which is the format of a package created by openvpn?

[cergius]

I am doing a project to run trixbox through openvpn to connect to voip two
branches of a company, the matter is I'm doing the calculation of bandwidth for VOIP and I need to
know what is the format and the size of a pack formed by openvpn, I want something like
I put in this image here, the image is the overhead that occurs in ethernet but I wanna know the overhead would cause in a package created by openvpn, I searched a lot this information and I couldn't find it



thankyou, I hope your answers

[arnotixe]

You should download Wireshark (http://www.wireshark.org/) to have a look at your packages as they are transmitted.

NOTE that if you encrypt the traffic before traffic shaping, you will get bad results. You should prioritize (QoS) before any encryption is done.

The traffic shaping is unneccesary when there is zero network traffic, but when people start to load the network you really should have a prioritizer to give your VoIP traffic (RTP traffic, really) maximum priority. Which is impossible to do after the data is encrypted, case you don't know what data is flowing.

[kaneda]

Lot of us have similar problem beacuse the passtos parameter dont work on windows machines, if packet id being priorized from the source, when it becomes encapsulated as SSL packet it will preserve its priority bit and should be processed fist by routers on the ISPs cloud, in case of congested network.
(depending on ISPs)

At Spain we have problems with Vodafone beacuse in spite of they have a data plan with voip included, its appears to work nice only on mornings, at late evening network become congested and its very difficult to have good voip quality, Im going to try priorizing with gpedit.msc windows console forcing to give higer priority to packets with ip and dest port of openvpn tunnel, will give feedback here of results.

Kaneda