Technical data

52 Brocade MLX Series and NetIron Family Documentation Updates
53-1002805-03
STP feature configuration
1
You can use the Fast Uplink Span feature on a Brocade device deployed as a wiring closet switch to
decrease the convergence time for the uplink ports to another device to just one second. The new
Uplink port directly goes to forward mode (bypassing listening and learning modes). The wiring
closet switch must be a Brocade device but the device at the other end of the link can be a Brocade
device or another vendor’s switch.
Configuration of the Fast Uplink Span feature takes place entirely on the Brocade device. To
configure the Fast Uplink Span feature, specify a group of ports that have redundant uplinks on the
wiring closet switch (Brocade device). If the active link becomes unavailable, the Fast Uplink Span
feature transitions the forwarding to one of the other redundant uplink ports in just one second. All
Fast Uplink Span-enabled ports are members of a single Fast Uplink Span group.
NOTE
To avoid the potential for temporary bridging loops, Brocade recommends that you use the Fast
Uplink feature only for wiring closet switches (switches at the edge of the network cloud). In
addition, enable the feature only on a group of ports intended for redundancy, so that at any given
time only one of the ports is expected to be in the forwarding state.
NOTE
When the wiring closet switch (Brocade device) first comes up or when STP is first enabled, the
uplink ports still must go through the standard STP state transition without any acceleration. This
behavior guards against temporary routing loops as the switch tries to determine the states for all
the ports. Fast Uplink Span acceleration applies only when a working uplink becomes unavailable.
Active uplink port failure
The active uplink port is the port elected as the root port using the standard STP rules. All other
ports in the group are redundant uplink ports. If an active uplink port becomes unavailable, Fast
Uplink Span transitions the forwarding of traffic to one of the redundant ports in the Fast Uplink
Span group in one second bypassing listening and learning port states.
Switchover to the active uplink port
When a failed active uplink port becomes available again, switchover from the redundant port to
the active uplink port is delayed by 30 seconds. The delay allows the remote port to transition to
forwarding mode using the standard STP rules. After 30 seconds, the blocked active uplink port
begins forwarding in just one second and the redundant port is blocked.
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.