[Firehol-support] QOS overhead calculations, PPPoE on leased line

[Tsaousis, Costa]

Strange setup.
Most Ethernet providers I have worked with used just MPLS to provide a
virtual private cloud, over their physical cloud.

Anyway, overhead 22 seems right to me if they just run PPPoE.
If they also use VLANs or MPLS behind the scenes the overheads may be higher.

Check this calculator http://baturin.org/tools/encapcalc/

Costa

On Thu, Jan 29, 2015 at 8:35 PM, Phil Whineray <phil at sanewall.org> wrote:
> Hi
>
> I got the following statement about a leased line:
>
>> The maximum MTU is 1500 bytes, we do not support Jumbo Framing.
>>
>> As the service is Ethernet we only use PPPoE, there is no ATM
>> encapsulation.
>
> Can anyone confirm the following calculation is correct?
>
>  2 bytes = PPP
>  6 bytes = PPPoE
> 14 bytes = Ethernet
> ---------------
> 22 bytes = total overhead
>
> So for FireQOS:
>
> LINKTYPE="ethernet overhead 22 mtu 1500"
>
> I've based it on info I found here:
>   http://ace-host.stuart.id.au/russell/files/tc/tc-atm/
>
> in the section: Overhead and MTU Calculations
>
> Cheers
> Phil
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