Data Center Bridging is a collection of standards being worked on by the IEEE in an effort to provide a more robust form of Ethernet for data center communications.  In doing so, the standards bodies and manufacturers hope to provide a single communications mechanism for all devices within the data center.  To understand the changes needed to enhance Ethernet, it is important to understand where it began.

Ethernet is the dominant transport technology in networking and by design allows for data loss.  When Ethernet was originally created it was based upon a bus technology using coax cable with taps to provide connectivity to individual devices.  Ethernet was designed with CSMA/CD which is Carrier Sense Multiple Access with Collision Detection.  This mechanism allowed Ethernet to recover from collisions due to two or more nodes attempting to communicate at the same time.  This mechanism allows for data to be lost and retransmitted on an Ethernet network.

Data Center Bridging is an effort by the standards bodies including the IEEE to enhance traditional Ethernet for use within the data center to provide a unified technology for all data center communications including network, storage and management.   The minimum enhancements to Ethernet to support Data Center Bridging are Priority Based Flow Control, Enhanced Transmission Selection, and Data Center Bridging Exchange Protocol.

Priority Based Flow Control creates eight separate virtual links on each physical link.  Each virtual link can be paused independently from the others.  This allows the creation of a loss free virtual link across the physical link.  In addition, quality of service can be configured for each virtual link.

Enhanced Transmission Selection allows differentiation between traffic of the same priority class.  This leads to the concept of priority groups.  Traditional QoS mechanisms allow for different traffic classes. ETS creates priority groups within the classes for further control over network traffic.

Data Center Bridging Exchange Protocol is used by devices to discover one another and exchange information about each device’s capabilities.  By creating a protocol for capabilities exchange, devices can better understand the capabilities and limitations of their peers with a Data Center Bridged environment.

Data Center Bridging allows customers the ability to create a converged network within the data center that incorporates networking, management and storage onto a single transmission medium.  It simplifies the cabling within the data center and allows organizations to adapt rapidly to changing business needs.  For more information on Data Center Ethernet see the links below.

http://www.ieee802.org/1/pages/dcbridges.html

http://www.cisco.com/en/US/partner/netsol/ns783/index.html

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