According to certain embodiments, a system comprises one or more processors and one or more computer-readable non-transitory storage media comprising instructions that, when executed by the one or more processors, cause one or more components of the system to perform operations. The operations comprise receiving a packet comprising a source address; selecting an uplink for the packet, the uplink selected from a plurality of uplinks based on an uplink selection policy; determining whether the source address is valid on the selected uplink; determining whether to keep or re-write the source address based on whether the source address is valid on the selected uplink; keeping the source address when the source address is valid on the selected uplink or re-writing the source address when the source address is not valid on the selected uplink; and sending the packet to the selected uplink.