summary

Cabling deployed in the data center today must be selected to provide support of data rate applications of the future. To achieve this purpose, OM3 or OM4 is a must. They provide the highest performance for today’s needs. With 850nm EMB of 2000 MHz∙km and 4700 MHz∙km, the fibers provide the extended reach required for structured cabling installations in the data center. Except the performance requirements, the choice in physical connectivity is also important. Utilizing MTP-based connectivity in today’s installations provides ways to migrate to multifiber parallel optic interface when needed. Therefore, MTP-based connectivity using OM3 and OM4 fiber is the ideal solution in the data center. It can be installed for use in today’s applications, while providing an easy migration path to future higher speed technologies.
 

Article source: www.fiberopticshare.com/data-center-40g-migration-with-om3-and-om4-optical-connectivity.html