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DCB enables Ethernet fabrics to support lossless transmission to increase network scalability, support I/O
consolidation, ease management of multiple traffic flows, and optimize performance. Although SAN
consolidation requires only the lossless fabric provided by the Ethernet Pause mechanism, the Cisco
Nexus 5500 platform provides additional features that create an even more easily managed, high-
performance, unified network fabric. DCB features are summarized in Table 4 and supported by the Cisco
Nexus 5500 platform.
Table 4.
DCB Features and Benefits
Feature
Business Benefit
Priority Flow Control (PFC)
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Simplifies management of multiple traffic flows over a single network link
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Creates lossless behavior for Ethernet by allowing class-of-service (CoS)-based flow control
Enhanced Transmission Selection
(ETS)
Enables consistent management of quality of service (QoS) at the network level by providing consistent
scheduling of different traffic types (IP, storage, etc.)
Data Center Bridging Exchange
(DCBX) Protocol
Simplifies network deployment and reduces configuration errors by providing auto negotiation of DCB
features between the NIC and the switch and between switches
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FCoE is a standards-based upper-layer protocol that maps the Fibre Channel Protocol (FCP) and services
onto Layer 2 Ethernet. It is a straightforward encapsulation of Fibre Channel within Ethernet that preserves
existing Fibre Channel network management models and tools, helping protect investments in software
and staff training.
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Cisco unified fabric consolidates all data center I/O onto Layer 2 Ethernet. Unified fabric reduces capital
and operating costs by reducing the number of server adapters, cables, and upstream switches needed. All
I/O (LAN, SAN, and cluster) typically is consolidated onto two Ethernet links. DCB and FCoE enable the
incorporation of Fibre Channel frames into a unified fabric, facilitating wire-once strategies in which all
servers become capable of SAN connection. A standard and uniform approach to I/O enhances server and
storage consolidation strategies. The Cisco Nexus 5500 platform also connects to existing native Fibre
Channel networks, protecting current investments in storage networks. Additionally, the Cisco Nexus 5500
platform attaches to directly connected FCoE and Fibre Channel storage devices and supports multi-tiered
unified network fabric connect directly over FCoE.
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Unified ports allow any capable port to take on the character of 1 and 10 Gigabit Ethernet, SAN and LAN
shared on 10 Gigabit Ethernet, or 8/4/2/1-Gbps Fibre Channel. Unified ports give the user flexibility in
choosing SAN and LAN port options consistent with the virtualized data center and offer a migration path to
FCoE for those users not yet ready to make the move from native Fibre Channel.
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Energy efficiency achieved through the use of the Cisco Nexus 5500 platform helps data centers operate
within their space, power, and cooling parameters while reducing their carbon footprints. Every network link
at the rack level requires adapters, switches, and transceivers, all of which consume power. I/O
consolidation reduces energy consumption by eliminating the need for separate Fibre Channel adapters,
cables, and switches. In many cases, server cluster networks also can be consolidated onto 10 Gigabit
Ethernet networks, especially given the low latency of the Cisco Nexus 5500 platform. The switch hardware
is also designed for energy efficiency. Variable-speed fans consume only the amount of power necessary
to cool the chassis at that specific point in time. The switch power supplies are sized to support worst-case
scenarios, in which inefficient SFP+ transceivers increase power draw; however, when low-power cabling
solutions are deployed, the switch platform’s power supplies maintain 90 percent efficiency at only 25
percent utilization, making efficient use of power in best-case scenarios.
