Raspberry Pi client Throughput

nexzus

TL;DR: How much OpenVPN tap throughput can I expect using a Raspberry Pi as an Internet gateway/VPN Tunnel Router?

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Currently using a 5 year old Linksys 160N (384 MHz BroadCom CPU, 4MB Flash ROM, 32 MB RAM) as my Internet/VPN Tunnel Router. It has DD-WRT with an (stripped down?) OpenVPN client on it.

Setup works fine. I can connect with a tap tunnel to a VPN provider's OpenVPN server a 13-ms ping away, about 120 km geographically. (Vancouver, BC to Seattle, WA). Using IP tables, I route traffic from only my PS3s over the tap tunnel. Everything works fine - I can watch US netflix, Hulu Plus and my un-blacked-out Canucks on GameCenter (eventually, when Sony gets it act together), and everything else goes out through my ISP gateway. 1

My concern now is speed. Using the PS3's network test, I get about 4.1 mbps down and 1.5 up. My connection is 25/2, and I can get about 18 from a speedtest server in seattle. I need at least 5 for Best Netflix, and 8 for their new "Super HD" service (assuming my VPN providers' ISP will join)

Which points to my poor little router there, showing during a "Medium/HD" Netflix stream a consistent > 1.5 load factor from UpTime, and > 90% CPU utilization from Top. It just can't handle anything more, and I can't disable encryption or compression, else the connection doesn't work. fast-io is enabled, and logging is Verb 0.

So I turn to the Raspberry, with its 700 MHz, overclockable ARM CPU, and 512 MB or RAM, as a possible low-power, low cost alternative. Wondering if the users that know this OpenVPN software can give me a guesstimate as to how well this setup will perform. Thank you.

For clarity, here's my conf:

remote ip.address 1194 udp 
client 
dev tap 
resolv-retry infinite 
nobind 
persist-key 
persist-tun 
mute-replay-warnings 
ca /tmp/ibvpn/ibvpn.com.crt 
log-append /tmp/ibvpn/vpn.log 
comp-lzo 
verb 0
fast-io 
mute 20 
ns-cert-type server 
fragment 1300 
route-method exe 
route-delay 2 
auth-user-pass /tmp/ibvpn/user.conf 
reneg-sec 0 
script-security 3 system 
up /tmp/ibvpn/change_resolv_conf.sh up 
down /tmp/ibvpn/change_resolv_conf.sh down

1. Yes, I know services such as (rhymes with sunblock fuss) can do this functionality, but I like to do things the hard and geeky and arguably correct way.

skylla

Maybe a bit of an old thread, but google got me here...

I have not tested openvpn on my raspberry pi yet, so I do not have anything more than guesses, but with a simple ssh-tunnel i get around 8 mbit/s throughput with my RPi (standard settings/encryption).

Additionally I am guessing the router you have now is a similar architecture (do not know the exact differences between armv5/v6/v7) and roughly half the clockspeed of the RPi, and since it is userspace applications on a not entirely different stack a guess could be that performance differences would be similar.

On the other hand I get around 8-10 mbit/s throughput with an openVPN server running on my netgear WNR3500Lv2 (480 MHz, running tomato) and default settings, when disabling encryption and packet authentication it increases to around 14 mbit/s and when also adding similar verbosity and fragment settings as you I get around 18 mbit/s througput.

All in all I would probably expect around 8 mbit/s, and maybe more with some tweaking, but I wouldn't hope to max a 25mbit/s connection, but my guesses may be very off...

nexzus

For anyone else coming in from google: the above poster was pretty much spot on. I'm able to get a Windows IE speedtest at just under 8 mbps and a PS3 speed test at just over 8 mbps.

I was able to stream 1080p netflix with no hiccups. Vnstat showed me hitting 8.5 mbps with top showing about 80% CPU (non-overclocked).

I was streaming NHL Gamecentre at 6-7 mpbs at 60-65% CPU.

I'm happy with the results.