Configuration Guide User guide

560 FastIron Configuration Guide
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Changing the MAC age time and disabling MAC address learning
Changing the MAC age time and disabling MAC
address learning
To change the MAC address age timer, enter a command such as the following.
Brocade(config)#mac-age-time 60
Syntax: [no] mac-age-time <secs>
<secs> specifies the number of seconds. Possible values differ depending on the version of
software running on your device, as follows:
• On FastIron WS and Brocade FCX Series devices, learned MAC address entries do not age out
until they are unused for 300 – 600 seconds. If necessary, you can change the MAC address
age timer to 0 or a value from 60 – 600 (seconds), in 60-second intervals. For example, you
can specify 60 or 120, but not 100. If you set the MAC age time to 0, aging is disabled.
• On FastIron X Series devices, you can configure 0 or a value from 10 – 86,400 (seconds), in
10-second intervals. If you set the MAC age time to 0, aging is disabled.
• On ICX devices, you can configure a value between 0 to 570 seconds.
NOTE: Usually, the actual MAC age time is from one to two times the configured value. For
example, if you set the MAC age timer to 60 seconds, learned MAC entries age out after remaining
unused for between 60 – 120 seconds. However, if all of the following conditions are met, then the
MAC entries age out after a longer than expected duration:
• The MAC age timer is greater than 630 seconds.
• The number of MAC entries is over 6000.
• All MAC entries are learned from the same packet processor.
• All MAC entries age out at the same time.
Disabling the automatic learning of MAC addresses
By default, when a packet with an unknown Source MAC address is received on a port, the Brocade
device learns this MAC address on the port.
You can prevent a physical port from learning MAC addresses by entering the following command.
Brocade(config)#interface ethernet 3/1
Brocade(config-if-e1000-3/1)#mac-learn-disable
Syntax: [no] mac-learn disable
Use the no form of the command to allow a physical port to learn MAC addresses.
MAC address learning configuration notes and feature limitations
• This command is not available on virtual routing interfaces. Also, if this command is configured
on the primary port of a trunk, MAC address learning will be disabled on all the ports in the
trunk.
• Entering the mac-learn-disable command on tagged ports disables MAC learning for that port
in all VLANs to which that port is a member. For example, if tagged port 3/1 is a member of
VLAN 10, 20, and 30 and you issue the mac-learn-disable command on port 3/1, port 3/1 will
not learn MAC addresses, even if it is a member of VLAN 10, 20, and 30.