Setting the Maximum Number of Connections in an Eth-Trunk that Affects Spanning Tree Calculation
Context
The path costs affect spanning tree calculation. Changes to path costs trigger spanning tree recalculation. The path cost of an interface is affected by its bandwidth, so changes to the interface bandwidth also affect spanning tree calculation.
- Eth-Trunk 1 has higher bandwidth than Eth-Trunk 2. After STP calculation, Eth-Trunk 1 on SwitchB is selected as the root port and Eth-Trunk 2 is selected as the alternate port.
- If the maximum number of connections affecting bandwidth of Eth-Trunk 1 is set to 1, the path cost of Eth-Trunk 1 becomes larger than the path cost of Eth-Trunk 2. Therefore, the two devices perform spanning tree recalculation. Afterwards, Eth-Trunk 1 on SwitchB becomes the alternate port and Eth-Trunk 2 becomes the root port.
The maximum number of connections affects only the path cost of an Eth-Trunk interface participating in spanning tree calculation, and does not affect the actual bandwidth of the Eth-Trunk link. The actual bandwidth for an Eth-Trunk link depends on the number of active member interfaces in the Eth-Trunk.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
interface eth-trunk trunk-id
The Eth-Trunk interface view is displayed.
- Run:
max bandwidth-affected-linknumber link-number
The maximum number of connections affecting the Eth-Trunk bandwidth is set.
By default, the maximum number of connections affecting the bandwidth of an Eth-Trunk is 8.