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BP1037 Transitioning to DCB with EqualLogic PS series Storage Solutions 7
Power and cooling
The benefits realized from reducing the number of cables and network cards virtualization extends to
the power and cooling needs of the datacenter. As the traffic flows converge onto one network
instead of several, the resulting number of network switches goes down. Along with the switch count,
the power and cooling requirements for the datacenter also decrease. By using fewer cables, the
airflow characteristics and cooling efficiency in data center racks improves. One or two 10Gb fibre
connections per server take up significantly less volume than four or more 1Gb copper cables per
server. With more cables multiplied across the servers in a rack, cooling airflow paths can be inhibited.
Cost
As the cost of 10Gb Converged Network Adapters (CNAs) continues to fall, the economic benefits of
converging multiple traffic flows onto 10Gb Ethernet will increase. As the size and complexity of your
data center increases, it will become far more cost-effective to purchase and deploy fewer ports of
10Gb DCB Ethernet than many more ports of 1Gb non-DCB Ethernet.
2.3 DCB terminology
Data Center Bridging (DCB) is a set of IEEE 802.1Q extensions to standard Ethernet, that provide an
operational framework for unifying Local Area Networks (LAN), Storage Area Networks (SAN) and
Inter-Process Communication (IPC) traffic between switches and endpoints onto a single transport
layer.
For an end-to-end DCB network to be properly configured there are various 802.1Q components
utilized. The standards include:
• Priority-based Flow Control: (PFC; IEEE 802.1Qbb) Expands the function of the standard class
of service structure of Ethernet to apply pause functionality on traffic, based on the class of
service settings. This ensures that one type of traffic does not affect other types of traffic that
have differing classes of service.
• Enhanced Transmission Selection: (ETS; IEEE 802.1Qaz) Provides administrators with the
ability to separate or group multiple classes of service together and then define a guaranteed
minimum bandwidth allocation from the shared network connection.
• Datacenter Bridging Capability Exchange: (DCBx; IEEE 802.1Qaz) Allows for communication
of DCB capabilities between network components. This protocol enables network
components to sense the DCB capabilities of neighboring devices and ensure consistent
configuration.
• Congestion Notification: (CN; IEEE 802.1Qau) Enables DCB switches to identify primary
bottlenecks and take preventative action to ensure that these points of congestion do not
spread to other parts of the network infrastructure.