[Bloat] configuration on an OpenVPN server

[Matt Taggart <matt@lackof.org>]

Hi,

I would like to configure SQM on an OpenVPN server and I am thinking 
about how to do this. I have already setup piece_of_cake on the upstream 
connection(in this case 900Mbit down/250Mbit up). I think that by itself 
should do a decent job of keeping things fair between all the VPN 
clients: they are assigned private IPs and triple-isolate should do the 
right thing.

But OpenVPN creates a tun device for that traffic and I could 
potentially do more to manage the VPN traffic separately from the server 
host traffic. One thing that occurred to me is that due to asymmetric 
upload/download the host has, and the fact that the VPN traffic has to 
go to/from the client, maybe the download rate of the tun device will 
never exceed the upload rate of the host (since we need to retransmit 
that data to the clients) and vice versa for the upload? So to force 
myself to be a bottleneck should I have qdiscs on the tun device 
limiting to ~240Mbit in each direction?

Hopefully that is clear. Let me know if it's not. Also anything else I 
should consider in this situation?

I don't have much control of the VPN client hosts, but I could recommend 
openvpn settings if there is anything that would help (can you turn on 
ecn there, etc?)

Thanks,

-- 
Matt Taggart
matt@lackof.org