The 'less wrong' overhead figure is 12.  The incumbent telco BT who provide access to the 'last mile' (or the bit from the nearest FTTC cabinet and the property) use a VLAN tag, adding another 4 bytes to each frame going over the wire. 


The above guesswork based on SIN498 http://www.sinet.bt.com/sinet/SINs/  (and inspection of the default settings on a BT supplied modem)  I offer it as in theory being 'less wrong' rather than a practical 'correct'.


On 23/08/16 16:13, techicist@gmail.com wrote:
Hello,

Thank you for your quick reply.

I take it that one of the DHCPs should read PPPoE?

Yes, you are quite correct. It should read: "TalkTalk uses DHCP to obtain an IP address and not PPPoE as most other ISPs do." But I think you understood that :)

My sync speeds on VDSL2 have been very stable for the last 84+ days so my calculated figures will stay the same for some time, I would like to think. My DS sync speed is 58976Kbps and thus I have calculated a reference value of 58068Kbps based on your formula. The US sync speed is 10422Kbps and the reference value for this is 10261Kbps.

Setting the reference values to 50%, I have: 29034Kbps for the DS; and 5130Kbps for the US. I will test with these numbers shortly. Am I right to assume I can just paste these into the SQM interface on LuCI? I will set the "Queuing discipline" to cake and the "Queue setup script" to piece_of_cake.qos.

I assume also at this stage, to set "Which link layer to account for" as none (default)?

I will then increment the values I have pasted into LuCI (assuming that is correct) as you have said. At this point, with an assumed overhead of 8, do I just choose Ethernet with overhead... and then set the "Per Packet Overhead (byte)" to 8?

Is there any benefit of going through UCI?


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