Understanding SFP Optical Modules
SFP is the abbreviation of SMALL FORM PLUGGABLE, which can be simply understood as an upgraded version of GBIC. The volume of the SFP module is reduced by half compared to the GBIC module, and more than double the number of ports can be configured on the same panel. The other functions of the SFP module are basically the same as those of the GBIC.
Some switch manufacturers call the SFP module a miniaturized GBIC (MINI-GBIC). The volume of the SFP module is reduced by half compared to the GBIC module, and the number of ports can be more than doubled on the same panel. The other functions of the SFP module are basically the same as those of the GBIC. (Mini-GBIC). Abbreviation for Gigabit Interface Converter, which is an interface device that converts gigabit electrical signals into optical signals. The GBIC is designed to be hot-swappable. GBIC is an interchangeable product that complies with international standards. Gigabit switches designed with GBIC interface occupy a large market share in the market due to their flexible interchangeability.
GBIC modules are divided into two categories:
One is the GBIC module used in ordinary cascading to realize ordinary connection with other switches;
The second is to stack dedicated GBIC modules to achieve redundant connections with other switches.
SFP modules further compress size and power consumption by placing CDR and electrical dispersion compensation outside the module.
1. SFP Standardization
SFP transceivers are specified by a Multilateral Agreement (MSA) between competing manufacturers. The SFP is designed according to the GBIC interface, allowing a greater port density (the number of transceivers per inch on the side of the motherboard) than the GBIC, so the SFP is also called "mini-GBIC". The related small package transceiver (SFF transceiver) is smaller in size than SFP, but SFF is soldered to the motherboard as a pin through-hole device, rather than inserted into the edge card slot superior.
2. SFP type
SFP transceivers come in a number of different transmit and receive types, and the user can select the appropriate transceiver for each link to provide the "optical performance" that can be achieved based on the fiber type available, such as multimode or singlemode. The available optical SFP modules are generally divided into the following categories: MMF (SX) at 850 nm wavelength/550 m distance, SMF (LX) at 1310 nm wavelength/10 km distance, XD at 1550 nm wavelength/40 km distance, 80 km distance ZX, EX or EZX for 120 km distance, and DWDM.
SFP transceivers also provide a copper interface, enabling host devices designed primarily for fiber-optic communications to communicate over UTP network cables. There are also wavelength division multiplexing (CWDM) and single-fiber "bidirectional" (1310/1490 nm wavelength upstream/downstream) SFPs.
3. Optical fiber classification
Optical fibers are divided into multi-mode optical fibers and single-mode optical fibers. Among them, multi-mode optical fibers are widely used in short-distance communications due to their relatively cheap light-emitting devices and easy construction. Multi-mode optical fibers are further divided into 50um core diameter and 62.5um core diameter. There are two core diameters, of which 62.5um is more common, but the performance is not as good as 50um.
Single-mode fiber is generally used for long-distance communication, with a core diameter of 9um, and the transmission distance on single-mode fiber reaches 10 kilometers, 20 kilometers, 70 kilometers, and 120 kilometers respectively. Generally, switch manufacturers only provide 10km and 70km models on single mode, and 20km products can effectively save the overall cost of system integrators' specific network solutions. 120km products are used in special ultra-long running environments.
4. The difference between SFP
SFP optical modules usually use dual LC interfaces, and there are also single-core SFP optical modules. In terms of speed and fiber type, it can be divided into four types: 100M single multimode and 1000M single multimode.
2. The difference between SFP multi-mode and single-mode
At present, I have encountered several SFP problems in the project, and there are actual or possible problems related to the type of optical module, so I specially found some multi-mode and single-mode information.
The following are some concepts and differences between multimode and singlemode SFPs that have been learned.
According to the wavelength, there are 850nm/1310nm/1550nm/1490nm/1530nm/1610nm, the wavelength of 850nm is SFP multi-mode, and the transmission distance is below 2KM;
The wavelength of 1310/1550nm is SFP single-mode, and the transmission distance is more than 2KM. Relatively speaking, the price of these three wavelengths is cheaper than the other three.
If the bare module is not marked, it is easy to be confused. Generally, manufacturers will distinguish the color of the pull ring. For example, the black pull ring is multi-mode, and the wavelength is 850nm. The blue, yellow and purple pull rings are single-mode, and the wavelengths are respectively It is 1310nm, 1550nm, 1490nm.
Multimode:
Almost all multimode fibers are 50/125µm or 62.5/125µm in size, and the bandwidth (the amount of information transmitted by the fiber) is typically 200MHz to 2GHz. Multimode optical transceivers can transmit up to 2 kilometers through multimode optical fibers. Light-emitting diodes or lasers are used as light sources. The pull tab or body color is black.
Single mode:
Single-mode fiber is 9/125 μm in size and has unlimited bandwidth and lower loss than multimode fiber. The single-mode optical transceiver is mostly used for long-distance transmission, sometimes reaching 100 kilometers. LDs or LEDs with narrow spectral lines are used as light sources. The pull tab or external color is blue, yellow or purple.
Differences and connections:
Single-mode fiber is cheap, but single-mode equipment is much more expensive than comparable multi-mode equipment. Single-mode equipment typically operates on both single-mode fiber and multi-mode fiber, while multi-mode equipment is limited to operation on multi-mode fiber.
With the approach of single-mode and multi-mode SFP optical modules this year, the adoption of single-mode optical cables and single-mode modules has become the mainstream. Single-mode is clearly superior to multi-mode types in use.
3. The difference between SFP and BiDi SFP
As we all know, a common SFP module usually has two ports, one is the TX port for transmitting signals, and the other is the RX port for receiving signals. Unlike common SFP modules, BiDi SFP modules have only one port and use an integral WDM coupler on a single fiber to transmit and receive signals.
SFP and BIDI SFP connection methods
All SFP modules must be used in pairs. For common SFPs, we should connect two SFPs with the same wavelength together. For example, we use 850nm SFP at one end, then at the other end we have to use 850nm SFP.
For BiDi SFP, since it transmits and receives signals with different wavelengths, we should connect two BiDi SFPs with opposite wavelengths together. For example, we use TX1310/RX1550nm BiDi SFP at one end, then at the other end we should use TX1550/RX1310nm BiDi SFP.
BiDi SFP Application
At present, BiDi SFP is mainly used for fiber-to-the-home deployment P2P (point-to-point) connection. An FTTH/FTTB Active Ethernet network consists of a central office (CO) connected to customer premises equipment (CPE). BiDi SFPs allow bidirectional communication on a single fiber using wavelength division multiplexing, which makes CO and CPE connections simpler.
4. The difference between SFP, SFP+ and XFP
Many people don't know the difference between SFP+ and SFP and XFP, so sometimes it brings unnecessary trouble. The 10G module has undergone development from 300Pin, XENPAK, X2, and XFP, and finally realized the transmission of 10G signals with the same size as SFP, which is SFP+. With its advantages of miniaturization and low cost, SFP+ meets the high-density optical module requirements of equipment, and has gradually replaced XFP to become the mainstream of the 10G market.
SFP package---hot-swappable small package module, currently the highest rate can reach 4G, mostly using LC interface.
SFP+ package---standard package, the working rate is 10G, which can meet the application of Ethernet 10G.
XFP package---a standardized package for serial 10G optical transceiver modules.
Advantages of SFP+ optical modules:
1. SFP+ has a more compact form factor than X2 and XFP packages (same size as SFP);
2. It can be directly connected with the same type of XFP, X2, XENPAK;
3. The cost is lower than that of XFP, X2 and XENPAK products.
The difference between SFP and SFP+:
1. The dimensions of SFP and SFP+ are the same;
2. The maximum rate of SFP can reach 4G, and the rate of SFP+ is 10G;
3. SFP protocol specification: IEEE802.3, SFF-8472;
4. SFP+ supports digital diagnosis.
Differences between SFP+ and XFP:
1. Both SFP+ and XFP are 10G fiber optic modules, and can communicate with other types of 10G modules;
2. SFP+ is smaller in size than XFP;
3. Because of its smaller size, SFP+ moves signal modulation functions, serial/deserializer, MAC, clock and data recovery (CDR), and electronic dispersion compensation (EDC) functions from the module to the motherboard card;
4. The protocol that XFP complies with: XFP MSA protocol;
5. Protocols compliant with SFP+: IEEE 802.3ae, SFF-8431, SFF-8432;
6. SFP+ is a more mainstream design;
7. SFP+ protocol specification: IEEE 802.3ae, SFF-8431, SFF-8432.
5. Advantages of BiDi SFP+ Optical Module Cable Failure
With the rapid development of communication, the demand for wireless bandwidth in the market is getting higher and higher, so many optical communication product manufacturers continue to develop new products to meet the market demand. BiDi SFP+ optical modules are also produced in this situation. Next, I will share with you the use of BiDi SFP+ optical modules.
BIDI is a single fiber bidirectional optical module. That is, BiDi (Bidirectional). The BIDI optical module has only one port, which is filtered by the filter in the optical module, and simultaneously transmits the 1310nm optical signal and receives the 1550nm optical signal, or vice versa.
Therefore, this kind of module must be used in pairs, and its biggest advantage is to save fiber resources. Commonly used wavelengths of BIDI optical modules are TX1310/RX1550nm; TX1310/RX1490nm; TX1550/RX1490nm.
SFP+ optical module, (10 Gigabit Small Form Factor Pluggable) is a hot-pluggable, communication protocol-independent optical transceiver, usually the wavelength of transmission light is 850nm, 1310nm or 1550nm, for 10G bps SONET/SDH , Fibre Channel, gigabit Ethernet, 10 gigabit Ethernet and other applications, also including DWDM links.
Therefore, BiDi SFP+ optical modules are developed and designed based on CPRI (Common Public Radio Interface) and OBSAI (Open Base Station Architecture Initiative) standards. BiDi SFP+ optical module adopts SFP+ small package, meets protocol standards such as SFF-8431 MSA, SFF-8432 and SFF-8472, and supports single-fiber bidirectional transmission. Not only that, but also supports different transmission distances, including 10km, 20km and 40 km. In addition, the operating temperature range is very wide, and it can be easily operated from 0°C to 75°C, making it the first choice for indoor and outdoor communication networks, providing them with high-speed and stable signal transmission channels. (Graphic and text to understand the knowledge of fiber optic modules)
To sum up, the advantages and characteristics of BiDi SFP+ optical modules:
The transmission distance of wavelength TX1270/RX1330nm is 10KM/20KM/40KM/60KM; the transmission distance of wavelength TX1490/RX1550nm is 80KM
Single power supply +3.3V power supply
LVPECL/PECL data interface
Working temperature 0℃-70℃※ Comply with GR-468-CORE requirements
Complies with Laser Class 1 and meets IEC60825-1 requirements
RoHS compliant products available
BiDi SFP+ optical modules are widely used in existing wireless communication base stations and new wireless communication base stations, and build a high-speed and stable signal transmission bridge between communication base stations and optical fiber antennas. Shenzhen Jufeng Optoelectronics Co., Ltd. is a company dedicated to the R&D, design, production, sales and service of optical communication network products. In order to meet the needs of the majority of the market and continue to develop and innovate, the BiDi SFP+ optical module developed by Jufeng Optoelectronics has won many Customer reviews and feedback. Further Reading: 5 Best Network Troubleshooting Software
6. Aging test of SFP module
Quality is important to all products.
In order to control the quality of products, we will conduct some tests, including incoming inspection, product parameter test, distance test, switch test and aging test.
