[Cake] Getting Cake to work better with Steam and similar applications

Andy Furniss adf.lists at gmail.com
Sat Apr 22 12:38:21 EDT 2017

Andy Furniss wrote:
> Andy Furniss wrote:
>> Jonathan Morton wrote:
>>>>> So please add “atm overhead 32" to cake on eth0 or “atm 
>>>>> overhead 40” to cake instances on pppoe (these packets do not
>>>>> have the PPPoE header added yet and hence appear 8 bytes to
>>>>> small).
>>>> Thanks for your help, will definitely use them. Just wondering 
>>>> if I use "pppoe-vcmux/bridged-llcsnap" on eth0 or 
>>>> "pppoe-llcsnap" on pppoe0 would have the same effect? Or are 
>>>> there some other "under-the-hood" changes when using them?
>>> On the pppoe interface, use pppoe-vcmux if your modem is set to 
>>> use VC-MUX, or pppoe-llcsnap if it’s set to use LLC-SNAP (they 
>>> might be described using slightly different terms, but should 
>>> still be recognisable as one or the other).  This probably 
>>> depends on your ISP, and may further vary regionally within the 
>>> same ISP.
>>> I really prefer to use the self-explanatory keywords (which is 
>>> why I added them in the first place) instead of opaque magic 
>>> numbers. This is a point on which Sebastian has long disagreed 
>>> with me.
>> Either way (or maybe not!), what about the observation that 
>> attaching cake on pppoe, for me at least, required the use of the 
>> raw param due to the "auto compensation" mechanism seeing pppoe as 
>> +8 when the actual packets are just ip len so not +8.
> My case is not atm though, perhaps the atm param cancels out all 
> other auto overhead compensation?

Though that wouldn't really make sense for other use cases like shaping
on a real eth for some remote atm link.

Checking my not atm pppoe it seems without the raw param I would
actually be 14 + 8 bytes wrong.

tc qdisc add dev ppp0 handle 1:0 root cake bandwidth 19690kbit raw
overhead 34 diffserv4 dual-srchost nat rtt 200ms

results in -

qdisc cake 1: root refcnt 2 bandwidth 19690Kbit diffserv4 dual-srchost
nat rtt 200.0ms noatm overhead 56 via-ethernet

Random rambling on dual-srchost vs default triple - if I were to shape
ingress, which I don't because my ISP does it again now, I think
dual-srchost would be better in practice for home use. This being
because the CDNs of youtube or TV streamers - well blippers :-) like the
BBC netflix etc. may well mean that users that should be separate get
somehow lumped together - basically any assertion that it's rare for
different users to be downloading from the same remote server doesn't
really apply to streaming services.

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