Chapter 1 VPN Tunnel in English
Chapter 2 SITE to SITE VPN in ENGLISH
Chapter 3 Remote Access VPN in ENGLISH
VPN Tunnel Theory:
Understanding the concept of VPN is very IMPORTANT.
If VPN LOGIC is clear the it would be very easy to understand how we create a VIETUAL or a LOGICAL Tunnel.
We use INTERNET as a backbone N/W on which VPN is LOGICALLY created.
Since INTERNET can be used by any their are chances that our data can be CRACKED or LEAKED. Since we are SENDING & RECEIVING our PRIVATE DATA over PUBLIC INTERNET. So how is the DATA PROTECTED?
VPN are comming for our RESCUE.
We put our PRIVATE DATA inside the TUNNEL that ENCRYPTS the DATA if & only if IP SEC VPN is used.
IP SEC VPN only supports UNICAST Data Packet.
On N/W we have multiple DATA Traffic types.
VPN GRE Tunnel will ENCAPSULATE the different DATA Traffic Patterns & put inside the VPN GRE Tunnel.
The resultant VPN GRE Tunnel packet is a UNICAST Packet.
VPN GRE Tunnel do not provide SECURITY.
Combining IP SEC VPN Tunnel & VPN GRE Tunnel is IMPORTANT.
So VPN GRE Tunnel i.e. UNICAST Packet is put inside the IP Sec VPN Tunnel.