Communication flow, Vsan – H3C Technologies H3C S10500 Series Switches User Manual
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Communication flow
FC switches provide data transmission services. Through FC switches, a server sends instructions and
data to disk devices and reads data from disk devices.
Figure 4 FC SAN communication model
The following takes a server accessing a disk device as an example to see how data communication
occurs in an FC SAN.
1.
The server and the disk device send fabric login (FLOGI) packets to register with the FC switches.
Then, the FC switches assign FC addresses to each directly-connected node.
A FLOGI packet contains information that includes the port WWN, node WWN, and the
expected FC address.
2.
The registered server and disk device send name service registration requests to their respective
access FC switches to register name service information, including FC4 information. Finally, each
FC switch in the fabric stores the name service information of all nodes. For more information
Configuring and obtaining FC4 information of nodes
3.
To access a disk device, the server must obtain the list of disk devices in the fabric and their
WWNs and FC addresses. For this purpose, the server must send a name service query request to
its directly-connected FC switch.
4.
After the server obtains the FC address of the disk device, the server can send FC frames destined
to the FC address to the FC switch nearby.
5.
When the FC switch receives the FC frame from the server, it performs the following operations:
{
Queries its FIB table for a data forwarding path according to the destination FC address.
{
Forwards the FC frame to the next-hop FC switch.
6.
The next-hop FC switch forwards the FC frame in the same way, until the FC switch at the last hop
forwards the FC frame to the destination disk device.
NOTE:
A FIB table is generated by the FC switch through calculation based on the FC routing protocol or
configured static routes.
VSAN
In actual applications, the data is insecure if the data of all users is transmitted in the same FC SAN. You
can divide one physical FC SAN into multiple virtual storage area networks (VSANs). VSANs are
separated from one another and provide independent services. This enhances adaptability and security
of the network and offers more effective services for users. For more information about VSANs, see
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