• Describe what an IP VPN is and explain the difference between different VPN types.
• Recognise the design and implementation issues involved in implementing an IP VPN.
• Explain how the various technologies involved in an IP VPN work.
• Describe and implement
  • PPTP VPNs
  • L2TP VPNs
  • IPSec
• Evaluate VPN products.

VPN overview
What is a VPN? What is an IP VPN? VPNs vs. Private Data Networks, Internet VPNs, Intranet VPNs, Remote access VPNs, Site to site VPNs, VPN benefits and disadvantages.

VPN Tunnelling
VPN components, VPN tunnels, tunnel sources, tunnel end points, hardware based VPNs, Firewall based VPNs, software based VPNs, tunnelling topologies, tunnelling protocols, which tunnelling protocol should you use?, requirements of tunnels.

VPN security components
Critical VPN security requirements, Encryption and authentication, Diffie Hellman, DES, 3DES, RSA, PKI, Ca server types, pre shared keys versus certificates, Enrolling with a CA, RADIUS in VPNs.

PPP
Encapsulation, operation, authentication. Exercise: Setting up PPPoE and analysing PPP packets.

PPTP
Overview, Components, How it works, control and data connections, GRE. Exercise: Building a PPTP VPN.

L2TP
Overview, components, how it works, security, packet authentication, L2TP/IPSec, L2TP/PPP, Layer 2 versus layer 3 tunnelling. Exercise: Implementing a L2TP tunnel.

IPSec
AH, HMAC, ESP, transport and tunnel modes, Security Association, use of encryption and authentication algorithms, manual vs automated key exchange, NAT and other issues. Exercise: Implementing an IPSec VPN.

Intranet VPNs
Headers, architecture, label switching, LDP, MPLS VPNs.

VPN products and services
PE and CPE, management, various VPN products.

VPN issues and architectures
VPN architectures: terminate VPN before/on/after/in parallel with firewall, resilience issues, VRRP, performance issues, QoS and VPNs