A buffer stores only packets in one or more high-priority traffic flows in a first portion. The size of the first portion is determined based on an estimated maximum volume of traffic in the at least one high-priority traffic flow. The buffer stores packets in either the one or more high-priority traffic flows or one or more low-priority traffic flows in a second portion. The buffer stores only packets in the one or more low-priority traffic flows in a third portion. A processor marks the packets in the first portion and the second portion with a high-priority color prior to transmission of the packets. The processor marks the packets in the third portion with a low-priority color prior to transmission of the packets.