Cake and WAN packet overhead (VDSL2 PPPoE PTM UK)

  • SNBForums Code of Conduct

    SNBForums is a community for everyone, no matter what their level of experience.

    Please be tolerant and patient of others, especially newcomers. We are all here to share and learn!

    The rules are simple: Be patient, be nice, be helpful or be gone!


Occasional Visitor
Hello everyone

I'm trying to figure out what the ideal wan packet overhead number for a VDSL2 PPPoE PTM (with vlan tagging) connection would be. It's very popular in the UK for FTTC by ISP such as BT (which I have).

Cake seems good enough right now (A+ in bufferbloat) but I would still like to understand the proper values. When you select VDSL2 PPPoE PTM from the drop down, you get these numbers:
Now after looking at this:

It seems like 30 would be correct. However, since my ISP has vlan tagging I need to look at ether-vlan and add 4 so in total 34. I was still not sure on the "mode" section. In the drop down box it has 3 options: Normal, ATM, PTM

It's likely that Normal = noatm. ATM and PTM are the compensations applied to bandwidth. I did think if I should even use the PTM flag because of this post: viewtopic.php?p=885000#p885628

It should just be better to do the 64/65 calculation (0.984) on bandwidth. Apparently this isn't as CPU intensive or something?

So my questions are:

1: Should I actually be setting 34 on wan packet overhead based on my connection?
2: Should I set the PTM flag or take care of it myself in bandwidth number (0.984)?

Thank you

Similar threads

Latest threads

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!