Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 153)

Multi-Service IronWare Switching Configuration Guide 123
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Configuring a LAG
5
Specifying the LAG threshold
Trunk threshold brings the LAG down if the trunk threshold condition is not met by the LAG.
Syntax: [no] trunk-threshold number
You can specify a threshold from 1 (the default) up to the number of ports in the LAG.
NOTE
This configuration is only applicable for configuration of a static or dynamic LAG.
Below are the different behavioral patterns for static and dynamic LAG.
Static LAG behavior
You can configure the Brocade device to disable all of the ports in a LAG when the number of active
member ports drops below a specified threshold value. For example, if a LAG has 8 ports, and the
threshold for the LAG is 5, then the LAG is disabled if the number of available ports in the LAG
drops below 5. If the LAG is disabled, then traffic is forwarded over a different link or LAG.
For example, the following commands establish a LAG consisting of four ports, and then establish a
threshold of three ports for this LAG.
Brocade(config)# lag blue static
Brocade(config-lag-blue)# ports ethernet 3/1 to 3/4
Brocade(config-lag-blue)# trunk-threshold 3
In this example, if the number of active ports drops below three, then all the ports are disabled in
the LAG.
When a LAG is down because of not meeting the LAG condition, the LAG is kept intact and it is
re-enabled if enough ports become active to reach the threshold.
NOTE
The trunk-threshold command should be configured only at one end of the trunk. If it is set on both
sides, link failures result in race conditions and change in functionality.
Dynamic LAG behavior
Unlike in static LAGs, if the number of active ports in a dynamic LAG falls below the threshold value,
the ports are logically blocked and out-of-sync is signaled on all the active member ports in that
LAG until it satisfies the trunk threshold condition again.
For example, the following commands establish a LAG consisting of four ports, and then sets a
threshold of three ports.
Brocade(config)# lag red dynamic
Brocade(config-lag-blue)# ports ethernet 3/1 to 3/4
Brocade(config-lag-blue)# trunk-threshold 3
In this example, if the number of active ports drops below 3, then all the ports in the LAG are
logically blocked. An out-of-sync is signaled on all the active member ports in that LAG until it
satisfies the trunk threshold condition again.
NOTE
Configure the same LACP Trunk threshold value on both sides of the LAG for better performance or
for connecting to the third-party devices.