Overlay VPN – Old method;
- Easy to implement and well-known.
- Service provide just provides the L1/L2 connectivty between customer sites.
- Service provider will not participate in customer routing and hence customer need not to relay on SP.
- Optimal routing requires full mesh connectivity between customer sites. Need n(n-1)/2 virtual circuits for full mesh connection of “n” sites.
- Virtual-circuit has to be laid manually
- Encapsulation (GRE/IPsec) needs to be implemented in SP network. Ovehead.
Peer-Peer VPNs; – Currently deployed and efficient way with MPLS
- Optimal routing between customer sites is guaranteed.
- Routing information is exchanged between CE and PE routers.
- Configuration part is easier than in overlay model.
- PE router has to carry many customers’ routes. Bit overload on PE routers. (Not a big deal with current router design)
- SP network become responsible for customer network convergence. Any n/w breakage in SP might affect customer routing. Customer has to relay on Service Provider (SP). (Not an issue, with MPLS FRR)