# How to Understand Tx Power and Rx Power of a Fiber Transceiver?

As we all know, single mode fiber optic transceiver is designed for long distance data transmission and multimode fiber optic transceiver is for short distance link. How to calculate the specific distance that a fiber optic transceiver can support at a certain occasion? What factors are crucial to the transmission distance? Do you have any idea of Tx (transmit) power and Rx (receive) power level of a fiber optic transceiver? This article will show you by introducing 10GBASE-SR SFP+ and 10GBASE-LR SFP module.

Tx Power and Rx Power of a Fiber Transceiver

First, let’s understand the most two important factors of the fiber optic transceiver: Tx power and Rx power. The optical Tx power is the signal level leaving that device and it should be within the transmitter power range. The Rx power is the incoming signal level being received from the far end device and it should fall within the receive power range.

10GBASE-SR SFP+ is a multimode fiber transceiver and can support the distance of 300 m over OM3 multimode fiber patch cable. While 10GBASE-LR SFP module is a single mode type and can run the network distance up to 10 km over single mode fiber patch cords. Before purchasing 10GBASE SFP+ module, you must carefully read the product details. The following lists the product details about 10GBASE-SR SFP+ and 10GBASE-LR SFP module from Fiberstore. As showing below, Tx power of this Cisco compatible 10GBASE-SR SFP+ is between -7.3 dB and 1 dB. The maximum receive power is below -11.1 dB. With regard to Cisco compatible 10GBASE-LR SFP module, Tx power is from -8.2 to 0.5 dB and the maximum Rx power is -14.4 dB

Tx Power and Rx Power of 10GBASE-SR SFP+

Tx Power and Rx Power of 10GBASE-LR SFP+ Module
Tx Power and Rx Power VS. Optical Power Budget

To calculate the specific distance of a fiber optic transceiver, we need to know its optical power budget (maximum allowable loss).

Optical power budget = Tx power – Rx power

Therefore, according to the Tx power and Rx power, we can calculate the maximum allowable loss of 10GBASE-SR SFP+ and 10GBASE-LR SFP module.

Optical Power Budget of 10GBASE-SR SFP+

Min Tx Power = -7.3 dB
Max Rx Power = -11.1 dB
Optical power budget (maximum allowable loss) = (-9.5 dB) – (-11.1 dB)=1.6 dB

Optical Power Budget of 10GBASE-LR SFP+ Module

Min Tx Power = -8.2dB
Max Rx Power = -14.4 dB
Optical power budget (maximum allowable loss) = (-8.2 dB) – (-14.4 dB)=6.2 dB

Tx Power and Rx Power VS. Transmission Distance

Except optical power budget, we have to consider other factors including the link length, fiber optical connectivity components, fusion splicing points and some unpredictable fiber attenuation caused by fiber patch cable bending (usually the attenuation is about 3 dB). The loss of each connector is 0.6 dB and 0.1 dB of each fusion splicing point. Suppose we use 10GBASE-LR SFP+ module to build a network covering 2 connectors, 4 fusion splicing points. This module is interfaced with LC single mode fiber patch cord. If the single mode fiber cable has the wavelength of 1310 nm, the cable loss is about 0.35 dB per kilometer.

The worst optical loss = Power Budget – Total Optical Power Loss=6.2 dB – 1.2dB (2×0.6 dB) – 0.4dB (0.1×4) – 3dB (safety factor) = 1.6 dB
Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/km]=1.6dB/0.35dB/km
So we can get 10GBASE-LR SFP+ module can support at least 4.57 km at this occasion. Data transmission distance is mainly influenced by the optical power budget and fiber cable loss. From the above content, the optical power budget of 10GBASE-SR SFP+ is smaller than that of 10GBASE-LR SFP+ module. The more the optical power budget, the further the fiber transceiver can support. What’s more, the cable loss of multimode fiber cable is larger than that of single mode fiber cable. Obviously 10GBASE-LR SFP+ module can support longer link distance than 10GBASE-SR SFP+.

Note: The optical power budget is based on a theoretical calculation, and is just for reference. The transmission distance should be calculated based on the power budget of fiber transceiver module tested on the switch and some practical attenuation.

Conclusion

Tx power and Rx power level of a transceiver are the main factors of transmission distance. The more the optical power budget, the better the transceiver. Before purchasing a transceiver, you’d better calculate the optical power budget according to transceiver module details.

Originally published at http://www.fiber-optic-equipment.com

# Why not Use Third-party Fiber Transceivers for Your Ubiquiti Switches?

Ubiquiti is famous for its switches such as Edge Switch, Edge Router, UniFi switch. Last year, this manufacturer officially released its own SFP and SFP+ fiber optic transceivers which are compatible with their switches. At the same time, it’s said that fiber transceivers from some fiber optic transceiver manufacturers such as Fiberstore can support Ubiquiti switches. This article will discuss what kind of third-party fiber transceivers are compatible with Ubiquiti switches and which fiber optic transceiver manufacturers is the most reliable.

Ubiquiti Fiber Transceivers

Ubiquiti switches are specially designed for 1G and 10G network. They didn’t produce their own fiber transceivers until last year. They only provide a small amount of single mode and multimode fiber transceivers. UF-MM-1G and UF-SM-1G-S are designed for SFP ports on Ubiquiti switches. And fiber transceivers like UF-MM-10G, UF-SM-10G, UF-SM-10G-S are for Ubiquiti switches’ SFP+ ports.

Third-party Fiber Transceivers For Ubiquiti Switches

Except their own SFP or SFP+ transceivers, those from other fiber optic transceiver manufacturers like Cisco, Dell, HP, Finisar, Brocade have been tested to be compatible with Ubiquiti switches by some users. Cisco, the world famous fiber optic transceiver manufacturer, has seven SFPs supporting Ubiquiti switches, Cisco GLC-LH-SM 30-1299-01 SFP, Cisco GLC-SX-MM, Cisco GLC-SX-MM 1000BASE-SX SFP, Cisco SFP-H10GB-CU1M, Cisco MGBSX1 Gigabit SX Mini-GBIC SFP Transceiver and Cisco GLC-T. Besides, for 10G network, Cisco SFP-10G-SR can be plugged in SFP+ ports on their switches.

Fiberstore Fiber Transceivers For Ubiquiti Switches

Fiberstore also has a wide variety of SFP and SFP+ transceivers compatible for Ubiquiti switches. Users have recommended some SFPs and SFP+s from Fiberstore, for instance, SFP1G-LX-31 1310nm (single mode SFPs), SFP-1G85-5M (multi-mode), SFP-GB-GE-T Module, SFP-10G85-3M (multi-mode).

Comparison Between Ubiquiti and Fiberstore Fiber Transceiver

There are so many third-party transceiver manufacturers providing compatible fiber transceivers fro Ubiquiti switches. But which fiber transceiver supplier should you choose? The answer is Fiberstore. Now let’s see why Fiberstore is more advantageous by comparing Ubiquiti with Fiberstore fiber transceiver.

• Fiber Transceiver Category—Ubiquiti has only one single mode SFP and one multimode SFP. As to SFP+ transceivers, there only two single mode modules and one multimode module. The fiber transceiver category is very limited. While users have plenty of choices for SFPs and SFP+s from Fiberstore. As mentioned above, Ubiquiti switches support some fiber transceivers from third-party fiber optic transceiver manufacturers. Fiberstore offers many compatible brands like Cisco, Dell, HP, Finisar, Brocade, etc. Those SFPs and SFP+s have been tested to be suitable for Ubiquiti switches.
• Fiber Transceiver Quality—Some fiber optic transceiver manufacturers produce SFP and SFP+ transceivers with low price. However, the quality of those fiber transceivers can’t be assured. In our test center, we have switches from Cisco, Dell, Extreme, Juniper and other famous brands. Every fiber transceiver offered by Fiberstore before shipping has to go through strict test to assure 100% compatibility and high performance.

• Fiber Transceiver Price—Except fiber transceiver quality, fiber transceiver price is another important factor to be considered. Compare fiber transceiver price of Fiberstore with that of other fiber optic transceiver manufacturers, it’s obvious that Fiberstore has more advantages. That’s one of the reasons why Fiberstore wins popularity among customers. You can check the following screenshots about the the feedback from customers.

Conclusion

Originaly published at http://www.fiber-optic-equipment.com

# QSFP+ to 4xSFP+ AOC and QSFP+ MTP Breakout Cable Solution

Migration from 10G to 40G is an inevitable trend in data center. Migration means you need new QSFP+ transceiver modules, fiber patch cables and other equipment. Common two methods to migrate from 10G to 40G for short distance are QSFP+ to 4xSFP+ AOC and QSFP+ MTP breakout cable solution. When you come across this issue, it’s hard to tell which one is better. This article will introduce their difference and tell you how to make the right decision.

40G QSFP+ to 4xSFP+ AOC

40G QSFP+ to 4xSFP+ AOC (active optical cable) is composed of a QSFP+ connector on one side and four individual SFP+ connectors on the other side. The QSFP+ connector (40Gbps rate) offers four parallel, bidirectional channels and each operates at up to 10.3125 Gbps. The QSFP+ connector can be installed into QSFP+ port on the switch and feed up to four 10G SFP+ links. And the link lengths can reach 100 meters on OM3 fiber. It’s a cost-effective interconnect solution for 40G and 10G switches and servers.

QSFP+ MTP Breakout Cable

The other common solution for 10G to 40G short distance migration is to use breakout cable and of course corresponding transceivers. How to achieve the connection? You’re gonna need 40GBASE-SR4 QSFP+, MTP to LC breakout cable and 10GBASE-SR SFP+. Here we are going to explain 40GBASE-SR4 QSFP+ and MTP-LC breakout cable in details.

First, 40GBASE-SR4 QSFP+ is designed for 40 Gigabit data center and can support the link length of 100 m and 150 m respectively on laser optimized OM3 and OM4 fiber cables. This module offers 4 independent channels for transmitting and receiving. Each lane is capable of running 10Gbps signal and is compliant to IEEE 10GBASE-SR specification. Connecting with 12-fiber MTP/MPO cables, it can support 40Gbps network. Or combine 40GBASE-SR4 QSFP+ with 4x10G breakout cable and send data to four 10GBASE-SR SFP+.

Second, MTP to LC breakout cable is suitable for high density network. It’s specifically designed for fast Ethernet, fiber channel, data center and gigabit Ethernet application. QSFP+ MTP to LC breakout cable is used for a direct connection between QSFP+ to 4xSFP+ ports with no patch panels or intermediate trunks in between. On one side, it’s an MTP connector with 8 or 12 fibers. On the other side, there are 4 duplex LC connectors. Each fiber cable transmits 10Gbps.

Differences of Two Solutions

Two methods of 10G to 40G migration over short distance have been introduced in above content. Comparing the two different solutions, you can find some obvious differences. The following lists some points for your convenience to make suitable decision.

• Price—The second solution needs at one QSFP+, 4 SFP+ and an MTP-LC breakout cable. The price of these devices is higher than 40G QSFP+ to 4xSFP+ AOC. So 40G QSFP+ to 4xSFP+ AOC is cheaper.
• Complexity—The second solution seems more complicated since it needs more optical equipment. You need to order and manage cables.
• Distance—40G QSFP+ to 4xSFP+ AOC can only support the distance up to 100 m. While using MTP-LC breakout cable, the link distance can reach 150 m over OM4 cable.
Conclusion

You must have a full understanding of these two solutions. 40G QSFP+ to 4xSFP+ AOC is easier and cheaper than MTP to LC breakout cable. If you’re a new technician and have tight budget, you can buy AOC cable. But if you don’t care too much about money, you can select 40GBASE-SR4 QSFP+ and MTP to LC breakout cable to get a little longer link length. Hope this article can help you make the right decision.

Originaly published at http://www.fiber-optic-equipment.com

# What Distance Can 100G QSFP28 Transceiver Support?

The rapid growing bandwidth keeps driving the need for 100G transceivers to build data centers, enterprise, long-haul networks. Just as 1G, 10G optical modules, 100G QSFP28 transceivers also have single-mode and multimode categories to support short and long distance network links. So what kind of 100G QSFP28 transceivers are included? What distance can each 100G QSFP28 support?

100G QSFP28–Supported Distance Below 1km

Multimode 100G QSFP28 modules are used for short distance applications, such as QSFP28 Cisco QSFP-100G-SR4-S 100GBASE-SR4 transceiver. It provides 100GBASE-SR throughput at a wavelength of 850 nm by connecting with multimode MTP/MPO cable. It can support the link lengths up to 70 m over OM3 MPO fiber patch cable and 100 m over OM4 MPO fiber jumpers.

But there is a special 100G QSFP28 transceiver–QSFP-100G-PSM4-S. This QSFP28 is a single-mode transceiver. It carries 100G data over 12-fiber single-mode MPO fiber patch cords. However, the maximum link lengths it can support is only 500 meters.

100G QSFP28–Supported Distance From 1km-10km

To support long distance signal transmission, single-mode transceivers are generally selected. The following will list some 100G QSFP28 modules which can reach the link distance from 1 km to 10 km.

QSFP28 100GBASE-CWDM4. This transceiver applies WDM multiplexing and demultiplexing technique and carries 100G Gigabit Ethernet signal over four wavelengths. Different from the above two 100G QSFP28 optics, it’s configured with duplex LC interfaces. With QSFP28 100GBASE-CWDM4 modules, you can build networks with link lengths up to 2 km over single-mode duplex LC patch cords.

QSFP28 100GBASE-LR4. This hot-pluggable 100G QSFP28 form factor can support 103.1Gbps data rate. It’s compliant with the QSFP28 MSA and IEEE802.3ba 100GBASE-LR4. The 100G data is transmitted over four wavelengths. Because of multiplexing and demultiplexing within this QSFP28 transceiver, it matches duplex LC patch cords. And it can support links up to 10 km over single-mode LC fiber cable.

100G QSFP28–Supported Distance Over 10km

In fact, 10km link lengths of 100G can’t meet users’ demands. So 100G QSFP28 which can support over 10km lengths are needed to build long-haul network. Due to the optic package size and the maximum power, the distance supported by 100G QSFP28 transceivers are restricted. Vendors are required to research and develop optics that allow for existing high power components and devices to consume lower power in a smaller space. It’s said there are 100G QSFP28 ER4 and 100G QSFP28 ZR4 transceivers in the market. Each can support the maximum network link lengths up to 30 km and 80 km. But consumers can’t easily get those 100G QSFP28 modules. But we believe that ER4 and ZR4 technology will be available in the market sooner or later.

At present, if your switch ports are QSFP28 and you need to build 100G network links over 10km, you are suggested to apply amplification technology. The other method is 100G CFP ER4 that support 40km link lengths. Of course your switch port should be CFP or you can find a device to convert QSFP28 to CFP.

Conclusion

Now people can get 100G QSFP28 transceivers for link lengths up to 10 km. Yet not too many transceiver vendors have enough stocks. In the Internet era, what is important is the speed. Thus, seek for reliable vendors who have huge stocks of 100G QSFP28 like FS.COM. And we will release 100G QSFP28 ER4 and 100G QSFP28 ZR4 in the future to support longer distances.

Originally published at http://www.fiber-optic-equipment.com

# Does Multimode SFP Work Over Single-mode Fiber Cable?

When you prepare to connect some SFPs with fiber patch cords, you may find SFPs are multimode modules while your fiber cables are single-mode. Try to connect those optics to fiber cable, but no green light and the link fails. So multimode SFPs can’t work over single-mode fiber cables. To avoid the wasting of time and money, you should better know well about single-mode and multimode SFPs and fiber patch cords.

Single-mode and Multimode SFP

SFP, small form factor pluggable transceiver, can support the data rate up to 1Gbps. SFPs can be divided into single-mode and multimode modules.

For single-mode SFPs, there are “LX” for 1310 nm and “EX” “EZX” for 1550 nm. Single-mode SFPs are designed to transmit signals over long distances. For example, Cisco GLC-LH-SM-15 compatible 1000BASE-LX/LH SFP 1310nm 15km DOM transceiver, main product information is shown as follows:

• Wavelength: 1310 nm
• Interface: LC duplex
• Max Cable Distance: 15 km
• Max Data Rate: 1000Mbps
• Cable Type: SMF

Comparatively, multimode SFPs are identified with “SX”. This kind of optics is specially for short distance data transmission. For instance, Cisco GLC-SX-MM compatible 1000BASE-SX SFP 850nm 550m transceiver, this is a typical multimode SFP.

• Wavelength: 850 nm
• Interface: LC duplex
• Max Cable Distance: 550m over OM2 MMF
• Max Data Rate: 1000Mbps
• Cable Type: MMF

Single-mode Fiber Cable and Multimode Fiber Cable

Fiber patch cables are used to connect transceivers on your switch/device. You have to buy the right fiber cable type for your optics. Fiber cable has two different categories: single-mode and multimode.

Generally, single-mode fiber cable can support further distance because of lower attenuation, but the price is higher. While multimode fiber cable has a larger core, usually multimode fiber cable is constructed in 50/125 and 62.5/125. It allows multiple modes of light to propagate. When the light passes through the core, the light reflections increases and more data can be transmitted at given time. As the high dispersion during signal transmission, the link distance gets reduced. So multimode fiber cable is for short distance application. Multimode fiber cable is a little more complex than single-mode fiber cable since it includes four different types of OM1, OM2, OM3, OM4. OM1 and OM2 fiber patch cable can support the data rate up to 10Gbps. OM3 and OM4 are laser optimized so that they can be used in high density data center to support the data rate of 40Gbps and 100Gbps. The following table shows how long each kind of fiber cable can reach running at different data rate.

 Fiber Mode Cable Type 1GbE 10GbE 40GbE 100GbE Single-mode OS2 100km 40km 40km 40km Multimode OM1 275m(SX) 33m(SR) / / OM2 550m(SX) 82m(SR) / / OM3 550m(SX) 300m(SR) 100m 100m OM4 1000m(SX) 400m(SR) 150m 150m

Note: “SR” implies multimode 10Gpbs SFP+.

What Is Single Mode Fiber?
What Are OM1, OM2, OM3 and OM4?
Solutions for Multimode SFP

If you have Cisco Catalyst 3650 WS-C3650-48PS switches with 4x1G uplink ports, to build a 300m-network link, you are gonna purchase fiber patch cable and SFP modules. What kind of optical equipment should you choose?

As to the SFP module, you need Cisco GLC-SX-MM 1000BASE-SX SFP. Or you can spend less money on third-party SFPs with 100% compatibility. Next step, you need to find suitable fiber patch cable to match this type of SFP. Since 1000BASE-SX SFP is multimode, of course you need multimode fiber cable. Considering the distance of 300 meters, OM1 can only reach 275 meters. So OM2 is the best choice for it’s the cheapest and can reach 550 meters.

Conclusion

It’s obvious that multimode SFPs can’t work over single-mode fiber cables. When buying SFPs, watch the standards on the label carefully and find if it’s “SX” or “LX”, “EX”. If it shows “SX”, then find multimode fiber patch cable. It’s not very difficult to choose right cable for your SFP modules.

Originally published at http://www.fiber-optic-equipment.com

# Tips for Fiber Cable Installation You Should Know

Fiber cable installation is not an easy task for most of us. It’s thought as the job of professional engineers since special training is needed during the complicated process. But it would be better if you know knowledge of fiber cable installation in case that you need to run fiber cable in your home or business. This article is going to offer you some tips for fiber cable installation.

Before Fiber Cable Installation

Before starting fiber cable installation, please make sure there is fiber optic service in your area. If it’s available, find the nearest distribution box. What you need to do is to run fiber cable from the box to your house.

A considerate plan is the first step of successful fiber cable installation. Carefully design the cabling route. It would be better if you mark where the cable goes, into the walls, or underground, or through conduit… Point out all the termination points and splice points. At the same time, write down any potential problems you may come across during the installation. A good plan is also beneficial to avoid fiber cable waste.

Once finish the plan, you’re going to buy fiber optic cable for your applications. Except fiber optic cable, you need tools for cable management & installation, fiber splicing and fiber testing. So make a shopping list for your fiber cable installation. Then select a reliable fiber cable supplier who can meet the requirements of both high quality and low cost.

During Fiber Cable Installation
What You Should Do

Leave spare cable length—Each fiber cable for installation should be a few inches longer than the plan says. Because you can’t make sure everything goes as you wish. So you should leave plenty of spare fiber cables when beginning cable installation work.

Avoid electrical interference—Though fiber cable is not as vulnerable to electrical noise as copper cables, some devices, such as the boxes for fluorescent lights, may cause interference. So keep your fiber cable three or more feet from those devices.

Avoid end face contamination—The tip of fiber optic connector can be easily contaminated or damaged. So leave protective caps on until you are ready to plug into the equipment. Don’t forget to inspecting the end face before plugging in. If there is any contaminate, clean it.

Fiber network testing—Test each section of your fiber optic network. That’s easy to discover the problem and troubleshoot it. Don’t do this work until you finish the entire cable installation. In that situation, it’s hard to find out the trouble if the network fails.

What You Should Not Do

Don’t bend fiber cables. Fiber optic cables perform the best when it is running straight. But during installation in reality, sometimes bending can’t be avoided. Cables from different vendors may have different standards of bend radius. Or you can buy bend insensitive fiber cable for better performance.

Don’t pull too hard on the cable. Properly pull the fiber cable to avoid bending or snagging through the conduit or underground. However, don’t pull it too hard especially when the fiber cable is too short. Otherwise, it would ruin the cable or fiber optic connector.

Don’t mix and match different core sizes. Fiber optic cables are typically color coded. From the outside cable jacket, you can get information about fiber core sizes. To know more about fiber cable jacket, you can visit my last blog What Can We Get From Fiber Cable Jacket?

Don’t pinch the fiber cable. Pinch the fiber cable can squeeze the fiber and affect link performance. When use zip-ties, pay attention to this point.

Conclusion

Once you finish fiber cable installation, you can enjoy fiber optic network. See, fiber cable installation is not as tough as you think. Follow these tips mentioned above when you run cables for your house, you can keep away from most bothering issues.

Originally published at http://www.fiber-optic-equipment.com

# What Can We Get From Fiber Cable Jacket?

Fiber optic cable is applied as the most advanced communication medium by more and more users. Compared with copper cable, it can support more and better optical signal transmission of voice, data, video, etc. and offer many other advantages. When purchasing fiber optic cables, you must see the cable jacket at first. So what information does the outside jacket tell? What type of cable jacket should you select? Come with me to find the secrets of fiber cable jacket.

Fiber Cable Jacket Introduction

Fiber optic cable is constructed very complicated from the inside core, cladding, coating, strengthen fibers to the outside cable jacket. The core made of plastic or glass is the physical medium for optical signal transmission. As bare fiber can be easily broken, cable outer jacket is needed for fiber protection. The cable jacket is the first line of moisture, mechanical, flame and chemical defense for a cable. Without the jacket, fiber optic cables are very likely to be damaged during and after installation.

Fiber Cable Jacket Characteristics

In most situations, robust cable jacket is better because the environment above or underground may be harsh. For better applications, you’d better take cable jacket seriously. Cable jacket is not as easy as you think. There are many characteristics you need to consider. Except the flexibility, it should withstand very low and high temperature. Whether the cable jacket has the good features of chemical and flame resistance. All these characteristics depend on cable jacket materials.

Fiber Cable Jacket Materials

Cable jacket is made of various types of materials. As mentioned above, the cable jacket should stand the test of different environmental conditions, including the harsh temperature, the sun & the rain, chemicals, abrasion, and so on. The following shows several common cable jacket materials for your reference.

PE (Polyethylene)—PE is the standard jacket material for outdoor fiber optic cables. It has excellent properties of moisture and weather resistance. It also has the good electrical properties over a wide temperature range. Besides, it’s abrasion resistant.

PVC (Polyvinyl Chloride )—PVC is flexible and fire-retardant. It can be used as the jacket materials for both indoor and outdoor cables. PVC is more expensive than PE.

LSZH (Low Smoke Zero Halogen)—LSZH jacket is free of halogenated materials which can be transformed into toxic and corrosive matte during combustion. LSZH materials are used to make a special cable called LSZH cable. LSZH cables produce little smoke and no toxic halogen compounds when these cables catch fire. Based on the benefits, LSZH cable is a good choice for inner installations.

Fiber Cable Jacket Color

Fiber cable jacket color depends on the fiber cable type. Fiber cable includes single-mode and multimode types. For single-mode fiber cable (Blog about single-mode fiber cable please read my blog What Are OM1, OM2, OM3 and OM4?), the jacket color is typically yellow. While for multimode cable ( more details on multimode fiber cable ), the jacket color can be orange (OM1&OM2 cable), aqua (OM3 cable) and purple (OM4 cable). For outside plant cables, the jacket color is black.

How to Choose Fiber Cables?