Product specifications

Deploying a Converged Storage Network Using a Cisco FCoE Switch
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ETS and DCBX simplify the management of DCB nodes significantly, especially when deployed
end-to-end in a converged data center. The DCBX protocol uses Link Layer Discovery Protocol
(LLDP) defined by IEEE 802.1AB to exchange and discover DCB capabilities.
Priority Flow Control
A fundamental requirement for a high-performance storage network is guaranteed data delivery. This
requirement must be satisfied to transport critical storage data on a converged Ethernet network with
minimum latency. Another critical enhancement to conventional Ethernet is lossless Ethernet. IEEE
802.3X PAUSE defines how to pause link traffic at a congestion point to avoid packet drop. IEEE
802.1Qbb defines Priority Flow Control (PFC), which is based on IEEE 802.3X PAUSE and provides
greater control of traffic flow. PFC eliminates lost frames caused by congestion. PFC enables the
pausing of less-sensitive data classes, while not affecting traditional LAN protocols operating through
different priority classes.
Figure 5 shows how PFC works in a converged traffic scenario.
FIGURE 5 PRIORITY FLOW CONTROL
Fibre Channel over Ethernet (FCoE)
FCoE is an ANSI T11 standard for the encapsulation of a complete Fibre Channel frame into an
Ethernet frame. The resulting Ethernet frame is transported over Enhanced Ethernet networks, as
shown in Figure 6. Compared to other mapping technologies, FCoE has the least mapping overhead
and maintains the same constructs as native Fibre Channel, thus operating with native Fibre Channel
management software. FCoE is based on lossless Ethernet to enable buffer-to-buffer credit
management and flow control of Fibre Channel packets.