ZyXEL Communications ISG50-ISDN User Manual page 301

Chapter 14 Policy and Static Routes
When multiple policy routes require more bandwidth, the ISG50 gives the highest priority policy
routes the available bandwidth first (as much as they require, if there is enough available
bandwidth), and then to lower priority policy routes if there is still bandwidth available. The ISG50
distributes the available bandwidth equally among policy routes with the same priority level.
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ISG50 User's Guide