H3C Technologies H3C S10500 Series Switches - Manual (Page 44)

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2. Before the PSST times out, the switches exchange packets carrying the principal switch information
to select a principal switch. On receiving such a packet, a switch compares the priority and WWN
of the principal switch carried in the packet against those locally recorded. The switch replaces the
locally-recorded principal switch information with the information recorded in the packet. It notifies
the other switches when any of the following conditions exist:
{
The priority carried in the packet is higher.
{
The priority in the packet is the same and the WWN is smaller.
Finally, all switches in the network make an agreement on the principal switch.
3. When the PSST times out, if the locally-recorded principal switch information is the local switch, the
switch becomes the principal switch.
After the principal switch is selected, the WWN of the principal switch becomes the fabric name.
NOTE:
During the process, if a switch receives a packet that updates the principal switch information, the switch
must record the E_Port receiving the packet. The link relevant to this E_Port is called the "upstream
principal link."
Domain ID assignment
A domain represents a switch and all N_Ports connected to the switch. Each domain must have a domain
ID.
Domain IDs can be manually configured or automatically assigned for FCF switches.
• When you manually configure static domain IDs, you must assign a unique domain ID to each
switch in the fabric.
• When domain IDs are dynamically assigned, the fabric configuration process is performed to select
a principal switch and assign domain IDs. After the principal switch is selected, the principal switch
assigns domain IDs to all switches in the fabric. After the fabric configuration process, each switch
has a unique domain ID.
The dynamic domain ID assignment process is as follows:
1. The principal switch assigns a domain ID to itself.
{
If you have configured a domain ID on the principal switch, the principal switch assigns itself the
configured domain ID.
{
If you have not configured a domain ID on the principal switch, the principal switch assigns itself
the smallest available domain ID.
2. The principal switch notifies its downstream switches to request domain IDs from it.
3. A downstream switch requests a domain ID from the principal switch.
If the downstream switch is configured with a domain ID, it requests the configured domain ID from
the principal switch.
4. The principal switch assigns a domain ID according to the following rules:
{
If the downstream switch requests a desired domain ID that is available, the principal switch
assigns the domain ID to the downstream switch.
{
The principal switch assigns the smallest available domain ID to the downstream switch when
one of the following conditions exists:
− The downstream switch does not request a desired domain ID.