[Cake] [PATCH net-next v6] Add Common Applications Kept Enhanced (cake) qdisc

Cong Wang xiyou.wangcong at gmail.com
Mon Apr 30 17:21:06 EDT 2018

On Sun, Apr 29, 2018 at 2:34 PM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> sch_cake targets the home router use case and is intended to squeeze the
> most bandwidth and latency out of even the slowest ISP links and routers,
> while presenting an API simple enough that even an ISP can configure it.
> Example of use on a cable ISP uplink:
> tc qdisc add dev eth0 cake bandwidth 20Mbit nat docsis ack-filter
> To shape a cable download link (ifb and tc-mirred setup elided)
> tc qdisc add dev ifb0 cake bandwidth 200mbit nat docsis ingress wash
> CAKE is filled with:
> * A hybrid Codel/Blue AQM algorithm, "Cobalt", tied to an FQ_Codel
>   derived Flow Queuing system, which autoconfigures based on the bandwidth.
> * A novel "triple-isolate" mode (the default) which balances per-host
>   and per-flow FQ even through NAT.
> * An deficit based shaper, that can also be used in an unlimited mode.
> * 8 way set associative hashing to reduce flow collisions to a minimum.
> * A reasonable interpretation of various diffserv latency/loss tradeoffs.
> * Support for zeroing diffserv markings for entering and exiting traffic.
> * Support for interacting well with Docsis 3.0 shaper framing.
> * Extensive support for DSL framing types.
> * Support for ack filtering.

Why this TCP ACK filtering has to be built into CAKE qdisc rather than
an independent TC filter? Why other qdisc's can't use it?

> * Extensive statistics for measuring, loss, ecn markings, latency
>   variation.
> A paper describing the design of CAKE is available at
> https://arxiv.org/abs/1804.07617


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