Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 267)

MAC aging interval is 5 minutes, the aging interval changes temporarily to the value of the forward
delay (for example, 15 seconds) in response to an STP topology change.
In normal STP, the accelerated cache aging occurs even when a single host goes up or down. Because
Fast Port Span does not send a topology change notification when a host on a Fast Port Span port
goes up or down, the unnecessary cache aging that can occur in these circumstances under normal
STP is eliminated.
Fast Port Span is a system-wide parameter and is enabled by default. Thus, when you boot a device, all
the ports that are attached only to end stations run Fast Port Span. For ports that are not eligible for
Fast Port Span, such as ports connected to other networking devices, the device automatically uses the
normal STP settings. If a port matches any of the following criteria, the port is ineligible for Fast Port
Span and uses normal STP instead:
• The port is 802.1Q tagged
• The port is a member of a trunk group
• The port has learned more than one active MAC address
• An STP Configuration BPDU has been received on the port, thus indicating the presence of another
bridge on the port.
You also can explicitly exclude individual ports from Fast Port Span if needed. For example, if the only
uplink ports for a wiring closet switch are Gbps ports, you can exclude the ports from Fast Port Span.
Disabling and re-enabling fast port span
Fast Port Span is a system-wide parameter and is enabled by default. Therefore, all ports that are
eligible for Fast Port Span use it.
To disable or re-enable Fast Port Span, enter the following commands.
device(config)#no fast port-span
device(config)#write memory
Syntax: [no] fast port-span
NOTE
The fast port-span command has additional parameters that let you exclude specific ports. These
parameters are shown in the following section.
To re-enable Fast Port Span, enter the following commands.
device(config)#fast port-span
device(config)#write memory
Excluding specific ports from fast port span
To exclude a port from Fast Port Span while leaving Fast Port Span enabled globally, enter commands
such as the following.
device(config)#fast port-span exclude ethernet 1
device(config)#write memory
To exclude a set of ports from Fast Port Span, enter commands such as the following.
device(config)#fast port-span exclude ethernet 1 ethernet 2 ethernet 3
device(config)#write memory
Disabling and re-enabling fast port span
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