H3C Technologies H3C S12500-X Series Switches - Manual (Page 15)

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Figure 6 FCoE network diagram
VFC interface and VN interface
A virtual fiber channel (VFC) interface is a logical interface manually created on the FCF switch to
simulate the function of a physical FC interface.
To use a VFC interface, bind it to a physical Ethernet interface.
You can connect either an ENode or an FCF switch to a VFC interface.
VFC interfaces support E mode, F mode (default), and NP mode.
The virtual node (VN) interface is a logical interface on an ENode to simulate the function of a physical
FC interface.
FIP protocol
FCoE initialization protocol (FIP) is an FCoE control protocol that establishes and maintains virtual links.
FIP establishes a virtual link between the VFC interface of an FCF switch and the VN interface of an
ENode or between VFC interfaces of two FCF switches to provide a physical infrastructure for
transmitting FC frames over Ethernet.
FCoE frames
To transmit an FC frame over an Ethernet link, you must encapsulate the FC frame in an FCoE frame by
adding an Ethernet frame header to the FC frame.
An FCoE frame uses Ethernet II encapsulation, which has the following fields in the Ethernet header:
• EtherType 0x8906.
• Destination MAC address/source MAC address—For a switch, it is the FCoE MAC address of the
switch (which can be displayed by using the display fcoe command). For a node, it is the fabric
provided MAC address (FPMA) of the node. As shown in Figure 7 , an FPMA is composed of the
FC-MAP as the 24 most significant bits and the FC ID of the VN interface as the 24 least significant
bits. The FC-MAP takes the value of the switch FC-MAP, 0x0EFC00 by default and configurable by
using the fcoe fcmap command.