Tiernan's Comms Closet

Geek, Programmer, Photographer…

2 Cable modems = Double speed? Part 3

[NOTE] This part 3 in a series of posts. The rest can be found here.

In Part 1 of this series I explained the why and what I wanted to do for this “project”. In Part 2 I did some basic testing of both MPTCP and MLVPN. I also mentioned trying MMPPP using vtund but it has been a while since I did that testing, and it had not been on bare metal. So, this post is a follow up, where I am using bare metal.

So, first, the setup:

  • ProLiant box is running Debian 8.3 x64, and has both vtund and ppp installed
  • Digtial Ocean box also has Debian 8.3, vtund and ppp installed
  • walked though the guide from John Lewis and made some changes to the configs. the main ones are mentioned below

Once done, i installed both iperf and iftop on both boxes, and ran

iperf -s

on the Digital Ocean box and

iperf -c -d

on the local box. And, well, the results where not as expected. Pretty poor actually:

First, using Squid installed on the DO box, i tried using WGET to download a file using it. If I did this on the DO box itself, i was getting 100MBytes/s… When I ran it over the MLPPP box, well, under 7 was achieved.

Then i though it might have been Squid. So, since the file had been downloaded to DO, i SFTPed into the box over the MLPPP link, and tried again… Again, pretty poor result. I think i seen it hit about 7MB a sec at one stage.

Here is what is showing on the DO box when running the SFTP download. You can see 2 connections from the 2 WAN links at home hitting the box, and they are balanced. Its just nowhere near the speed they are capable of.

I did not get a screen shot of this, but when I tried with iperf, thinking it might have been overhead of SFTP or Squid, I was getting results matching what I was seeing with SFTP. Downloads in the 55-60mbit/s range for download and 40ish for upload. 40 is still faster than 1 link, mind you…

I mentioned that I had made some minor tweaks to the configs from what John had written. Well, mostly it was config changes to how routing was done. In Johns case, he is bonding a DSL and a HSDPA connection, so he had setup to do for logging into his PPP modem and connecting. Also, when he setup the interfaces, he routing tables in there. I have mine setup in a single config file, like as follows:

I have changed the names from adsl1 and 2 to WAN1 and 2, and the IPs are changed from internal IPs to my public IPs. I manually run this when setting up my connection.

Nothing else on his config files have changed. I did not do any of the masquerading stuff, mainly cause this was testing. I just want a tunnel to start with. When reading the vtund.conf file, you can see that encryption and compression are both turned off, and and the same in the ppp configuration. I also don’t think the issue is to do with the CPU performance, since these are the screenshots of top running on both boxes:

in both cases, CPU usage is sub 6% for VTUN and SSH seems to be using less than 10%. So, now, I’m baffled as to why this is not performing as expected… More testing required!

[update 4/4/2016] - fixing images so they are clickable…

“2 Cable modems = Double speed? Part 3” was last updated: July 13, 2018: fixing aliases (c8b9f0d). Found an issue? Improve this page