With the rapid development of science and technology, optical communication is increasingly widely used in our actual life. And the need for network technology is higher and higher, so that the 100G optical transceivers have been gradually sold on the market. Maybe most of you have already had an overview on what are 100G optical modules, but this post will go deeper into the background, current problems as well as main types of 100G optical transceivers.
1. The Development Background of 100G Optical Transceivers
The earliest developed 100G optical module was developed in 2010, which form factor is CFP. At that time, IEEE launched three standards (SR10, LR4 and ER4) for 100G optical modules, separately focusing on the 100m, 10Km and 40Km transmission. Then the IEEE standard added new 100G SR4 project, but in 2013 it did not reach consensus. By 2016, the 100G optical transceiver modules for various data centers mostly used the 25Gbps Serdes program. And the 100G optical modules that use the 50Gbps Serdes plan slowly appeared.
2. Main Challenges of 100G Optical Modules
1. Channel Distance: The DWDM system supporting the 50GHz wavelength distance is very extensive. The 100G optical module needs to be satisfied with the condition of supporting the 50GHz wavelength distance, therefore, the pattern of high spectral power should be used.
2. OSNR (optical signal-to-noise ratio): Under the same pattern, 100G optical module requires 10dB higher than 10G optical module and 4dB higher than 40G optical modules. Therefore, a low OSNR tolerance code and high coding gain FEC algorithm.
3. CD margin: Under the same conditions, the dispersion tolerance for 100G optical modules is 1/100 of 10G optical modules, accounting for 40G optical module 16/100. It can use dispersion compensation technology, in the electric field or the optical domain compensation to complete the dispersion compensation for each wavelength.
4. PMD tolerance: Under the same conditions, PMD (polarization mode dispersion) tolerance of 100G optical modules is 1/10 of 10G optical module, accounting for 4/10 of 40G optical module, so you need to choose coherent reception and digital signal processing.
5. Non-linear effects: 100G optical module than 10G / 40G optical module nonlinear effects more messy.
3. Main Types of 100G Optical Transceivers
According to the different form factors, 100G optical modules mainly include the several types: CFP / CFP2 / CFP4, CXP and QSFP28. Among all of them, CFP / CFP2 / CFP4 and CXP are form factors of early 100G optical modules and QSFP28 are new generation of form factor for 100G optical modules.
With the advantages of high port density, low power consumption & cost and so on, it has gradually become the mainstream 100G optical module form factor. There are four main types of 100G QSFP28 optical transceivers, including 100G QSFP28 SR4, 100G QSFP28 LR4, 100G QSFP28 PSM4, and 100G QSFP28 CWDM4. The principle of the 100G QSFP28 optical module is similar to that of the 40G QSFP + optical module. The 100G optical signal is transmitted in 4 × 25 Gbps mode.
All of the 100G optical transceivers can be founded in Gigalight. It focuses on the development of optical communication products, not only many types of 100G optical modules, but also in accordance with the requirements of users to customize the 100G optical modules with satisfactory conditions.
The development of 100G Ethernet standards and technologies is driven by demand but ahead of schedule. According to the plan of the IEEE802.3ba Task Force (TF), it is expected that standards will be finalized by mid-2010, but the real business time depends on more factors.
First of all, under the premise of standard maturity, it also needs real network demand driven and is in the interest of operators. The main factors of bandwidth demand include:
1. The increasing business is based on IP, as it is now described by ALL IP;
2. Almost all the IP packets are sent from the source to sink, the whole process is encapsulated in the Ethernet frame;
3. The technology used in Ethernet over TDM /Ethernet has matured and traditional voice compatibility is no longer a problem;
4. Ethernet encapsulation is simpler and cheaper than SONET / SDH encapsulation.
These decisions to upgrade the Ethernet interface to 100 Gbit / s are both objective and urgent. Network communications can be achieved on 100G Ethernet networks with "accelerated network communications and improved application performance", enabling fast access to data stored in data Center of the various applications, implementation of bandwidth management, cache, compression, path optimization and protocol acceleration and other functions. For details, see the application scenario in Figure 2 [9]. For the application at the convergence layer, the downlink port is switching to 10 Gbit / s and the uplink can only use 10 Gbit / s port link aggregation. If there is a 100G Ethernet interface, you can improve the management, distribution and efficiency of data flow. For the data center, with the increase of 10 Gbit / s interface, there is also the demand for upstream and inter-connected high-speed interfaces. For the efficient transmission of backbone networks, we also expect the 100G high- Interface and transmission maturity.
The P802.3ba standard has fully considered the maturity of related standards and technologies of the electrical interface when adopting the 10.312 5 Gbit / s inter-chip interconnection transmission channel. The multimode parallel optical interface can support the OM3 optical fiber to meet the requirements of 100 m Even over longer distances; single-mode 40GBASE-LR4 is economical with coarse wavelength division multiplexing (CWDM); 100GBASE-LR4 uses DWDM with 25.781 25 Gbit / s per wavelength and 1 295-1 310 nm wavelength, Fully use the original fiber, integrated technology and cost, the standard selection of technologies are practical and feasible, to help promote the 100G interface in the local and metropolitan area within the commercial.
For the whole network of use, serial 100GE transmission standard and technology before maturity can use the reverse multiplexing technology. 100GE services of 10 × 10GE or 4 × 25GE interfaces are adapted to OTU2 / OTU3 through ODU2 / ODU3 and transmitted through multiple wavelengths in 10G / 40G optical networks. It is possible to eliminate the need to redesign and modify existing 10G / 40G DWDM optical networks. The transmission pattern is still ODB / DRZ / EPR - Differential Quadrature Phase Shift Keying Control (eRZ-DQPSK). This model can be used 10G / 40G existing mature optoelectronic devices, and the entire system performance and 10G / 40G system consistent. This scheme can realize the smooth network upgrade, meet the operator's cost expectation, and the device is ripe [10].
Therefore, the current cost and demand point of view, 100 Gigabit Ethernet commercial first in the metropolitan area network is more feasible solution, because in the MAN, a lot of data on the road at any time, without a variety of compensation Device transmission system will greatly simplify the network design, 100 Gigabit Ethernet just to meet this demand, while high bandwidth to meet the metropolitan area network 40% annual traffic growth. In a word, the development demand of 100 Gigabit Ethernet has already been obvious, and the cost advantage will also be strengthened constantly. However, the transmission of 100 Gigabit Ethernet transmissions needs constant technical improvement from modulation mode to operation management and maintenance.
In addition to this technology upgrade, in addition to 100 Gigabit Ethernet, other protocols, including Fiber Channel, Infiniband and SONET, will also appear in 40/100 Gbit / s networks. In the late 1990s, Ethernet ports Equipment prices have dropped more than twice as fast as competitive ATM and Fiber Distributed Data Interface (FDDI). However, 40 Gbit / s and faster networks share many of the same FPGAs, SERDES, and encoding technologies, making it difficult for any device to achieve cost advantage by mass production. 100G Ethernet may not be as dominant as it used to be.
In general, 100 Gigabit Ethernet technology is a very viable with high-profile technology that everyone is enthusiastic to participate in, but the standards and technologies themselves have yet to mature, and commercial pilots will be launched by the end of 2009 but mature commercial is expected to be beyond 2012.
In addition to the technical and commercial challenges, the opportunities presented are enormous, starting with the opportunity for research institutes to discover and innovate; bringing new, high-return markets to component and module suppliers (but also requires high investment); For system suppliers is a comeback and take this opportunity to lead the market.
As we all know, QSFP28 optical transceiver is considered as the mainstream modules for 100G Ethernet. But how to select QSFP28 optical transceivers for 100G Ethernet? Gigalight is able to provide various kinds of QSFP28 products, including QSFP28 DAC, QSFP28 AOC, and QSFP28 optical transceivers with different interfaces such as 100G SR4 / LR4 / PSM4 / CWDM4 optical transceivers. For more details, please visit its official website.