Multilink PPP Download Speeds With Round-Robin Packets

[Michael MacLeod]

Hello all,

I've got two DSL lines running to my house, and two WAN NIC's
installed in my FreeBSD router. I've been trying to get multilink ppp
working through my ISP (TekSavvy in Canada) for the last little while,
with mixed results. Each of my DSL lines sync's at 6016 kbits down and
800 kbits up. I have traffic working through the bonded connection,
and the upload speed is 1350 kb, which is about right for a 1.6
megabit connection minus network overhead. The problem I'm running
into is the download speed is only that of one of my downlinks (approx
5000kb, which is about right for 6 megabits minus network overhead).

TekSavvy enabled packet splitting on the upload side of my connection,
but are being cautious and only doing round-robin packets for the
download side. I assume they are worried about collateral damage to
non-multilink ppp users. I've posted to the dslreports teksavvy forum
about my problem, and another FreeBSD user posted parts of his config
and some speedtests that show that he has his download running at the
full bonded speed. I've also received still another ppp.conf file from
another FreeBSD user from the dslreports forums who was also able to
get full bonded download speeds. This leads me to believe that there's
something specific to my setup that is causing the problem.

In discussions on the dslreports forums I've compared my sysctl output
for net.inet.tcp with someone successfully getting full download
speed, so it doesn't seem to be there, though it could certainly be
elsewhere in sysctl. I'm already using ppp.conf files from someone
who's successfully made their download go full speed. It could be a
kernel option, but the other two users haven't reported changing
anything special in the kernel. Unfortunately, I'm relatively new to
FreeBSD, so I'm not sure where else to look.

I've documented large parts of the setup, and my problems, on a wiki page here:
http://bsdtips.utcorp.net/mediawiki/index.php/Mersault/MultiLink_PPP

And here are the important threads from the dslreports forums:
http://www.dslreports.com/forum/r19513042-MultiLink-PPP-Performance
http://www.dslreports.com/forum/r19719787-Still-Having-Multilink-PPP-Problems

If anyone has any ideas of where to look next, I'd be very grateful.

Mike