1. A method for configuring flow control among policy groups used in a network device processing a packet stream, the method comprising: (a) providing a configuration interface identifying a plurality of policy groups for configuring a network device, each policy group of the plurality of policy groups comprising one or more policies to be processed consecutively; (b) identifying, by the configuration interface, a policy of a first policy group of the plurality of policy groups, the policy specifying a rule comprising an expression; and (c) receiving, via the configuration interface, information identifying a second policy group of the plurality of policy groups to be processed based on an evaluation of the expression of the rule of the policy in the first policy group.