1. A method of providing packet routing information, the method comprising: encoding the packet routing information into a non-static compact representation of set membership; and putting the non-static compact representation of set membership into a header of a packet, wherein input parameters to compute the non-static compact representation of set membership include a packet-specific parameter or a flow-specific parameter, wherein the packet-specific parameter comprises a parameter unique to the packet with respect to a path of the packet, wherein the flow-specific parameter comprises a parameter unique to a particular flow of the packet, wherein the packet comprises a first packet, wherein the non-static compact representation comprises a first non-static compact representation, wherein the header comprises a first header comprising the first non-static compact representation, and wherein the method further comprises: transmitting, from a source node, the first packet comprising the first header comprising the first non-static compact representation, along the path; and transmitting, from the source node, a second packet comprising a second header comprising a second non-static compact representation different from the first non-static compact representation, along the path.