[Cake] cake/tc - removal of atm/ptm/ethernet specific overhead keywords

Jonathan Morton chromatix99 at gmail.com
Thu Jun 2 11:10:06 EDT 2016

> On 2 Jun, 2016, at 17:59, moeller0 <moeller0 at gmx.de> wrote:
> As I tried to convey before the matter is far from simple. For example my ISP, DTAG, has at least 4 different sets of per packet overhead (ATM versus PTM, BRAS versus BNG) so even for this one ISP there is not one solution to the issue. And with BRAS/BNG shaping as used by say DTAG the actual VDLS2 related overhead becomes irrelevant compared to the overhead setting of that applied policer. I believe trying to simplify this complexity will lead to false overhead recommendations. I would rather direct people to better documentation how to deduce the overhead by measurements and research…

I think we can make a couple of usefully simplifying assumptions:

1: The encapsulation overhead on the wire is the same in both directions.

2: The BRAS is irrelevant, because we need to set an ingress qdisc below the line rate anyway in order to exert control, and the BRAS doesn’t apply on upload.

Does that help at all?

 - Jonathan Morton

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