VLAN security hackable?

["Raj Shaz" <rajshas () gmail com>]

I want to know how the VPNs created on cisco routers encapsulate the
data. Need to know the basic intricacies like
which algorithm is used?
how does packet transform.
Is it a IOS capability or there is some VLSI chip inside the box which does it.
Can it be hacked? theoritical/pratical? how?
VPNs on cisco-cisco network are same as cisco-anyother network ?
what is throughput with and without VPN on similar data-circuits.

Googling dint helped. So im here. requested link any for detailed study

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