100G OTN Empowers IDC Backbone Network
100G OTN plays a big part in IDC backbone network construction. This article explains the current state of 100G OTN in IDC backbone networks, 100G OTN key technologies and how 100G OTN empowers IDC network construction.
100G OTN in IDC Development
Nowadays cloud services, Internet of things, artificial intelligence are all the rage. A flood of various applications, coupled with the scale deployment of live streaming and high definition videos, has contributed to the rapid growth of bandwidth demand of IDC backbone networks. Related surveys have shown that the average annual traffic growth rate of internet providers and network operators has overtaken their revenue growth rate. To alleviate their financial pressure, internet providers and mobile network operators are all looking for ways to bring down the transmission cost per unit traffic.
One of the most effective ways to reduce TCO is to improve the transmission capacity. The completion of 100G standard and the introduction of OTN help make a breakthrough. Nowadays, most equipment manufacturers have in stock a line of 100G products to grapple with the rapidly growing demands for higher data rate and bandwidth in IDC backbone networks.
100G OTN Key Technologies
We will discuss key technologies used in 100G OTN in the following part.
100G OTN Line Modulation
Modulation signal rate has a great influence on 100G OTN network performance since it's closely related to a number of physical limitations that hinder the long-distance transmission of OTN. The higher modulation rate you use, the more susceptible you are to noise or interference. Quadrature Phase Shift Keying (QPSK), a modulation technique, is often used with polarization multiplexing (PM) to reduce the modulation rate of 100G systems.
To be specific, the 100G signal (The bit rate of 100G signal is 112Git/s or higher) is divided into four low-speed signals at the transmitting end. Each signal is 28Gbit/s with OTN and FEC overhead. The light emitted by the laser is decomposed into vertical and horizontal polarization states. PM uses these two polarization states that have the same frequency to carry signals. The optical signal of two polarization states is modulated by QPSK before they're coupled and output together. This can greatly reduce the modulation rate and baud rate, and further reduce the power consumption and cost of IDC backbone networks.
Coherent Reception and DSP
Because polarization state of PM-QPSK optical signals change randomly in long-distance transmission, the frequency and phase of the the local optical oscillator at the receiving end is different from those of the received optical signal. High-speed digital signal processing (DSP) is used to solve this problem since it can process the received signal.
Using advanced DSP compensation technology, the polarization-mode dispersion (PMD) tolerance of 100G system can be greatly improved, reducing the transmission cost incurred by PMD in IDC backbone networks. In addition, there will be higher optical receiving sensitivity.
Out-of-Band FEC Scheme
OTN defines an out-of-band FEC scheme that is applied to optical signal before transmission. FEC significantly improves tolerance to network impairments happening in high-speed transmissions. It also detects and corrects errors in the optical link, greatly increasing system margin for a given Bit Error Rate (BER). FEC makes it possible to extend the distance between optical repeaters in IDC backbone networks. This helps not only reduce overall capital and operational expenses but also simplify IDC network architecture where fewer amplifier sites are needed.
How 100G OTN Empowers IDC Network Construction
Behind 100G OTN's popularity lie a series of crucial benefits it offers. The following illustrates how 100G OTN empowers IDC network construction.
Efficient Utilization of 100G Pipeline
The complete operation, administration and management capability of 100G OTN contributes to the efficient utilization of 100G pipeline. Compared to WDM networks without channel level monitoring and management capability, 100G OTN can realize the active perception of the wavelength channels, and provide level 6 connection monitoring capability, greatly improving network manageability and service security. In addition, OTN can realize hierarchical and segmented channel level management for application scenarios typical in IDC networks where multiple operators and subnets are involved.
Great Protection Mechanism
100G OTN has a variety of network-level protection mechanisms, greatly improving network reliability and security in IDC networks. Those protection mechanisms cover both optical layer and electrical layer protection, including optical line and channel protection, SNCP protection, ODUK 1+1 protection, ODUk ring network protection. Optical channel 1+1 protection is commonly used for optical layer protection, while ODUK 1+1 protection is mainly for electric layer protection. All help avoid service interruption caused by component failures and ensure high-level network security.
Differentiated Service Offerings
100G OTN enables network operators to establish, protect, and restore services according to specific SLAs and policies with enhanced programmability. With packet enhanced OTN products, an IDC network can realize unified transmission of TDM and packet services, and have processing capabilities such as ODUk crossover, packet switching, and VC crossover. Therefore, 100G OTN is a great choice to match various service ports and solve multi-service carrying.
Summary
As the 100G OTN industrial chain has already matured, the scale deployment of 100G OTN in IDC networks will become more and more common. In addition, with the maturity of 100G key technologies, IDC networks will deliver smooth and efficient network performance with easy management and high-level security.
