David R. Cheriton

Using dynamic buffer limiting to protect against belligerent flows in high-speed networks

Conventional QoS mechanisms have focused primarily on providing better than normal service for some flows over others. With networks moving to much higher speeds and reasonable provisioning, best efforts access to network resources is adequate for common applications except when a belligerent flow attempts to consume an excessive amount of bandwidth. Any mechanism that attempts to contain such a flow must be able to operate at wirespeed in hardware. In this environment, conventional QoS mechanisms are not sufficient, either because they do not have mechanisms to contain these belligerent flows or because they are not practical to implement in hardware. In this paper we describe dynamic buffer limiting (DBL), a buffer and queue management mechanism designed to recognize and handle belligerent flows at very high speed and suitable for hardware implementation.