Fabric OS Reference Manual

Telnet Commands 153

There are several things that occur when a port is configured as a multicast

loopback port:

• The green port LED will blink slowly, indicating a loopback state. If

optical GBIC is applied, the laser will be disabled and will not respond

to any attempt to connect to any device.

• The comment field of switchShow will show that it is looped back to

itself:

"port 3: sw No_Light Loopback->3"

• The portFlags line of portShow will display the “F_PORT” and

“INT_LB” flags:

"portFlags: 0x20249 PRESENT F_PORT U_PORT INT_LB LED"

• mcastShow will show the port as a member in its “Member Ports”

column.

Operands This command has the following operands:

portnumber

Specify the port number to be configured. Valid values

are 0-7 or 0-15 depending on the switch type. This

operand is required.

0|1

Specify the value 1 and the “portnumber” is dedicated

as a multicast loopback port. Specify the value 0 and

the “portnumber” is de-configured from its previous

role as a multicast loopback port. This operand is

required.

Example To configure switch port 3 as a multicast loopback port: