Reference Guide

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Data Center Bridging (DCB)
Data center bridging (DCB) is supported on the S4820T platform.
NOTE:
DCB is not supported when you use 10GBaseT ports for stacking.
Ethernet Enhancements in Data Center Bridging
The following section describes DCB.
In the Dell Networking operating system (FTOS) version 8.3.12.0, the S4820T system supports loading two DCB_Config
files: FCoE_DCB_Config and iSCSI_DCB_Config .
These files are located in the root directory flash:/CONFIG_TEMPLATE. After copying the configuration files to the
startup config and reloading the system.
The S4820T supports the following DCB features:
• Data center bridging exchange protocol (DCBx)
• Priority-based flow control (PFC)
• Enhanced transmission selection (ETS)
DCB refers to a set of IEEE Ethernet enhancements that provide data centers with a single, robust, converged network to
support multiple traffic types, including local area network (LAN), server, and storage traffic. Through network
consolidation, DCB results in reduced operational cost, simplified management, and easy scalability by avoiding the
need to deploy separate application-specific networks.
For example, instead of deploying an Ethernet network for LAN traffic, include additional storage area networks (SANs)
to ensure lossless Fibre Channel traffic, and a separate InfiniBand 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 unified 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 different devices for several traffic types are no longer required.
Data center bridging satisfies the needs of the following types of data center traffic in a unified fabric:
LAN traffic LAN traffic consists of many flows that are insensitive to latency requirements, while certain
applications, such as streaming video, are more sensitive to latency. Ethernet functions as a
best-effort network that may drop packets in the 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 traffic Storage traffic based on Fibre Channel media uses the SCSI protocol for data transfer. This
traffic typically consists of large data packets with a payload of 2K bytes that cannot recover
from frame loss. To successfully transport storage traffic, data center Ethernet must provide
no-drop service with lossless links.
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