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• Path Cost (1-200000000) -- Amount the LAG contributes to the root path cost. The path cost is adjusted to a
higher or lower value, and is used to forward traffic when a path being rerouted. The path cost has a value of
1 to 200000000. If the path cost method is short, the LAG cost default value is 4. If the path cost method is
long, the LAG cost default value is 20000.
• Default Path Cost -- When selected, the LAG path cost returns to its default value.
• Priority (0-240, in steps of 16) -- Priority value of the LAG. The priority value influences the LAG choice when
a bridge has two looped ports. The priority value is between 0-240, in increments of 16.
• Designated Bridge ID -- The bridge priority and the MAC Address of the designated bridge.
• Designated Port ID -- The port priority and interface number of the designated port.
• Designated Cost -- The cost of the designated bridge.
• Forward Transitions -- Number of times the LAG State has changed from the Blocking state to a Forwarding
state.
Rapid Spanning Tree
While Classic Spanning Tree guarantees preventing L2 forwarding loops in a general network topology, convergence can
take up to 30-60 seconds. The convergence time is considered too long for many applications. When network topology
allows, faster convergence may be possible. The Rapid Spanning Tree Protocol (RSTP) detects and uses of network
topologies that provide faster convergence of the spanning tree, without creating forwarding loops.
RSTP has the following different port states:
• Disabled
• Learning
• Discarding
• Forwarding
Rapid Spanning Tree is enabled on the STP Global Settings page.
To open Rapid Spanning Tree screen perform the folling:
1.
Click Switch -> Spanning Tree -> Rapid Spanning Tree
2.
The Rapid Spanning Tree screen is displayed as in Figure 3-61
ú Listening -- The LAG is in the listening mode and cannot forward traffic or learn MAC
addresses.
ú Learning -- The LAG is in the learning mode and cannot forward traffic, but it can learn new
MAC addresses.
ú Forwarding -- The LAG is currently in the forwarding mode, and it can forward traffic and
learn new MAC addresses.
ú Broken -- The LAG is currently malfunctioning and cannot be used for forwarding traffic.
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