What is the difference between a Policy-based VPN and a Route-based VPN?
| Knowledge Base ID: | KB4124 |
| Version: | 7.0 |
| Published: | 26 Aug 2009 |
| Updated: | 26 Aug 2009 |
| Categories: |
Firewall/IPSec_VPN IPSec ScreenOS |
The article briefly covers the differences between a Policy-Based VPN vs. a Route-Based VPN. In addition, it explains how to identify quickly which type is configured for an existing VPN.
Problem:
Which type VPN is configured, Route-Based or Policy-Based?
When should I configure Route-Based or Policy-Based?
Policy Based:
- A Policy Based VPN is a configuration in which a specific VPN tunnel is referenced in a policy whose action is set as Tunnel. The tunnel icon appears as either a Lock or as a Lock with directional arrows as shown in the sample below. The icon below indicates the policy is configured for a Bi-Directional Tunnel.
Common Reasons to use a Policy-based VPN:
- Remote VPN device is a non-Juniper device
- Need to access only one subnet or one network at the remote site, across the VPN
Route Based:
- A Route Based VPN is a configuration in which the policy does not reference a specific VPN tunnel. Instead, a VPN tunnel is indirectly referenced by a route that points to a specific tunnel interface. The tunnel interface may be bound to a VPN tunnel or to a tunnel zone.
- When a tunnel interface is in a security zone, a tunnel interface must be bound to a VPN tunnel. This is necessary in order to create a routing- based VPN configuration. The tunnel interface can be numbered or unnumbered. If it is unnumbered, the tunnel interface borrows the IP address from the security zone interface.
- A tunnel is a means for delivering traffic between points A and B, and a policy as a method for either permitting or denying the delivery of that traffic. Simply put, ScreenOS allows you the freedom to separate the regulation of traffic from the means of its delivery.
- If the tunnel interface does not need to support Policy Based NAT, and the configuration does not require the tunnel interface to be bound to a tunnel zone, the interface can be specified as unnumbered. An unnumbered tunnel interface must be bound to a security zone; it cannot be bound to a tunnel zone. An interface must also be bound to the security zone whose IP address the unnumbered tunnel interface borrows.
Common Reasons to use a Route-based VPN:In addition, the Route Based VPNs must include the following configuration information:
- Tunnel Interface
- Phase I VPN Gateway configuration (listed under VPNs > AutoKey Advanced > Gateway on the WebUI)
- Phase II VPN configuration (listed under VPNs > AutoKey IKE on the WebUI); including:
- Local and Remote Proxy ID
- VPN configuration bound to tunnel interface
- Route for remote network pointing to tunnel interface
- Policy specifying action of "Permit" to allow traffic
- Source or Destination NAT (NAT-Src, NAT-Dst) needs to occur as it traverses the VPN
- Overlapping Subnets/IP Addresses between the two LANs
- Hub-and-spoke VPN topology
- Design requires Primary and Backup VPN
- A Dynamic Routing Protocol (i.e. OSPF, RIP, BGP) is running across the VPN
- Need to access multiple subnets or networks at the remote site, across the VPN
Troubleshooting