[Openswan Users] OpenSWAN transfer slowing down

Muenz, Michael m.muenz at spam-fetish.org
Mon Feb 18 01:47:21 EST 2013

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.


- Cisco, Linux, Networks

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