Enabling STP/RSTP
Context
Before enabling STP/RSTP, ensure that you have performed all basic configurations, such as the device priority and port priority, on the device and its ports. After STP/RSTP is enabled on a ring network, spanning tree calculation starts immediately on the network. Making changes to configurations will affect spanning tree calculation and may cause network flapping.
Procedure
- Run system-view
The system view is displayed.
- Run stp enable
STP/RSTP is enabled on the device.
By default, STP/RSTP is enabled on a switch.
- Run commit
The configuration is committed.
Follow-up Procedure
When the topology of a spanning tree changes, the forwarding paths for associated VLANs are changed. Devices need to update the ARP entries corresponding to those VLANs. Depending on how devices process ARP entries, STP/RSTP convergence mode can be fast or normal.
In fast mode, ARP entries to be updated are directly deleted.
In normal mode, ARP entries to be updated are rapidly aged.
The remaining lifetime of ARP entries to be updated is set to 0 to immediately age the ARP entries out. If the number of ARP aging probes is greater than 0, the device performs aging probe for these ARP entries.
Run the stp converge { fast | normal } command in the system view to configure the STP/RSTP convergence mode.
By default, the normal STP/RSTP convergence mode is used. The normal mode is recommended. If the fast mode is used, ARP entries will be frequently deleted, causing a high CPU usage (even 100%). As a result, network flapping will frequently occur.