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

Phil Whineray phil at sanewall.org
Thu Jan 29 18:35:53 GMT 2015


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:

in the section: Overhead and MTU Calculations


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