22 March 2017
OXC promote DC upgrading in Cloud era
1. Cloud data center (DC) push network industrial upgrading.
The deployment of data centers are dependent on a number of factors, for example, availability of space, electrical power supply, proximity to users, network’s robustness, disaster recovery, etc. As a result, distributed and dispersed data centers are more and more popular. The distributed data centers comprise a resource pool of computing, storage and so on, and altogether they form a cloud architecture of data center. A cloud data center has the following characteristics:
(1)Interconnection among data centers has high traffic volume. DC based backbone network, which consists of several super nodes and tens of province nodes, has a requirment of hundred level Tb/s switching bandwidth.
(2)Tens of thousands of full-mesh interconnections will estabilish among data centers. It need one-hop optical path to make sure fast services deployment and migration. On the other hand, the high reliability and low latency also should be ensured for customer’s better experience.
(3) The resources of data center are dynamically allocated to different end users due to the resource pool nature of the cloud interconnections. Moreover, the bandwidth varies from time to time by regular data migration and maintenance, requires fast and flexible bandwidth self-regulation to deal with the burst switching among data centers.
2. Traditional MD-ROADM cannot meet the requirements from newly emerging DC interconnections
Large-scale optical wavelength switching is needed because of the large traffic volume (tens to hundreds of Tb/s), full mesh connections, and dynamic
traffic (reconfigurable bandwidth requirement), Although modern multiple-degree reconfigurable optical add/drop multiplexer (MD-ROADM
) has wavelength switching capability, it has inevitable limitations. Plenty of building blocks lead to the massive size, and their associated complex fiber connections result in difficult operation and maintenance. MD-ROADM use multicast switch (MCS) for wavelength add/drop, making the swithcing limited no more than 8 demension.
3. OXC network provide high-efficient solutions for DCI
Obviously, limited by integration, fiber connection, switching demension
and power consumption, MD-ROADM can not satisfy the future Cloud DC swithing. As a epochal all optical switching technologies, OXC has its own advanced characteristics as follow:
(1)Big bandwidth for 300/600 Tb all optical switching;
(2) Support more than 32 demension multi-direction switching;
(3) Compact size and high integration, only one slot for one direction;
(4)All optical backplane implement fiber free, making easier operation and management;
(5) High flexibility with reconfigurable wavelength switching;
(6) Low insertion loss, low power comsumption by less OAs;
In Lineside, a large scale 1´N (N>30) WSS is used to support the full mesh connections. State-of-the-art free space optics design enables the large scale WSS while reduces the size to only a half of low-demension WSS in conventional ROADM. Basing on high-density integration technology, OXC can assembly OAs, optical detection module and conpact WSS matrix on one line card, implementing that one slot for one direction.
Second, in tributary side, OXC use add drop wavelength selective switches (ADWSS) instead of MCS and OAs for of local wavelength adding and droping. An ADWSS is actually an M´N WSS. By using the up-to-date technology of liquid crystal on slicon(LCoS), it can freely select any one or multiple wavelenghth from input ports, and than flexibly recombine and send them to any outpt port. Moreover, the insertion loss for optical switching is very small, thus OAs are not needed.
Third, an optical backplane is used to interconnect the ports of the 1´N WSS’s and the ADWSS’s, replacing the numerous fiber connections of tranditional MD-ROADM. Flexible wavelength dispatch and dynamic bandwidth configuration can be easily operated by solftware setup .Wavelength monitoring techniques and functions are included, which can conveniently monitor the optical path and performance of the signals (every wavelength) passing through the OXC.
In summary, next generation optical layer based on OXC will be the key to interconnections within and between cloud networks. By converging the physical pipe and optical parameters, and promoting hardware resource pooling, the network resource can be visualized and controlled by SDN in order to gain maximum agility for the all-optical DC-centric network in future.
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