Storm control on Cisco 6509

[l-gu]

On Cisco 6509 sup2, Version 12.1(13)E9, I want to configure command about storm-control broadcast and unicast level, but both two levels must be the same, why?

[l-gu]

I think, there's a storm control command bug on Cisco 6509, that both broadcast and unicast storm control level values must be same. When change unicast storm control level to the specified value, so broadcast storm level also become the value.

From Cisco 6509 manual, I can't find any information about this limitation.