Tag Archives: SFP

The Basics of 1000BASE-SX and 1000BASE-LX SFP

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Gigabit Ethernet has been regarded as a huge breakthrough of telecom industry by offering speeds of up to 100Mbps. Gigabit Ethernet is a standard for transmitting Ethernet frames at a rate of a gigabit per second. There are five physical layer standards for Gigabit Ethernet using optical fiber (1000BASE-X), twisted pair cable (1000BASE-T), or shielded balanced copper cable (1000BASE-CX). 1000BASE-LX and 1000BASE-SX SFP are two common types of optical transceiver modules in the market. Today’s topic will be a brief introduction to 1000BASE-LX and 1000BASE-SX SFP transceivers.

1000BASE in these terms refers to a Gigabit Ethernet connection that uses the unfiltered cable for transmission. “X” means 4B/5B block coding for Fast Ethernet or 8B/10B block coding for Gigabit Ethernet. “L” means long-range single- or multi-mode optical cable (100 m to 10 km). “S” means short-range multi-mode optical cable (less than 100 m).

1000BASE-SX
1000BASE-SX is a fiber optic Gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer, near infrared (NIR) light wavelength. The standard specifies a distance capability between 220 meters and 550 meters. In practice, with good quality fiber, optics, and terminations, 1000BASE-SX will usually work over significantly longer distances. This standard is highly popular for intra-building links in large office buildings, co-location facilities and carrier neutral internet exchanges. 1000BASE-SX SFP works at 850nm wavelength and used only for the purposed of the multimode optical fiber with an LC connector. 1000BASE-SX SFP traditional 50 microns of multimode optical fiber link is 550 meters high and 62.5 micron fiber distributed data interface (FDDI) multimode optical fiber is up to 220 meters. Take EX-SFP-1GE-SX as an example, this SX fiber transceiver supports DOM function and the maximum distance of the SX SFP is 550 m. The 1000Base-SX standard supports the multimode fiber distances shown in table 1.

1000Base-SX standard

1000BASE-LX
Specified in IEEE 802.3 Clause 38, 1000BASE-LX is a type of standard for implementing Gigabit Ethernet networks. The “LX” in 1000BASE-LX stands for long wavelength, indicating that this version of Gigabit Ethernet is intended for use with long-wavelength transmissions (1270–1355 nm) over long cable runs of fiber optic cabling. 1000BASE-LX can run over both single mode fiber and multimode fiber with a distance of up to 5 km and 550 m, respectively. For link distances greater than 300 m, the use of a special launch conditioning patch cord may be required. 1000BASE-LX is intended mainly for connecting high-speed hubs, Ethernet switches, and routers together in different wiring closets or buildings using long cabling runs, and developed to support longer-length multimode building fiber backbones and single-mode campus backbones. E1MG-LX-OM is Brocade 1000BASE-LX SFP, this LX single-mode transceiver  operates over a wavelength of 1310nm for 10 km.

1000BASE-LX SFP

Difference Between LX, LH and LX/LH
Many vendors use both LH and LX/LH for certain SFP modules, this SFP type is similar with the other SFPs in basic working principle and size. However, LH and LX/LH aren’t a Gigabit Ethernet standard and are compatible with 1000BASE-LX standard. 1000BASE-LH SFP operates a distance up to 70km over single-mode fiber. For example, Cisco MGBLH1 1000BASE-LH SFP covers a link length of 40km that make itself perfect for long-reach application. 1000BASE-LX/LH SFP can operate on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers. In addition, when used over legacy multimode fiber type, the transmitter should be coupled through a mode conditioning patch cable.

Conclusion
1000BASE SFP transceiver is the most commonly used component for Gigabit Ethernet application. With so many types available in the market, careful notice should be given to the range of differences, both in distance and price of multimode and single-mode fiber optics. Fiberstore offers a large amount of in-stock 1000BASE SFP transceivers which are compatible for Cisco, Juniper, Dell, Finisar, Brocade, or Netgear in various options. If you have any requirement of our products, please send your request to us.

Related Article: Can We Interconnect SFP, SFP+, XFP, X2 and XENPAK?

Related Article: How Many Types of SFP Transceivers Do You Know

Common Mistakes in Fiber Optic Network Installation

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When install a fiber optic network, people may make some common mistakes, which were usually overlooked. In this article, I will list the most common ones. Hope to give you some guidance for your optical network installation.

1. Single Strand Fiber Device Must Be Used in Pairs

You will never buy two left shoes, but people often make a similar mistake when they’re working with Single Strand Fiber (SSF). Single strand fiber technology allows for the use of two independent wavelengths, such as 1310 and 1550 nm, on the same piece of cable. The most common single strand fiber device is Bi-Directional (BiDi) transceiver. Two BiDi transceiver must be matched correctly. One unit must be a 1310nm-TX/1550nm-RX transceiver (transmitting at 1310 nm, receiving at 1550 nm) and the other must be a 1550nm-TX/1310nm-RX transceiver (transmitting at 1550 nm, receiving at 1310 nm). The 1550nm-TX/1310nm-RX transceiver is more expensive than the 1310nm-TX/1550nm-RX transceiver, due to the cost of their more powerful lasers. So network engineers may hope to save money by installing a pair of 1310nm-TX/1550nm-RX transceivers. But, like mismatched shoes, it doesn’t work.

single-strand-fiber

2. Don’t Use Single-Mode Fiber over Multimode Fiber

Some people may want to make use of legacy cabling or equipment from an older fiber installation to save cost. But keep in mind that single-mode and multimode fiber are usually incompatible. Multimode fiber uses cable with a relatively large core size, typically 62.5 microns (om2, om3 and om4), and 50 microns (om1) still used in some installations. The larger core size simplifies connections and allows for the use of less powerful, less expensive light sources.  But the light therefore tends to bounce around inside the core, which increases the modal dispersion. That limits multimode’s useful range to about 2 km. Single-mode fiber combines powerful lasers and cabling with a narrow core size of 9/125 microns to keep the light focused.  It has a range of up to 120 km, but it is also more expensive. If you tried to use single-mode fiber over a multimode fiber run.  The core size of the fiber cable would be far too large.  You’d get dropped packets and CRC errors.

single-mode-multimode-fiber

3. Understand All kinds of Fiber connectors First

Fiber optic transceivers use a variety of connectors, so make clear their differences before you begin ordering products for a fiber installation is necessary. SC (stick and click) is a square connector. ST (stick and twist) is a round, bayonet-type. LC, or the “Lucent Connector”, was developed by Lucent Technologies to address complaints that ST and SC were too bulky and too easy to dislodge. LC connectors look like a compact version of the SC connector. SFP (small form‐factor pluggable) transceivers usually use LC connector.  Less common connectors include MT-RJ and E2000.

st-lc-sc

4.Connector Links and Splice Times Also Affect 

Although single-mode fiber suffers from less signal loss per km than multimode, all fiber performance is affected by connectors and splices. The signal loss at a single connector or splice may seem insignificant. But as connectors and splices become more numerous signal loss will steadily increase. Typical loss factors would include 0.75 dB per connector, 1 dB per splice, 0.4 dB attenuation per km for single-mode fiber and 3.5 dB attenuation per km for multimode fiber.  Add a 3 dB margin for safety. The more splices and connectors you have in a segment, the greater the loss on the line.

5. Don’t Use APC connector with UPC Connector

Fiber connections may use Angle Polished Connectors (APC) or Ultra Polished Connectors (UPC), and they are not interchangeable. There are physical differences in the ferules at the end of the terminated fiber within the cable (shown in the figure below).  An APC ferrule end-face is polished at an 8° angle, while the UPC is polished at a 0° angle. If the angles are different, some of the light will fail to propagate, becoming connector or splice loss. UPC connectors are common in Ethernet network equipment like media converters, serial devices and fiber‐based switches. APC connectors are typical for FTTX and PON connections.  ISPs are increasingly using APC.

apc-upc-connector

6. Don’t Connect SFP to SFP+ Transceivers

Small Form Pluggable (SFP) transceivers are more expensive than fixed transceivers.  But they are hot swappable and their small form factor gives them additional flexibility. They’ll work with cages designed for any fiber type and their prices are steadily dropping.  So they have become very popular. Standard SFPs typically support speeds of 100 Mbps or 1 Gbps. XFP and SFP+ support 10 Gbps connections. SFP+ is smaller than XFP and allows for greater port density.  Though the size of SFP and SFP+ is the same, you can’t connect SFP+ to a device (SFP) that only supports 1 Gbps.

Related Article: Optical Module Maintenance Methods and Installation Tips

How Do Optical Transceiver Vendors Differentiate Their Transceiver Design?

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In order to get a bigger share of the market. Optical transceiver vendors are challenged in how to differentiate their optical transceiver design and give the products conform to common form factors. To understand the importance of transceiver differentiation, it is worth reviewing the purpose of multi-source agreement (MSA) transceiver form factors.

Common form factors arose so that optical equipment makers could avoid developing their own interfaces or being locked into a supplier’s proprietary design. Judged in those terms, MSAs have been a roaring success. Equipment makers can now buy optical intoptical transceiver designerfaces from several sources, all battling for the design win. MSAs have also triggered a near-decade of innovation, resulting in form factors from the 300-pin large form factor transponder MSA to the pluggable SFP+, less than a 60th its size.

But MSAs, with their dictated size and electrical interfaces, are earmarked for specific sectors. As such the protocols, line rates, and distances they support are largely predefined. Little scope, then, for differentiation. Yet vendors have developed ways to stand out. One approach is to be a founding member of an MSA. This gives the inner circle of vendors a time-to-market advantage in securing customers for emerging standards. The CFP MSA for 40- and 100-Gigabit Ethernet is one such example.

Some designs required specialist optical components that only a few vendors have, such as high-speed VCSELs used for the latest Fibre Channel interfaces. In turn, many vendors don’t have the resources—design teams and the deep pockets—needed to develop advanced technologies, such as those for 40- and 100-Gbps transponders, whether it is integrated optical devices or integrated circuits.

Being the first to integrate existing designs into smaller form factors is another way to differentiate oneself. An example is JDSU, which has integrated a tunable laser into the pluggable XFP MSA. Fiberstore also then launched tunable XFP which features with tunable and multi-protocol functions in order to further expand the product lineup of the 10G optical transceiver modules.

Optical transceiver vendors are also differentiating their products through marketing approaches. New-entrant Far Eastern vendors are selling optical transceivers directly to service providers and data center operators, bypassing equipment makers. They are also looking to differentiate on price, cutting costs where they can (including R&D) and focusing on bread-and-butter designs. They are quite happy to leave the leading vendors to make the heavy investments and battle each other in the emerging 40- and 100-Gbps markets.

Some people think differentiation doesn’t matter so much for optical transceivers since even if a vendor gets a lead, others inevitable will follow. And anyway, the cost of transporting traffic is still too high evenoptical transceiver market with the fierce competition instigated by MSAs. In turn, optical transceivers are now a permanent industry fixture and they can’t be conjured to disappear.

For optical transceiver vendors, however, the result is a market that is brutal. So can optical transceiver vendors differentiate their products? Of course they can. FS.COM (Fiberstore), a company devoting on the research & development, and offering fiber connectivity network solutions for carriers, ISPs, content providers and networks, is the global market innovator and application technology pioneer in the field of optical network devices and interconnection. In the future, they seem to change this market.

Unique Advantages of 10GBASE-T in Migrating Data Center to 10GbE

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Over the last decade, large enterprises have been migrating data center infrastructures from 100MB Ethernet to 1/10 Gigabit Ethernet (GbE) to support high-bandwidth, mission critical applications. However, many mid-market companies found themselves restricted from this migration to 10GbE technology due to cost, low port density and high power consumption. For many of these companies, the explosive growth of technologies, data and applications is severely taxing existing 1GbE infrastructures and affecting performance. So it’s high time for them to upgrade the data center to 10GbE. With many 10GbE interfaces options such as CX4, SFP+ Fiber, SFP+ Direct Attach Copper (DAC), and 10GBASE-T offered, which one is the best? In fact, the answer is 10GBASE-T.

Shortcomings of SFP+ in 10GbE Data Center Cabling
SFP+ has been adopted on Ethernet adapters and switches and supports both copper and fiber optic cables makes it a better solution than CX4, which is the mainstream 10GbE adoption today. However, SFP+ is not backward-compatible with the twisted-pair 1GbE broadly deployed throughout the data center. SFP+ connectors and their cabling were not compatible with the RJ-45 connectors used on 1GbE networks. Enterprise customers cannot just start adding SFP+ 10GbE to an existing RJ-45 1GbE infrastructure. New switches and new cables are required, which is a big chunk of change.

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Advantages of 10GBASE-T in 10GbE Data Center Cabling
10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in existing 1GbE switch infrastructures in the data centers that are cabled with CAT6, CAT6A or above cabling. As we know, 1GbE is still widely used in data center. 10GBASE-T is backwards compatible with 1GbE and thus will become the perfect choice for gradual transitioning from 1GbE deployment to 10GbE. Additional advantages include:

  • Reach
    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.
  • Power
    The challenge with 10GBASE-T is that even single-chip 10GBASE-T adapters consume a watt or two more than the SFP+ alternatives. More power consumption is not a good thing in the data center. However, the expected incremental costs in power over the life of a typical data center are far less than the amount of money saved from reduced cabling costs. Besides, with process improvements, chips improved from one generation to the next. The power and cost of the latest 10GBASE-T PHYs will be reduced greatly than before.
  • Reliability
    Another challenge with 10GBASE-T is whether it could deliver the reliability and low bit-error rate of SFP+. This skepticism can also be expressed as whether the high demands of FCoE could be met with 10GBASE-T. In fact, Cisco has announced that it had successfully qualified FCoE over 10GBASE-T and is supporting it on its newer switches that support 10GBASE-T in 2013.
  • Latency
    Depending on packet size, latency for 1000BASE-T ranges from sub-microsecond to over 12 microseconds. 10GBASE-T ranges from just over 2 microseconds to less than 4 microseconds, a much narrower latency range. For Ethernet packet sizes of 512B or larger, 10GBASE-T’s overall throughout offers an advantage over 1000BASE-T. Latency for 10GBASE-T is more than 3 times lower than 1000BASE-T at larger packet sizes. Only the most latent sensitive applications such as HPC or high frequency trading systems would notice any latency.
  • Cost
    When it comes to capital costs, copper cables offer great savings. Typically, passive copper cables are two to five times less expensive for comparable lengths of fiber. In a 1,000-node cluster, with hundreds of required cables, that can translate into the hundreds of thousands of dollars. Extending that into even larger data centers, the savings can reach into the millions. Besides, copper cables do not consume power and because their thermal design requires less cooling, there are extensive savings on operating expenditures within the data center. Hundreds of kilowatts can be saved by using copper cables versus fiber.

Conclusion
The 10GbE standards are mature, reliable and well understood. 10GBASE-T breaks through important cost and cable installation barriers in 10GbE deployment as well as offering investment protection via backwards compatibility with 1GbE networks. Deployment of 10GBASE-T will simplify the networking transition by providing an easier path to migrate to 10GbE infrastructure in support of higher bandwidth needed for virtualized servers. In the future, 10GBASE-T will be the best option for 10GbE data center cabling!

Knowledge of SFP Auto-Negotiation

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We usually see fiber optic transceiver with descriptions like “10/100/1000 copper SFP” shown in the picture below. Then what does “10/100/1000” mean? In fact, it refers to SFP modules that support 10/100/1000 auto-negotiation. With the function of auto-negotiation, SFP can operate on 10 Mbps, 100 Mbps, and 1000 Mbps. Some knowledge of SFP auto-negotiation will be given in this article.

Copper SFP Auto-Negotiation

What Is Auto-Negotiation?

Today a number of technologies, such as 10Base-T, 100Base-T, and 1000Base-T, use the same RJ-45 connector, creating the potential for connecting electrically incompatible components together and causing network disruption. To eliminate the possibility of dissimilar technologies interfering with each other, the Institute of Electrical and Electronics Engineers (IEEE) developed a protocol known as auto-negotiation. Auto-negotiation allows devices to perform automatic configuration to achieve the best possible mode of operation over a link. Devices with this feature will broadcast their speed (10 Mbps, 100 Mbps, and 1000 Mbps) and duplex (half/full) capabilities to other devices and negotiate the best between two devices.

Types of SFP Auto-Negotiation

There are two types of auto-negotiation that operate simultaneously within the SFP module. One is the 1000Base-T auto-negotiation, the other is 1000BASE-X auto-negotiation. The difference between them is that 1000BASE-T auto-negotiation is conducted over the Cat 5 cable between the two 1000BASE-T devices while 1000BASE-X auto-negotiation is typically conducted between two host systems over fiber. Usually, Gigabit SFP transceivers use auto-negotiation to advertise the following modes of operation: 1000Base-T in full or half duplex, 100Base-TX in full or half duplex, and 10Base-T in full or half duplex.

SFP Auto-Negotiation in Real Applications

A few cases of how SFP auto-negotiation operation works in an actual application are shown below:
Case1: A SFP is inserted into a switch with no copper cable.
Regardless of whether the MAC has 1000Base-X auto-negotiation turned on or off, 1000Base-X auto-negotiation will not complete. Because 1000Base-X auto-negotiation will never complete before 1000Base-T link is established.

Case2: After SFP is inserted into a switch w/ 1000Base-X auto-negotiation, copper cable is inserted.
SFP will store the 1000Base-X abilities advertisements from the MAC. 1000Base-T auto-negotiation will be restarted using abilities advertisements from the MAC. After 1000Base-T link is completed, SFP will send 1000Base-X abilities advertisements and acknowledgement codewords to the MAC. 1000Base-X link will then be established.

Case3: After SFP is inserted into a switch w/ no 1000Base-X auto-negotiation, copper cable is inserted.
SFP will detect that only idles are received from the MAC. 1000Base-T link will be established based on abilities set by hardware strap options on the PHY. After 1000Base-T link is established, the SFP will wait for 200 minutes and go into bypass mode. 1000Base-X link will then be established.

Case4: Both 1000Base-T and 1000Base-X link has been established. Copper cable is then unplugged.
When the copper cable is unplugged, 1000Base-T link will be broken. This will restart auto-negotiation both for 1000Base-X and 1000Base-T.

Case5: Copper cable is first plugged into the SFP, then SFP with cable is inserted into switch.
This case is the same case 2 and 3. If the SFP is powered up with copper cable already plugged in, it will go through the same auto-negotiation process.

After reading this article, you may know more about SFP auto-negotiation. Fiberstore have a lot of 10/100/1000BASE-T auto-negotiation 100m RJ45 copper SFP fiber optic transceivers in stock with high quality and low price. For more information, please visit fs.com.

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GBIC vs SFP—When to Choose What?

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GBIC and SFP are both a kind of hot-pluggable optical transceiver which is mainly used to convert between the optical signal and electrical signal. GBIC stands for Gigabit Interface Converter. SFP is short for Small Form-factor Pluggable. Usually, SFP is considered as an upgraded version of GBIC module. However, GBIC and SFP are equal in performance. The only major difference between them is their size. SFP module is much smaller than GBIC module. For this reason, the SFP is also called mini GBIC in most cases.

These years, due to the small size of SFP, GBIC module is being replaced by SFP. Why is this happening? In fact, the most common reason is that the big size of GBIC module was not feasible to provide more number of interfaces on a line card or a switch since it occupies more space. In order to resolve this issue people came up with SFPs which were smaller in size hence you can have more interfaces on the same line card or switch compared to GBICs. Let’s take an example, have you ever heard of a 48 port GBIC line card on 6500 switch. The answer is no, because it’s not feasible to have 48 big GBIC interfaces on the form factor of the line card. But a 48 port SFP line card exists.

gbic module

Knowing the differences between these two modules, then which one should you choose? In general, it actually depends on the line card or the switch you have. Usually, the line cards and switches comes with empty GBIC or SFP slots where you need to purchase the GBIC module or SFP modules respectively and insert in those empty slot. However, if you already have a switch or line card which has GBIC slots you have to use GBICs, simply because SFPs won’t fit in and vice versa.

Another case where you don’t have a switch or line card and want to make a decision whether to use a GBIC or SFP will actually depend on the number of interfaces required and availability of the switches and line cards specific model. For example, if you want two fiber interfaces on a line card on 6500 switch, you won’t go for a 48 port SFP line card, instead you’ll use a 2 port GBIC line card. If you need some 24 fiber interfaces you won’t use a 16 (or 18 not sure) port GBIC line card, you’ll use a 48 port SFP line card.

After reading this article, you may get a clear understanding of whether to use SFP module or GBIC module. Fiberstore provides all kinds of SFP modules, such as 1000BASE-T SFP, 1000BASE SX SFP, 1000BASE LX SFP etc. If you need to buy GBIC modules, I also recommend you to visit Fiberstore. All their GBIC modules come with a lifetime advance replacement warranty and are 100% functionally tested.

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