Dummynet Issue

Submitted by Anonymous
on July 7, 2009 - 12:01pm

Hi,

I'm having intermittent issues with my implementation of Dummynet.

I've got two FreeBSD 7.0 systems running an IPSec/Racoon VPN which runs stably. On one BSD box, I've set up a dummynet pipe to limit the amount of traffic going across my gif tunnel.

eg.
ipfw pipe 1 config bw 300Kbit/s queue 80Kbytes
ipfw add pipe 1 all from any to any via gif0

Here's my problem: everything works fine going across this tunnel except for Samba file-sharing.

Windows PC-to-Windows PC SMB file sharing works fine
Linux-to-Linux Samba file sharing works fine

** Frequently Windows to Linux (and vice-versa) times-out when trying to initiate a file transfer. If I remove the pipe entry and allow traffic to freely move across the gif tunnel, the transfer works successfully. I then put the pipe rules back in and new transfers continue to work.

After a while (usually when communication between the Windows & Linux PC's has been idle for a bit), the problem occurs again. Transfers time out, I remove the dummynet rules, start the transfer, re-enable dummynet and it continues to work for a while.

-- The problem ONLY happens between Windows & Linux PC's platforms.

-- I've tried increasing the pipe size & queues to ridiculous amounts (eg. 10Mbit/s), doesn't cause the transfer to work - only disabling dummynet does

Any ideas?

Thanks,
Brad

network monitor

on
July 8, 2009 - 3:34pm

you could use something like tcpdump or wireshark to find out which request times out. which tcp options (cf. /proc/sys/net/ipv4/ under linux) are set on the machines?

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