Enabling MSTP
Context
After MSTP multi-process is enabled on the switch, you must enable MSTP in the MSTP process view so that the MSTP configuration can take effect in the MSTP process.
Enabling MSTP on a ring network immediately triggers spanning tree calculation on the network. On the switch, configurations such as the switch priority and port priority affect spanning tree calculation. Any change to these configurations may cause network flapping. Therefore, to ensure rapid and stable spanning tree calculation, perform basic configurations on the switch and its ports and enable MSTP.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
stp process process-id
The view of the created MSTP process is displayed.
- Run:
stp enableMSTP is enabled on the MSTP process of the device.
By default, the MSTP function is enabled on the device.
Follow-up Procedure
If the topology of a spanning tree changes, the forwarding paths to associated VLANs are changed. On the switch, therefore, the ARP entries corresponding to these VLANs need to be updated. MSTP processes ARP entries in either fast or normal mode.
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. The switch rapidly processes these aged entries. If the number of ARP aging probe attempts is not set to 0, ARP implements aging probe for these ARP entries.
In either fast or normal mode, MAC entries are directly deleted.
To specify which mode is used for STP/RSTP convergence, run the stp converge { fast | normal } command in the system view.
By default, the normal MSTP convergence mode is used.
If fast mode is used, ARP entries are frequently deleted. This causes high CPU usage on the MPU and LPU (reaching 100%) and results in frequent network flapping. Therefore, using normal mode is recommended.