H3C Technologies H3C S5830V2 Series Switches - Manual (Page 40)

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Figure 17 Trunk VSAN network
During the transmission process, VFT_Headers are added to and removed from the frames. A switch can
use the same physical interface to support multiple VSANs. The trunk VSAN technology reduces the
number of physical connections, actually implementing logical isolation in a physical network.
Trunk VSAN in an FCoE network
FCoE carries FC over Ethernet. In an FCoE network, VSANs in FC must be mapped to VLANs as
configured by the user, and the FIB table for a VSAN is also stored on the relevant VLAN. FCoE frames
use VLAN_Header in place of VFT_Header in FC frames and are forwarded based on the VLAN ID in
VLAN_Header.
A VFC interface can only work as a trunk port. The bound Ethernet interface must also be configured as
a trunk port, and its trunk VLAN list must include the VLANs mapped to each VSAN in the trunk VSAN
list of the VFC interface. An FCoE frame transmitted from a VFC interface can use the VLAN ID in
VLAN_Header to identify the VLAN to which it belongs.
VSAN mode negotiation
FC interfaces can work as access ports or trunk ports, depending on link negotiation. VFC interfaces can
only work as trunk ports and do not require negotiation.
Link negotiation involves a series of protocols. The Exchange Virtual Fabrics Parameters (EVFP) protocol
determines the VSAN mode that applies.
The EVFP negotiation determines the VSAN mode based on the following settings on both ends of a link:
• Trunk mode—The trunk mode can be Auto (default), On, or Off.
• Access VSAN—Indicates the VSAN to which the interface is added as an access port, which is
VSAN 1 by default.
• Trunk VSAN list—Indicates the VSANs to which the interface is added as a trunk port. By default,
the VSAN list is empty.
The EVFP negotiation process is as follows:
1. The interface at each end sends its trunk mode, access VSAN, and trunk VSAN list to the peer.
2. The two ends negotiate the VSAN tagging mode according to the trunk modes.
Table 3 shows the negotiation rules.
F_Port
F_Port
F_Port
F_Port
N_Port
N_Port N_Port
N_Port
VSAN 1
E_Port E_Port
VSAN 1
VSAN 2 VSAN 2
FC Fabric
Server A
Server B
Disk A
Disk B
FC switch B FC switch A