The rate limit type to use with this control.
A value of none(1) indicates that no rate limit is set for
this control.
A value of receivePort(2) indicates that the configured rate
limit is applied on a per-port basis.
A value of aggregate(3) indicates that the configured rate
limit is aggregated across the set of ports that are configured
for the rate limit.
For values other than none(1), the rate limit entries are
created via the a3ComQosCtrlRateLimitTable.