Method and apparatus for routing packets that have ordering requirements

A method of routing packets includes receiving a first packet, where the first packet has a first ordering requirement with respect to a prior packet that was received before the first packet, allocating a first entry that corresponds to the first packet in a scheduler, where the first entry includes a first indication of the first ordering requirement, and in response to the first indication, selecting the first entry corresponding to the first packet if one or more first resources used by the first packet and one or more second resources that are used by the prior packet but not by the first packet are available. As long as older entries whose resources are available are selected before newer entries, the first entry will be selected after the prior packet's entry due to the inclusion of the first indication in the first entry.