[Openswan Users] OpenSWAN transfer slowing down

Piotr Dzionek piotr.dzionek at intercon.pl
Tue Feb 19 07:01:28 EST 2013

I tried different MTU sizes at the begining but it did not help. However
I changed netstack to klips and now I have steady 35-40 MB/s. So my
problem is solved.

W dniu 18.02.2013 07:47, Muenz, Michael pisze:
> Am 15.02.2013 16:01, schrieb Piotr Dzionek:
>> Hi,
>> I have a problem with slowing down transfers over IPsec tunnel. I
>> have two servers with Debian 6 and Openswan 2.6.28+dfsg-5+squeeze1.
>> Normal transfer speed is sth between 50-70MB/s between them. However
>> when i use IPsec tunnel it starts with something like 20MB/s and
>> slows down to sth like 1-1.5MB/s just after a minute or two. Moreover
>> server load goes really up(not max). I have two quite powerful xeon
>> servers with aes-ni support and aesni_intel modules loaded. My config
>> is:
>> ...
>> What could cause this kind of problem? or maybe this should work that
>> way ? Normal scp transfer works very good so i dont really know what
>> is wrong.
> You should check MTU size, fragmentation and play with MSS values.
> Michael

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