On Thu, 20 Jan 2005, Jordi Meya wrote:
I want to use OpenVPN for a Lab, and I'd like to know which is the overhead
that the SSL-VPN layer represents (I want to analyse the impact on the
network performance when using VPN's). I have been scrolling though the
RFC2246 and "googleing" but I can't find this information. Could any of you
point me to a good resource?
Google this list archive :-)
In this post James wrote:
It varies depending on options. With a TUN-style tunnel over UDP using
the default TLS options, the per-packet overhead is:
41 bytes security layer overhead (includes packet tag (1), HMAC-SHA1
signature (20), initialization vector (16), sequence number (4))
28 bytes tunneling overhead (includes IP + UDP header)
Total: 69 bytes per packet
If your data stream is compressible, you can potentially gain back all
of this overhead.
If you're interested in the details of the protocol, have a look at the
comments in ssl.h in the openvpn source.
Mathias Sundman (^) ASCII Ribbon Campaign
OpenVPN GUI for Windows X NO HTML/RTF in e-mail
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