Re: [Cerowrt-devel] some kernel updates

[Sebastian Moeller <moeller0@gmx.de>]

Hi Fred,


On Aug 23, 2013, at 15:02 , Fred Stratton <fredstratton@imap.cc> wrote:
[snipp]
>> 
>>> 
>>> Thus, in kernels >= 3.9, you would need to change/reduce your tc
>>> "overhead" parameter with -14 bytes (iif you accounted encapsulated
>>> Ethernet header before)
>> 
>> 	That is what I thought before, but my kernel spelunking made me reconsider and switch to not subtract the 14 bytes since as I understand it the kernel actively does not do it if stab is used.
>> 
>>> 
>>> The "overhead" of stab can be negative, so no problem here, in an "int"
>>> for stab.
>>> 
>>> 
>>>>> Meaning that
>>>>> some ATM encap overheads simply cannot be configured correctly (as you
>>>>> need to subtract the ethernet header).
>>>> 
>>>> 	Yes, I see, luckily PPPoA and IPoA seem quite rare, and setting the overhead to be larger than it actually is is relatively benign, as it will overestimate packe size.
> 
> 
> As a point of information, the entire UK uses PPPoA rather than PPPoE, and some hundreds of thousands of users IPoA.

	Lucky you! I guess one more reason to switch cerowrt over to stab, since PPPoA with VC/mux just adds 10 bytes of overhead, so if the ethernet would be accounted for already that would mean overhead -4 which HTB can not represent anyway. That said, unlike Jesper, I am not sure that tc stab includes the ethernet header by itself currently. Thanks for you input.

[snipp]
Best
	Sebastian