The tc-protection interval command sets the topology change protection interval at which topology change notification messages are sent.
The undo tc-protection interval command restores the default topology change protection interval.
By default, the topology change protection interval is 2s.
| Parameter | Description | Value |
|---|---|---|
| interval-value | Specifies the topology change protection interval. A longer interval ensures stable ERPS operation, but may cause slow convergence. |
The value is an integer that ranges from 1 to 600, in seconds. |
Usage Scenario
If a user terminal connects to an upper-layer network through multiple ERPS rings and the topology of the ERPS ring closest to the user terminal changes, topology change notifications will be multiplied by 2 each time they pass through a ring until they reach the upper-layer network. As a result, the upper-layer network receives many identical topology change notifications.
In addition, if an ERPS ring frequently receives topology change notifications, its nodes will have lower CPU processing capability and repeatedly update Flush-FDB packets, consuming much bandwidth. To prevent this problem, run the tc-protection interval command to set the topology change protection interval at which the maximum number of topology change notifications specified in the tc-protection threshold command are processed. Then, during the topology change protection interval, the device processes only the specified maximum number of topology change notification messages. If there are excess notifications, the device processes all the excess notifications once after the topology change protection interval elapses. For example, if the topology change protection interval is set to 10 seconds and the maximum number is set to 5, when a device receives topology change notifications, the device processes only the first 5 topology change notifications within 10 seconds and processes the subsequent topology change notifications only after 10s. This prevents the device from frequently deleting MAC address entries and ARP entries.
Prerequisites
The erps ring command has been executed to create an ERPS ring.
Precautions
Suppressing topology change notification transmission allows the upper-layer network to receive and process only one notification during the topology change protection interval and protects ERPS nodes against topology change (TC) attacks.