Configuring the Maximum Number of Connections in an Eth-Trunk that Affects Spanning Tree Calculation
Context
Path costs are a major factor in spanning tree calculation and changing path costs triggers spanning tree recalculation. The path cost of an interface is affected by its bandwidth, so you can change the interface bandwidth to 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 is larger than the path cost of Eth-Trunk 2. Therefore, after the two devices perform spanning tree recalculation, 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-view
The 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 on the CE12800E equipped with ED-E/EG-E/EGA-E series cards is 128. For the CE12800E equipped with FD-X series cards and CE12800 series switches, the upper threshold for the number of interfaces that determine the bandwidth of an Eth-Trunk depends on the maximum number of configured LAGs.
- Run commit
The configuration is committed.