H3C Technologies H3C S12500-X Series Switches - Manual (Page 64)

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Configuring VSAN
Overview
The virtual storage area network (VSAN) technology breaks a physical SAN into multiple VSANs, and
provides more secure, reliable, and flexible services.
Devices in a VSAN cannot get information about any other VSAN and devices in any other VSAN. Each
VSAN performs the following operations independently: selecting a principal switch, assigning domain
IDs, running routing protocols, maintaining routing table and FIB table, and providing services.
The VSAN technology delivers the following benefits:
• Improved security—VSANs are isolated from each other.
• Improved adaptability—Each VSAN independently runs and provides services. Different VSANs
can use the same address space so that network capacity is improved.
• Flexibility—You can assign interfaces to different VSANs without changing the physical
connections of the SAN.
VSAN fundamentals
VFC interfaces can only work as trunk ports. A trunk port can belong to multiple VSANs.
Trunk VSAN in an FC network
The trunk VSAN technology implements logical isolation among VSANs. The trunk VSAN works as
follows: The trunk VSAN adds a Virtual Fabric Tagging Header (VFT_Header, also known as VSAN tag)
to the FC frames. The VFT_Header contains a VF_ID (also known as "VSAN ID") field to indicate the
VSAN of the FC frames. In this way, FC frames within different VF_IDs are contained in their respective
VSANs, and different VSANs cannot communicate with each other. The trunk VSAN implements physical
connectivity and logical isolation in the 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 need to 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 VSAN trunk
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.