PPTP , IPSEC/L2TP performance

PPTP , IPSEC/L2TP performance

Post by Roy Sande » Fri, 22 Aug 2003 18:41:46


I'm working on a project with VPN's.
I've succesfully set up a PPTP server and a IPSEC/L2TP server with
As this all seemed to work, i did a little performance test.
When i downloaded via the LAN it would go around 1,7 Mb/s with 1
When i tried with multiple clients from outside the LAN the
performance is somewhat crap. i can get about 300-400 kb/s out of the
box and that is about it.
both with IPSEC/L2TP and PPTP seem to have this problem.
The server that i used isn't that fast its only a PII 350Mhz.
The WAN connection to the internet is a 100 Mbit surfnet connection.
The clients i used to test from outside the LAN should be able to
download faster.
I tuned the MTU a bit but not really a difference. its about 1410 now.
My ifconfig says that the MTU of the pppX interface is 1406.

Q:Why is the performance from outside the LAN so much worse ?

Q:tcpdump tells me the kernel drops about 1/5 of the packets when
there is a lot of traffic comming tru.

Q: Could it be the machine that isn't capable of creating GRE packets
fast enough to multiple client ?

Q: is this a kernel restiction with /dev/pts ?

Any comments/advices are appreciated.

-- Roy Sanders


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