The ipv6 nd rs send rate-limit command configures a rate limit for sending ND RS messages on an interface, that is, the maximum number of ND RS messages that can be sent per second.
The undo ipv6 nd rs send rate-limit command restores the default configuration.
By default, the rate limit for sending ND RS messages is not configured on an interface, and ND RS messages are sent at a globally configured rate limit.