Packets are matched against flow entries based on prioritization. An entry that specifies an exact match (that is, no wildcards) is always the highest priority. All wildcard entries have a priority associated with them. Higher priority entries must match before the lower priority ones. If multiple entries have the same priority, the switch is free to choose any ordering. Higher numbers have higher priorities. The following figure shows the packet flow in an OpenFlow switch. It is important to note that if a flow table field has a value of any (* or wildcard), it matches all the possible values in the header.