Technical data

Fabric OS Administrator’s Guide 2-15
Publication Number: 53-0000518-09
Working With Domain IDs
2
Connecting to Devices
To minimize port logins, power off all devices before connecting them to the switch. For devices that
cannot be powered off, first use the portDisable command to disable the port on the switch, and then
connect the device. When powering the devices back on, wait for each device to complete the fabric
login before powering on the next one.
Connecting to Other Switches
Refer to the hardware user’s guide of your specific switch for interswitch link (ISL) connection and
cable management information. The standard (default) ISL mode is L0, which you can configure with
the portCfgLongDistance command. ISL Mode L0 is a static mode, with the following maximum ISL
distances:
• 10 km at 1 Gbit/second
• 5 km at 2 Gbit/second
• 2.5 km at 4 Gbit/second
ISL mode L0 is available on all Fabric OS releases. When you upgrade from Fabric OS v4.0.0 to Fabric
4.1.0 or later, all extended ISL ports are set automatically to L0 mode.
For information on extended ISL modes, which enable longer distance interswitch links, refer to
Chapter 11, “Administering Extended Fabrics”.
Working With Domain IDs
Although domain IDs are assigned dynamically when a switch is enabled, you can reset them manually
so that you can control the ID number or to resolve a domain ID conflict when you merge fabrics.
If a switch already has a domain ID when it is enabled, and that domain ID conflicts with a switch
already in the fabric, the conflict is automatically resolved. The process can take several seconds, during
which time traffic is delayed.
The default domain ID for SilkWorm switches is 1.
The default domain ID applies to the logical switches in SilkWorm 12000, 24000, and 48000 directors
that are configured for two domains. To prevent domain conflict, you can either disable one of the
switches until the other is connected to the fabric, then reenable the switches so that unique domain IDs
are automatically assigned, or you can use the procedure “To set the domain ID” on page 2-16 to make
the domain IDs unique before connecting the logical switches to the fabric.
C
aution
On switches running Fabric OS v4.0.0 and later, do not use domain ID 0, which is reserved for
another purpose. The use of this domain ID can cause the switch to reboot continuously.
Avoid changing the domain ID on the FCS in secure mode. To minimize down time, change the domain
IDs on the other switches in the secure fabric.