ance of a Linux Implementation of Class Based
K.J. Loh, Irwin Gui, K.C. Chua · 1998
Class Based Queueing (CBQ) is a link-sharing and resource management mechanism for packet networks. We have ported the CBQ implementation on FreeBSD, also known as Alternate Queueing (ALTQ), to the Linux platform. This paper investigates the pelformance of CBQ in terms of latency, bandwidth guarantee and delay. CBQ is found to be able to preserve bandwidth allocated to the classes. Howevel; it does not scale well with the number of data flows as it incurs additional delay with each new data $ow admitted. Due to this additional delay, the admission control cannot predict the delay experienced by the existing $ows after admitting a new $ow. Although CBQ is able to provide lower delay to higher priorityjows, it also introduces jitter to the traflc owing to its packet scheduling artifact. As such, CBQ is not suitable forfine-grained scheduling of real-time traflc. It is more suited for providing bandwidth guarantee to aggregated datajows.