The last several years has seen a renewed interest in smart queue management to curb excessive network queueing delay, as people have realised the prevalence of bufferbloat in real networks. However, for an effective deployment at today's last mile connections, an improved queueing algorithm is not enough in itself, as often the bottleneck queue is situated in legacy systems that cannot be upgraded. In addition, features such as per-user fairness and the ability to de-prioritise background traffic are often desirable in a home gateway.In this paper we present Common Applications Kept Enhanced (CAKE), a comprehensive network queue management system designed specifically for home Internet gateways. CAKE packs several compelling features into an integrated solution, thus easing deployment. These features include: bandwidth shaping with overhead compensation for various link layers; reasonable DiffServ handling; improved flow hashing with both per-flow and per-host queueing fairness; and filtering of TCP ACKs. Our evaluation shows that these features offer compelling advantages, and that CAKE has the potential to significantly improve performance of last-mile internet connections.
As an alternative, queueing in the lower layers can be avoided by deploying a bandwidth shaper as part of the queue management system. By limiting the traffic traversing the bottleneck link to a bandwidth that is slightly less than the physical capacity of the link itself, queueing at the physical bottleneck can be eliminated and bufferbloat avoided. Such bandwidth shaping can be performed by a token bucket-based shaper (as is well-known from ATM networks, e.g., @cite_17 ), or by a rate-based shaper (which is known from video streaming applications, e.g., @cite_3 ).
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We introduce the concept of dynamic rate shaping, a technique to adapt the rate of compressed video bitstreams (MPEG-1, MPEG-2, H.261, as well as JPEG) to dynamically varying bit rate constraints. The approach provides an interface (or filter) between the encoder and the network, with which the encoder's output can be perfectly matched to the network's quality of service characteristics. Since the presented algorithms do not require interaction with the encoder, they are fully applicable to precoded, stored video (e.g., video-on-demand systems). By decoupling the encoder and the network, universal interoperability can be achieved. In essence, DRS bridges the gap between CBR and VBR video, allowing a continuum of possibilities between the two. A set of low-complexity algorithms for so-called unconstrained dynamic rate shaping are presented, and both optimal and extremely fast designs are discussed. Experimental results are provided using actual MPEG-2 bitstreams. The new asynchronous transfer mode (ATM) will be used for the information transport in the future broadband network. An important function of the ATM network is bandwidth enforcement or policing. The so-called ‘leaky bucket’ algorithm can be used to monitor and enforce the bit rate of a constant bit rate (CBR) connection. The parameters of the ‘leaky bucket’ algorithm depend on the bit rate of the connection and on the cell delay jitter. Sugestions for setting the parameters of the ‘leaky bucket’ algorithm are provided in this paper. Furthermore, a ‘dual leaky bucket’ algorithm is proposed to police the traffic parameters of a variable bit rate (VBR) connection. The ‘dual leaky bucket’ approach could also be used to define a VBR bearer service in the future broadband network.