H3C Technologies H3C S12500-X Series Switches - Manual (Page 16)

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Figure 7 FPMA composition
How FCoE works
Figure 8 Block diagrams of the ENode and the FCF switch
NOTE:
This section describes how FCoE works only on the FCF switch, rather than on the ENode.
Procedure for receiving and sending FC frames over Ethernet
An FC frame is transmitted over Ethernet using the following workflow:
• FIP establishes a virtual link between the VFC interface of the FCF switch and the VN interface of the
ENode or between VFC interfaces of two FCF switches.
• After the virtual link is established, the FCF switch encapsulates the FC frame in an FCoE frame and
sends it out.
• After receiving the FCoE frame, the FCF switch removes its Ethernet header to send the original FC
frame to the upper layer for processing.
How FIP works
FIP sets up and maintains virtual links between a VFC interface and a VN interface or between VFC
interfaces.
Two categories of packets are used in FIP: Discovery Solicitation and Discovery Advertisement. There are
two types of Discovery Advertisement:
• Solicited Discovery Advertisement—A reply for a Discovery Solicitation.
• Unsolicited Discovery Advertisement—Periodically sent to advertise the presence of a virtual link or
maintain an existing virtual link.
The following example shows how a virtual link is set up between an FCF switch and an ENode.
Virtual link
ENode FCF
VN interface VFC interface
FC layer
Ethernet
layer
Ethernet
interface Ethernet
interface
FC layer
Ethernet
layer