How Much Do You Know About DDM/DOM Function?

DDM which stands for digital diagnostics monitoring is specified by the industry-standard SFF-8472. Modern optical SFP transceivers can support standard digital diagnostics monitoring (DDM) functions.which is also known as digital optical monitoring (DOM). What makes these transceivers with DDM/DOM function different from the traditional modules? This article will give you the answer.

What is Digital Diagnostic Monitoring (DDM)?

Very often, we can see GLC-LH-SMD, or on the label of modern transceivers. Actually, the “D” in GLC-LH-SMD represents the DDM function we are talking about today. When choosing fiber optical transceivers in the market, you may have the option with or without DDM/DOM. At present, most of high-end switches require the SFPs with DDM functions. Switches with DDM/DOM allow users of distributed networks to be more proactive in maintaining their network using this standard optical interfaces. Because modules with this capability give the end user the ability to monitor parameters of the SFP, such as optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage, in real time.

Basic Principles of DDM Function

Devices with DDM function can provide component monitoring on these applications. The SFF-8472 added DDM interface and outlined that DDM interface is an extension of the serial ID interface defined in GBIC specification, as well as the SFP MSA. DDM interface includes a system of alarm and warning flags which alert the host system when particular operating parameters are outside of a factory set normal operating. Thus, DDM interface can also enable the end user with the capabilities of fault isolation and failure prediction which will be introduced in the following part.

What can DDM Function Realize?

• Component Monitoring: The DDM enables the end user to monitor the five key parameters in the performance of the fiber optical transceivers: internal temperature, DC supply voltage, transmitter bias current, transmitter output power, and receiver optical signal level. Integrated DDM functionality also incorporates warnings and alarms to monitor these parameters.
• Fault Isolation: The DDM function can be used to isolate the particular location of fault in fiber optic network system. Combining the DDM interface status flags, transceiver hard pins and diagnostic parametric monitor data the specific location and cause of a link failure can be pinpointed.
• Failure Prediction: The DDM can also be used to help in failure prediction on fiber optic links, which is based on the transceiver parametric performance. Although, this application is not yet fully mature, but there is still room for improvement. There are two basic types of failure conditions that can be seen on fiber optic transceivers. One is device faults which usually happen in transmitter performance due to nature of semiconductor lasers. The other is high error rate conditions when a transceiver operates at its signal-to-noise limit. It happens more often in fiber optic receiver performance.

From the above analysis, we can see that fiber optical transceivers with DDM help to ensure that the business can be proactive in preventative maintenance of the network and ensure business continuity. Fiberstore offers an enormous range of optical transceivers with DDM function, among which there are Cisco GLC-SX-MMD, HP J9151A and so on. All these transceiver modules are 100% compatible with major brands like Cisco, HP, Juniper, Nortel, Force10, D-link, 3Com. They are backed by a lifetime warranty, and you can buy with confidence.

Which Do You Prefer: 10GBASE-T or SFP+ DAC?

A variety of technological advancements and trends are driving the increasing need for 10 GbE in the data center. IT managers are now faced with the challenge of selecting the appropriate 10-gigabit physical media, as 10 Gigabit Ethernet (10GE) is offered in two broad categories, optical and copper, with the latter being the most commonly used means for connectivity in data centers. This article addresses the tradeoffs between the effective choices in copper connectivity 10GBase-T and SFP+ direct attach cable (DAC).

What is 10GBASE-T and Why Choose It?

10GBASE-T is an IEEE 802.3an standard which supports the creation of technology that is capable of transmitting 10 Gigabit Ethernet up to 100 meters over four pairs of CAT-5 balanced copper cabling system. It is an exciting technology that provides end users with cost-effective media to achieve 10Gbps data rates.

Like all BASE-T implementations, 10GBASE-T works for lengths up to 100 meters, giving IT managers a far greater level of flexibility in connecting devices in the data center. With flexibility in reach, 10GBASE-T can accommodate either top of the rack, middle of row, or end of the row network topologies. This gives IT managers the most flexibility in server placement since it will work with existing structured cabling systems. Because 10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in existing 1 GbE switch infrastructures in data centers that are cabled with CAT6 and CAT6A (or above) cabling, enabling IT to keep costs down while offering an easy migration path to 10 GbE.

What is SFP+ DAC and the Benefits of It?

SFP+ direct attach cable (DAC) is a fixed assembly that is purchased at a given length, with the SFP+ connector modules permanently attached to each end of the cable. SFP+ DAC provides high performance in 10 Gigabit Ethernet network applications, using an enhanced SFP+ connector to send 10 Gbps data through one paired transmitters and receivers over a thin twinax cable or fiber optic cable. The 10G SFP+ DAC is designed to use the same port as an optical transceiver, but compared with optical transceivers, the connector modules attached to the cable leave out the expensive optical lasers and other electronic components, thus achieving significant cost savings and power savings in short reach applications.

SFP+ DAC is a low cost alternative to traditional fiber and twisted-pair copper cabling in data center deployments. SFP+ DAC provides better cable management for high-density deployments and enhanced electrical characteristics for the most reliable signal transmission.

10GBASE-T vs 10GBASE SFP + DAC

SFP+ DAC has significantly lower overall cost when you include switch, NIC and cable, however 10GBase-T has more flexibility and can reach longer distance. For data centers, the advantages of SFP+ with DAC are a very good match for today’ s requirements and emerging trends. That’s why SFP+ DAC is being adopted rapidly as best practice for new data centers. For wiring closets, 10GBase - T will be the obvious choice once the demand for bandwidth becomes more acute and once the price and power for 10GBase-T technology comes down.

As one of the most professional optical manufacturers in China, Fiberstore’s solutions for 10 Gigabit Ethernet include 10G SFP+ direct attach fiber cable, 10G SFP+ direct attach copper cable. Besides, we also provide high-quality 10G SFP transceivers, like EX-SFP-10GE-LR, SFP-10G-LR-X, SFP-10G-SR-X, etc.

QSFP+ Optics for High-Density 40GE Connectivity

With the development of the SFF-8436 Multi Source Agreement, many vendor are now offering a variety of IEEE- and MSA-compliant Quad Small Form-Factor Pluggable Plus (QSFP+) devices for fiber networks. And there are basic three 40G QSFP+ optics for this standard: 40G LR4 QSFP+ transceiver, 40G SR4 QSFP+ transceiver and 40G LR4 parallel single mode (PSM) transceiver. This article will take a close look at these 40G QSFP+ optics for high-density 40 GE connectivity.

40G LR4 QSFP+ Transceiver

Conforming to the 802.3ba (40GBASE-LR4) standard, the 40G LR4 QSFP+ transceiver together with the LC connector can support an optical link length up to 10 kilometers over single mode fiber. For example, the following Juniper JNP-QSFP-40G-LR4 compatible 40GBASE-LR4 QSFP+ transceiver offers 4 independent transmit and receive channels, supporting link distance of 10 km over single mode fiber. In the process of transmitting, this kind of transceiver has to introduce MUX/DEMUX to multiplex/de-multiplex optical signals.

The working principle of this kind of QSFP+ transceiver is : in the transmit side, four 10 Gbp/s serial data streams are passed to laser drivers. The laser drivers control directly modulated lasers (DMLs) with wavelengths. the output of the four DMLs are optically multiplexed to a single-mode fiber through an industry-standard LC connector. In the receive side, the four 10 Gbp/s optical data streams are optically de-multiplexed by the integrated optical demultiplexer; then, each data steam is recovered by a PIN photodetector/transimpedance amplifier and passed to an output driver.

40G SR4 QSFP+ Transceiver

The 40G SR4 QSFP+ transceiver, conforming to the 802.3ba (40GBASE-SR4) standard, provides a 40G optical connection using MPO/MTP fiber ribbon connectors. Unlike the 40G LR4 QSFP+ transceiver, this kind of transceiver are used together with multi-mode fiber, supporting with a link length up to 100 meters on OM3 cable and 150 meters on OM4 cable.

The operating principle of the 40G SR4 QSFP+ Transceiver is : the transmitter convertsparallel electrical input signals into parallel optical signals through the use of a laser array. Then the parallel optical signals are transmitted parallelly through the multi-mode fiber ribbon. Reversely, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.

40G LR4 Parallel Single Mode (PSM) Transceiver

40G PSM transceivers are used to provide support for up to four 10Gb Ethernet connections on a QSFP+ port over single mode fiber. These transceivers support distance of up to 10 kilometers over single mode fiber using an 8 parallel fiber MPO interface. Each fiber pair can be broken out to a 10Gb Ethernet connection, compatible with up to four 10GBASE-LR interfaces. The MPO to 4 x LC single mode fiber patch cord can be used to breakout the 4 fiber pair of the MPO parallel connector to 4 separate fiber pairs.

Summary

To sum up, 40G SR4 QSFP+ transceivers are suitable for short-distance transmissions. So they are often used in data centers to interconnect two Ethernet switches with 12 lane ribbon OM3/OM4 cables. while 40G LR4 QSFP+ transceivers and 40G LR4 PSM transceivers are often used in long-distance transmission applications. Fiberstore offers a wide range of 40G QSFP+ transceivers, like 40GBASE-SR4, 40GBASE-LR4, 40GBASE-CR4 QSFP+ transceivers, etc. Besides, we also provide 40G direct attach cables, such as Juniper QFX-QSFP-DAC-1M, Cisco QSFP-4X10G-AOC3M and so on.

Guide to SFP+ Transceivers

Since March 1999, the Ethernet industry has been working on providing solutions to these problems by increasing the speed of Ethernet from 1 to 10 gigabits per second. For enterprise LAN applications, 10 Gigabit Ethernet enables network managers to scale their Ethernet networks from 10 Mbps to 10,000 Mbps, while leveraging their investments in Ethernet as they increase their network performance. Meanwhile, the newest module standard, namely the enhanced small form-factor pluggable (SFP+) transceiver , has been developed to meet the increasing usage and demand for higher-performance servers, storage and interconnects in the 10 Gigabit Ethernet world.

What Is the SFP+

The small form-factor pluggable plus (SFP+) can be referred to as an enhanced version of the SFP that supports data rates up to 16 Gbit/s. The SFP+ specification was first published on May 9, 2006, and version 4.1 published on July 6, 2009. SFP+ supports 8Gbit/s Fiber Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors. The SFP+ product family includes cages, connectors, and copper cable assemblies. The SFP+ transceiver modules are specified for 8Gbps/10Gbps/16Gbps Fiber Channel and 10-Gigabit Ethernet applications.

Advantages of SFP+ Transceivers

SFP+ transceiver comes with various outstanding advantages. SFP+ covers various data rates for different communication standards like Ethernet, SONET (OC-192), SDH (STM-64) or 10G Fiber Channel and any other interfaces with a data rate up to 16 Gbps. It is with more compact size and measurement than former X2, Xenpak and XFP, which enables SFP+ suitable for installations with higher port density. In addition, SFP+ takes the advantage of lower power consumption for less than 1W, like 455883-B21 compatible 10GBASE-SR SFP+ transceiver shown in the following picture. SFP+ transceivers are with managed digital optical monitoring and superior high temperature performance. Therefore, it is a cost effective way to connect a single network device to a wide variety of fiber cable distances and types using a SFP+ transceiver module.

Applications of SFP + Transceivers

SFP+ transceivers are designed to use together with small form factor connectors and offer high speed and physical compactness, providing instant fiber connectivity for your networking gear. They are available for copper and for all common fiber modes, wavelengths and data rates and allow network operators to connect different interface types to the same network equipment, via an SFP+ port. To take advantage of this flexibility and to save money, more and more network equipment are being designed with SFP/SFP+ ports. Several industrial acknowledged standards for SFP+ have been made for 10Gpbs networks, including 10Gbase-SR which defines the SFP+ transceiver working with OM3 10G multimode fiber at 30 to 300 meters range, 10Gbase-LR which defines the SFP-10G-LR transceiver working with single mode fiber at 10km range, and so on.

To conclude, 10 Gigabit Ethernet has become the technology of choice for enterprise, metropolitan, and wide area networks. In terms of physical media, the 10G SFP+ transceiver can support distances to 300 meters on multimode fiber and 40 km or more on single mode fiber. Fiberstore is a leading supplier of SFP+ transceivers. We have a large selection of SFP+ transceivers in stock, such us SFP+ MM 300m, SFP+ 10km, SFP+ 40km, SFP+ 80km, CWDM SFP+, DWDM SFP+, BiDi SFP+, etc. All of our SFP+ transceivers are tested in-house prior to shipping to ensure that they will arrive in perfect physical and working condition.

FAQ About OM4 Fiber

The explosion in demand for bandwidth in enterprise networks is driving an urgent need for higher Ethernet network speeds. Increasingly, these higher bandwidth system requirements have dictated a need to transition from cost-effective multi-mode systems to more costly single-mode systems. Until OM4 was formally specified, many 40G and 100G applications would have had to make the leap to single-mode system solutions. OM4 effectively provides an additional layer of performance that supports these applications at longer distances.

What is “OM4” fiber?

OM4 is a laser-optimized, high bandwidth 50 micrometer multimode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for this grade of optical fiber. It can be used to enhance the system cost benefits enabled by 850 nm VCSELs for the earlier 1 G and 10 Gb/s applications as well as the 40 and 100 Gb/s systems. For example, Fibestore's Push-Pull MPO patch cable is manufactured using laser-optimized, 50/125, OM4 multimode cable, and supports speeds up to 100GbE. OM4 fiber can support Ethernet, Fibre Channel, and OIF applications, allowing extended reach upwards of 550 meters at 10 Gb/s for ultra long building backbones and medium length campus backbones. OM4 fiber is also especially well suited for shorter reach data center and high performance computing applications.

What are the standards that define the use of OM4 fiber?

There are a number of standards under development that will define the use of OM4 fiber for high-speed transmission. Within the TIA, work is progressing on TIA-492AAAD, which will contain the OM4 fiber performance specifications. Similarly, IEC is working in parallel to adopt equivalent specs that is documented in the international fiber standard IEC 60793-2-10.

What bandwidth does the standard specify for OM4 fiber?

As of this writing, there is general agreement among the standards committees that OM4 has a significantly higher bandwidth (EMB of 4700 MHz-km with VCSEL launch at 850 nm) than OM3. It is also backward compatible with applications calling for OFL bandwidth of at least 500 MHz-km at 1300 nm (e.g. FDDI, IEEE 100BASE-FX, 1000BASE-LX, 10GBASE-LX4, and 10GBASE-LRM). There was some discussion and debate within the standards groups about a minimum OFL bandwidth requirement at 850 nm. It has been shown that fibers with higher OFL bandwidth can perform better with VCSELs that launch more power into outer modes. That is why the existing OM3 fiber standards require a minimum 1500 MHz-km OFL bandwidth at 850 nm.

What’s the difference between OM3 and OM4?

It is important to note that OM4 glass is not necessarily designed to be a replacement for OM3. Despite the relatively long-standing availability of OM4, there are no plans to obsolete OM3 fiber optic cabling. For most systems, OM3 glass is sufficient to cover the bandwidth needs at the distances of the current installation base. Most system requirements can still be reliably and cost effectively achieved with OM3, and this glass type will remain available for the foreseeable future. Despite the availability of OM4 glass, OM3 is quite capable of 40 and 100 Gb/s applications albeit at significantly shorter distances than OM4. For instance, Cisco QSFP-40G-CSR4 compatible transceiver from Fiberstore can reach 300m and 400m, respectively over OM3 and OM4 cables.

A variety of cable configurations are available utilizing the OM4 fiber for in-building and inter-building applications including the following types: distribution, breakout, interconnect, loose tube and industrial armored. All of Fiberstore’s OM4 cable assemblies are with high quality and competitive prices. They are assembled and 100% optically tested in the factory prior to shipment.