Configuration Guide User guide

FastIron Configuration Guide 1107
53-1002494-02
STP feature configuration
NOTE
Use caution when changing the spanning tree priority. If the switch becomes the root bridge, Fast
Uplink Span will be disabled automatically.
Fast Uplink Span Rules for Trunk Groups
If you add a port to a Fast Uplink Span group that is a member of a trunk group, the following rules
apply:
• If you add the primary port of a trunk group to the Fast Uplink Span group, all other ports in the
trunk group are automatically included in the group. Similarly, if you remove the primary port in
a trunk group from the Fast Uplink Span group, the other ports in the trunk group are
automatically removed from the Fast Uplink Span group.
• You cannot add a subset of the ports in a trunk group to the Fast Uplink Span group. All ports
in a trunk group have the same Fast Uplink Span property, as they do for other port properties.
• If the working trunk group is partially down but not completely down, no switch-over to the
backup occurs. This behavior is the same as in the standard STP feature.
• If the working trunk group is completely down, a backup trunk group can go through an
accelerated transition only if the following are true:
• The trunk group is included in the fast uplink group.
• All other ports except those in this trunk group are either disabled or blocked. The
accelerated transition applies to all ports in this trunk group.
When the original working trunk group comes back (partially or fully), the transition back to the
original topology is accelerated if the conditions listed above are met.
Configuring a Fast Uplink Port Group
To configure a group of ports for Fast Uplink Span, enter the following commands:
Brocade(config)# fast uplink-span ethernet 4/1 to 4/4
Brocade(config)# write memory
Syntax: [no] fast uplink-span [ethernet <port> [ethernet <port>… | to <port>]]
Specify the port variable in one of the following formats:
• FWS, FCX, and ICX stackable switches – stack-unit/slotnum/portnum
• FSX 800 and FSX 1600 chassis devices – slotnum/portnum
• ICX devices – slotnum/portnum
• FESX compact switches – portnum
This example configures four ports, 4/1 – 4/4, as a Fast Uplink Span group. In this example, all
four ports are connected to a wiring closet switch. Only one of the links is expected to be active at
any time. The other links are redundant. For example, if the link on port 4/1 is the active link on
the wiring closet switch but becomes unavailable, one of the other links takes over. Because the
ports are configured in a Fast Uplink Span group, the STP convergence takes one second instead of
taking atleast 30 seconds using the standard STP forward delay.
You can add ports to a Fast Uplink Span group by entering the fast uplink-span command
additional times with additional ports. The device can have only one Fast Uplink Span group, so all
the ports you identify as Fast Uplink Span ports are members of the same group.