I'm investigating deep packet inspection and I'm wondering how DPI works in the context of VPN.
I don't know much about VPN, but I believe it functions as a "pipe within a pipe" so I'm basically viewing it as encrypted traffic flowing over my main ISP connection. Is this basically correct?
In other words, is VPN traffic fundamentally different from encrypted, I guess I'll call it normal, traffic as far as DPI is concerned? My understanding is that DPI can't inspect encrypted traffic throughly but it can notice patterns in the traffic and categorize into classes of traffic, such as peer to peer.
Is DPI able to do similar categorizations with VPN traffic by observing traffic patterns?