What is DCI Box

Origin of DCI network

 At the beginning, the data center was relatively simple, with a few cabinets + a few high-P air conditioners in a random room, and then a single common city power + a few UPS, and it became a data center. However, this kind of data center is small in scale and low in reliability. The Internet, which has been developing crazily since the end of the 1990s, has also increased the demand for data centers. Therefore, there is an unsolvable problem in this type of data center: insufficient space , Insufficient power supply, no redundancy, and no SLA guarantee, making users start to find another data center for business deployment. At this time, the new data center and the old data center began to have network interconnection requirements, resulting in the initial DCI network, that is, Data Center Inter-connect, which includes technologies at the physical network level and the logical network level.

 The initial DCI network was directly interconnected through the Internet. Later, in consideration of security, encryption was used, quality of service was considered, dedicated lines were used, and bandwidth was directly connected by optical fiber.

Development of DCI network

The development of DCI networks from Internet interconnection, to several M dedicated lines, to the current multi-10T WDM interconnection is not a long time, objectively, it is a response to the development of the Internet. Initially, users use the public network VPN tunnel to transmit their services directly through the public network. This method is affected by various environments of the public network (global network bandwidth congestion, inferior routing, line jitter, link reset, firewall, etc.) Influenced by cost and cost, it is suitable for small traffic, low bandwidth quality requirements, non-real-time, and low security requirements. Later, the business in the data center attracted more and more attention, and the business began to gradually increase deployment, and the number of servers increased linearly. . After a large number of services are deployed, these services transmitted through the network have an increasing impact on companies and industries, so the requirements for the network are also getting higher and higher, first reflected in bandwidth and link stability, so data center users begin to Leased operator circuit dedicated lines, MSTP dedicated lines carried on the SDH network have begun to sell well due to their high stability, larger bandwidth, and high degree of operator multiplexing.

Later, with the continuous explosive development of business, the data between data centers began to have requirements for delay and redundancy, especially for financial customers, who had particularly high requirements for delay, so the requirements for dedicated lines were also

increased; Or, users begin to require large granularity, such as 2.5G, 10G single-link bandwidth, and also require dual-routing protection to ensure that the LSA reaches 4 to 5 9s.

 Even so, the power of the development of the Internet is amazing, and business trends such as log transmission and database synchronization are growing. In consideration of cost, delivery time, service quality, etc., top companies (especially Internet companies with big data like Google and FB) have begun to build DCI networks by renting bare optical fibers without operators. At the beginning of using bare optical fiber, it was also the way to run a single signal through a single optical fiber. For example, a pair of optical fibers can use a 10G ZR module to transmit 80 kilometers away. enough. However, the disadvantage of this method is that on the one hand, the amount of optical fiber usage increases linearly with the bandwidth, and the cost increases; A long-standing and difficult problem), and at this time, the 10G bandwidth of a single fiber cannot meet the needs of business growth, so the DCI network began the WDM era.

In the WDM era, two methods appeared in the DCI network, that is, coarse wavelength division CWDM and dense wavelength division DWDM. Based on cost considerations, some initial users used 10G CWDM optical modules for DCI interconnection using CWDM technology. However, this system supports up to 16 waves of 10G, and EDFA cannot amplify the signal at the wavelength of CWDM. , and its passive relay distance is also quite limited. Therefore, as the demand for large-scale data transmission continues to rise, users have to start using DWDM systems with higher capacity and performance.