A VPN that travels through a non-MPLS network requires a GRE tunnel. This tunnel can be either a static tunnel or a dynamic tunnel. A static tunnel is configured manually between two PE routers. A dynamic tunnel is configured using Border Gateway Protocol (BGP) route resolution.
When a router receives a VPN route that resolves over a BGP next hop that does not have an MPLS path, a GRE tunnel can be created dynamically, allowing the VPN traffic to be forwarded to that route. Only GRE IPv4 tunnels are supported.
To configure a dynamic tunnel between two PE routers, include the dynamic-tunnels statement:
- dynamic-tunnels tunnel-name {
- destination-networks prefix;
- source-address address;
- tunnel-type type-of-tunnel;
- }
You can configure this statement at the following hierarchy levels:
For more information about configuring routing options or BGP, see the JUNOS Routing Protocols Configuration Guide. For more information about VPNs, see the JUNOS VPNs Configuration Guide.