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Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 1      Product Overview
New Technologies in the Cisco Nexus 5000 Series
IEEE 802.3x link-level flow control allows a congested receiver to signal the far end to pause the data 
transmission for a short period of time. The pause functionality is applied to all the traffic on the link. 
The priority flow control (PFC) feature applies pause functionality to specific classes of traffic on the 
Ethernet link. For example, PFC can provide lossless service for the FCoE traffic, and best-effort service 
for the standard Ethernet traffic. PFC can provide different levels of service to specific classes of 
Ethernet traffic (using IEEE 802.1p traffic classes).
I/O Consolidation
I/O consolidation (IOC) allows a single network technology to carry IP, SAN and IPC traffic. 
FCoE enables an evolutionary approach to IOC. The upper Fibre Channel layers are unchanged, so the 
Fibre Channel operational model is maintained. FCoE network management and configuration is similar 
to a native Fibre Channel network. 
Cisco Nexus 5000 Series switches use FCoE to carry Fibre Channel and Ethernet traffic on the same 
physical Ethernet connection between the switch and the server. At the server, the connection terminates 
to a converged network adapter (CNA) . The adapter presents two interfaces to the server’s operating 
system (OS): one Ethernet NIC interface and one Fibre Channel HBA interface. The server OS is not 
aware of the FCoE encapsulation (See Figure 1-1)
At the switch, the incoming Ethernet port separates the Ethernet and Fibre Channel traffic (using 
Ethertype to differentiate the frames). Ethernet frames and Fibre Channel frames are switched to their 
respective network-side interfaces. 
Cisco Nexus 5000 Series switches provide quality of service (QoS) capabilities to ensure lossless service 
across the switch for Fibre Channel traffic. Best-effort service can be applied to all of the Ethernet traffic 
or specific classes of Ethernet traffic can be configured with different QoS levels.
Figure 1-1 I/O Consolidation
FCoE
Adapter
10GE
NIC
FC
HBA
IP FC SAN
10GE
10GE
FC
IOC Switch
Server
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