[Cake] #17

Sebastian Moeller moeller0 at gmx.de
Tue Apr 14 03:03:21 EDT 2015

Hi Jonathan,

On Apr 14, 2015, at 02:58 , Jonathan Morton <chromatix99 at gmail.com> wrote:

>> On 13 Apr, 2015, at 23:10, Sebastian Moeller <moeller0 at gmx.de> wrote:
>> Does your method also work with the same encapsulations as skb_flow_dissect?
> I’m not sure.  Given the complexity, it’s probably neither a strict superset or subset; it’s also fairly likely that the outermost DSCP is returned from a tunnelled IP scenario.  ISTR that tunnels are supposed to copy the TOS byte on entry and the ECN field on exit, though there are almost certainly tunnel implementations which don’t do that.

	Fair enough, I was actually just thinking about PPPoE and VLAN/double VLAN tags, both of which change the offset of the TOS bits (as well as the offset difference for IPv4 and IPv6), so it seems a bit of a hassle handling down the encapsulation twice (once for the TOS bits and once for the flow hash). Most likely I am biased due to the computational cost of doing this with a naive set of tc filters ;) I guess.

Best Regards

> - Jonathan Morton

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