Qm-4-class_not_supported

rakem

I have this config on a 3550 switch:

L3-Switch(config-if)#do sh class-map
Class Map match-any class-default (id 0)
Match any

Class Map match-all web (id 1)
Match access-group 100

L3-Switch(config-if)#do sh policy-map
Policy Map web
Class web
set dscp af21


Trying to match any traffic from ACL 100 and set it to af21.

When i try to apply it to an interface i get:

L3-Switch(config-if)#service-policy output web
L3-Switch(config-if)#
00:16:52: %QM-4-CLASS_NOT_SUPPORTED: Classification is not supported in classmap web
00:16:52: %QM-4-CLASS_NOT_SUPPORTED: Classification is not supported in classmap web


Catalyst 3550 Multilayer Switch System Message Guide, 12.1(6)EA1 - Message and Recovery Procedures [Cisco Catalyst 3550 Series Switches] - Cisco Systems

That above link says on a 3550 i can only match on a dscp values.... is there an upgraded IOS that i can use to set dscp values on a 3550 or can it just not be done??

thanks