Installation guide

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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 4 shows how PFC works in a converged traffic scenario.
FIGURE 4 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 5. 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.
FIGURE 5 FCOE MAPPING ILLUSTRATION (SOURCE FC-BB-5 REV 2.0)
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