When an ERPS-enabled interface has sub-interfaces bound to a BD or VSI, to allow the interface to immediately instruct these sub-interfaces to update their ARP and MAC address entries after the interface receives topology change (TC) packets, configure the TC change notification function on the interface.
In normal situations, when the topology of an ERPS ring changes and an interface receives TC packets, the ERPS ring reselects an interface for blocking, and accordingly all devices update their ARP and MAC address entries. However, if an ERPS-enabled interface has BD- or VSI-bound sub-interfaces, the sub-interfaces cannot detect the TC event immediately. As a result, other devices in the BD or VSI cannot be promptly instructed to update their ARP and MAC address entries. To prevent this problem, the TC change notification function can be configured on the ERPS-enabled interface. If the interface receives TC packets, the interface instructs its sub-interfaces to update their ARP and MAC address entries.