H3C Technologies H3C S10500 Series Switches - Manual (Page 37)

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Configuring VSANs
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.
• Providing services.
The VSAN technology delivers the following benefits:
• Improved security—VSANs are isolated from each other.
• Improved scalability—Each VSAN independently runs and provides services. Different VSANs can
use the same address space so that network scalability is improved.
• Flexibility—You can assign interfaces to different VSANs without changing the physical
connections of the SAN.
VSAN fundamentals
VFC interfaces in a VSAN 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. A 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 with 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.
Figure 16 shows a typical trunk VSAN.
• The F_Ports in blue on switches are configured as access ports and assigned to VSAN 1.
• The F_Ports in purple are configured as access ports and assigned to VSAN 2.
• The E_Ports are configured with trunk VSANs 1 and 2.
When servers read the disks, the N_Ports of different servers send FC frames without VFT_Headers to the
F_Ports on FC switch Switch A. Switch A searches for the outgoing interfaces in the FIB table of the VSAN
that each F_Port belongs to. These F_Ports use the same E_Port as the outgoing interface. When the
frames are forwarded out of the E_Port, they are tagged with the VFT_Header of VSAN 1 and VSAN 2.
Then, the frames travel across multiple VSAN-capable switches to the E_Port of FC switch Switch B.
According to the VFT_Headers, Switch B searches for the outgoing interfaces in the FIB tables of the
VSANs, and forwards them to the F_Ports. Then, the F_Ports remove the VFT_Headers and send the