Default Rule
Default Rule provides a semiautomatic way to establish symmetric routing rules, while Routing Rule is a fullymanual way. Default Rule is a simple and efficient way to configure symmetric routing rules for tunnel transmission between FortiWANs. Although Default Rule is a simplified way to set routing rules up, it still contains the three basic elements that we introduced above. Default Rule filters traffic by Source and Destination while ignoring the Service (Service = Any). To set the default rules up, only the source IP addresses need to be specified on both FortiWAN units that a tunnel group connects. Then the symmetric FortiWAN units automatically negotiate for the destinations; One’s source in a default rule will become to the destination in the default rule on the opposite unit. In other words, Default Rule is the fully-connected association established by specified sources on local and remote units.
A Default Rule is attached to a Tunnel Group. The configurations of a tunnel group contains items for its default rules, so that traffic filtered out by the default rule would be transferred via this tunnel group, which is the second element for a tunnel routing rule we introduced above.Every default rule contains fail-over policy for transmission when the tunnel group fails; this is the third element for a tunnel routing rule.
| Add | Click the Add button to add a new rule. |
| E | Check to enable the rule. |
| Source | The source of the connection (See “Using the web UI”).
IPv4 Address, IPv4 Range and IPv4 Subnet: Specify the IPv4 Address, IPv4 Range or IPv4 Subnet that the traffic comes from to be filtered by this rule. LAN: To filter out the traffic that comes from LAN area. DMZ: To filter out the traffic that comes from DMZ area. |
| Fail-Over | Select a policy from the list. Once the tunnel group get failed (every single tunnel in the tunnel group fails), traffic will be diverted based on Fail-Over policies.
NO-ACTION: Traffic will not be diverted when the tunnel group get failed, and transmission will get failed. Auto Routing: Traffic will be re-evaluated against Auto Routing’s rules and transferred according to the Auto Routing policies. Transmission gets failed if there is no rule matches. Tunnel: [Group Name]: All the defined tunnel groups are listed for options. Traffic will be diverted to the specified tunnel group here, however, the diverted traffic will not be diverted again if the beck-up tunnel group is also failed. Note that it takes the same action as “NO-ACTION” if a tunnel group that is the same as what this default rule attached to is selected as back-up for fail-over here. |
Considering the illustration above, a tunnel group (Tunnel Group AB) containing two tunnels (Tunnel 1 and Tunnel 2) connects two FortiWAN units (FWN-A and FWN-B) that two internal networks connect respectively to. Configurations of default rules on two sites are as follow:
Default rules sat on FWN-A
| Source | Fail-Over |
| 192.168.1.10 | NO-ACTION |
| 192.168.1.11 | Auto Routing |
| 192.168.1.12 | Tunnel: BackupGroup |
Default rules sat on FWN-B
| Source | Fail-Over |
| 192.168.2.10 | Tunnel: BackupGroup |
| 192.168.2.11 | NO-ACTION |
| 192.168.2.12 | Auto Routing |
The sources sat on FWN-B’s default rules, which are treated as destinations for FWN-A, are sent to FWN-A via the automatic negotiation. FWN-A then generates logically the following routing rules in system back-end.
| Source | Destination | Service | Group | Fail-Over |
| 192.168.1.10 | 192.168.2.10 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.1.10 | 192.168.2.11 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.1.10 | 192.168.2.12 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.1.11 | 192.168.2.10 | Any | Tunnel Group AB | Auto Routing |
| 192.168.1.11 | 192.168.2.11 | Any | Tunnel Group AB | Auto Routing |
| 192.168.1.11 | 192.168.2.12 | Any | Tunnel Group AB | Auto Routing |
| 192.168.1.12 | 192.168.2.10 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
| 192.168.1.12 | 192.168.2.11 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
| 192.168.1.12 | 192.168.2.12 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
The sources sat on FWN-A’s default rules, which are treated as destinations for FWN-B, are sent to FWN-B via the automatic negotiation. FWN-B then generates logically the following routing rules in system back-end.
| Source | Destination | Service | Group | Fail-Over |
| 192.168.2.10 | 192.168.1.10 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
| 192.168.2.10 | 192.168.1.11 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
| 192.168.2.10 | 192.168.1.12 | Any | Tunnel Group AB | Tunnel:
BackupGroup |
| 192.168.2.11 | 192.168.1.10 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.2.11 | 192.168.1.11 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.2.11 | 192.168.1.12 | Any | Tunnel Group AB | NO-ACTION |
| 192.168.2.12 | 192.168.1.10 | Any | Tunnel Group AB | Auto Routing |
| 192.168.2.12 | 192.168.1.11 | Any | Tunnel Group AB | Auto Routing |
| 192.168.2.12 | 192.168.1.12 | Any | Tunnel Group AB | Auto Routing |
In the example above, Source of every default rule is specified with single IPv4 address. It is a easier way that set up default rules by specifying Source with a IPv4 range, IPv4 subnet, LAN or DMZ.
Default Rule gives a great help to establish fully-connected routing rules while constructing an Intranet on many branch sites via Tunnel Routing. Consider an Intranet deployment over three branch sites, only three default rules (each one on a branch site) are required to establish the fully connection over the three sites, which requires six routing rules without using Default Rule.
Default Rule refers the configurations of LAN and DMZ in Network Setting to negotiate the routing rules if the Source is specified as LAN or DMZ for a default rule. It is necessary to re-apply the configurations of Default Rule to trigger the negotiation and update the default rules if any change to LAN or DMZ networks setting.