Datacenter holds thousands and even tens of thousands of physical servers as an integral part of enterprise designed to support business applications and provide some services such as,

 •  Data storage, management, backup and recovery
 •  Productivity applications such as email
 •  Powering gaming communities
 •  High-volume e-commerce transaction.

The data centers can be isolated into the following three subcategories,

 •  Public multitenant
 •  Private multitenant
 •  Private single-tenant

The unique features of DCNs present in SDN are :

 •  Large scale
 •  High power density
 •  High reliability
 •  Vast application diversity

Data Center Network (DCN) is scheduled with optical, electrical and wireless transmission technologies. Lots of proposals focused on operating the DCN to achieve various objectives, such as,

 •  Bandwidth guarantee
 •  Low service latency
 •  Low power consumption
 •  High network robustness
 •  High network utilization

DCN has raised great concerns and several solutions correspondingly to the following challenging venues that pursued particularly as,

 •  Multicast
 •  Cross-system optimization
 •  Modular data center
 •  Merchant silicon switch

Multicast: Sending concurrent data from source to destination that widely exists in data centers.

Cross-system optimization: An integral part of data server networks is a communication backbone, as existing solutions are often limited to a single domain.

Modular data center: It helps ease the complexity of putting thousands of servers in a shipping container to a modular data center as a turn-key solution for data center deployment gaining research attention.

Merchant silicon switch: It is explored as a building block of DCN to step further from an existing approach to construct with commodity switches. It allows regular upgrading to closely follow up with the latest generation switch silicon rather than waiting for upgrades.

Software Defined Networking in Data Centers is envisioned as one of the most promising solutions, and a good deal of existing research for DCNs that implement SDN-based network devices like a switch with OpenFlow or Application Centric Infrastructure (ACI).

Challenges of SDN-based DCN are referred to as :

 •  Data security
 •  Mobile enterprise
 •  Capacity planning
 •  Real-time reporting
 •  Balancing cost controls efficiency