Administrator Guide
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Data Center Bridging (DCB)
On an I/O Aggregator, data center bridging (DCB) features are auto-congured in standalone mode. You can display information on
DCB operation by using show commands.
NOTE: DCB features are not supported on an Aggregator in stacking mode.
Supported Modes
Standalone, Stacking, PMUX, VLT
Ethernet Enhancements in Data Center Bridging
DCB refers to a set of IEEE Ethernet enhancements that provide data centers with a single, robust, converged network to support
multiple trac types, including local area network (LAN), server, and storage trac. Through network consolidation, DCB results in
reduced operational cost, simplied management, and easy scalability by avoiding the need to deploy separate application-specic
networks.
For example, instead of deploying an Ethernet network for LAN trac, additional storage area networks (SANs) to ensure lossless
bre-channel trac, and a separate InniBand network for high-performance inter-processor computing within server clusters, only
one DCB-enabled network is required in a data center. The Dell Networking switches that support a unied fabric and consolidate
multiple network infrastructures use a single input/output (I/O) device called a converged network adapter (CNA).
A CNA is a computer input/output device that combines the functionality of a host bus adapter (HBA) with a network interface
controller (NIC). Multiple adapters on dierent devices for several trac types are no longer required.
Data center bridging satises the needs of the following types of data center trac in a unied fabric:
• LAN trac consists of a large number of ows that are generally insensitive to latency requirements, while certain applications,
such as streaming video, are more sensitive to latency. Ethernet functions as a best-eort network that may drop packets in
case of network congestion. IP networks rely on transport protocols (for example, TCP) for reliable data transmission with the
associated cost of greater processing overhead and performance impact.
• Storage trac based on Fibre Channel media uses the SCSI protocol for data transfer. This trac typically consists of large data
packets with a payload of 2K bytes that cannot recover from frame loss. To successfully transport storage trac, data center
Ethernet must provide no-drop service with lossless links.
• Servers use InterProcess Communication (IPC) trac within high-performance computing clusters to share information. Server
trac is extremely sensitive to latency requirements.
To ensure lossless delivery and latency-sensitive scheduling of storage and service trac and I/O convergence of LAN, storage, and
server trac over a unied fabric, IEEE data center bridging adds the following extensions to a classical Ethernet network:
• 802.1Qbb - Priority-based Flow Control (PFC)
• 802.1Qaz - Enhanced Transmission Selection (ETS)
• 802.1Qau - Congestion Notication
• Data Center Bridging Exchange (DCBx) protocol
NOTE: In Dell Networking OS version 9.4.0.x, only the PFC, ETS, and DCBx features are supported in data center
bridging.
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Data Center Bridging (DCB)