The default route is used if either there are no other routes in the routing table or if none of the other routes apply to a destination. Including the gateway in the default route gives all traffic a next-hop address to use when leaving the local network. The gateway address is normally another router on the edge of the local network.

FortiGate units come with a default static route with an IPv4 address of 0.0.0.0, an administration distance of 10, and a gateway IPv4 address. Beginner administrators can use the default route settings until a more advanced configuration is warranted.

By default, all routes are displayed in the Routing Monitor list. To display the routes in the routing table, go to Router > Monitor > Routing Monitor.

Route leaking is the term used to describe the bi-directional flow of information between internal and external routing interfaces. By default, IS-IS leaks routing information from a Level 1 area into a Level 2 area. In order to leak Level 2 routing information into a Level 1 area, you must configure an export policy. Whether or not a route is leaked is determined by the ATT bit, using TLV 128 (for internal IP reachability) and TLV 130 (for external IP address information). For more information on TLVs, see “Troubleshooting IS-IS”.

To configure IS-IS route leaking, use the following CLI commands.

Enabling default-information-originate generates and advertises a default route into the FortiGate unit’s IS-IS-enabled networks. The generated route may be based on routes learned through a dynamic routing protocol, routes in the routing table, or both. IS-IS does not create the default route unless you use the always option.

Select Disable if you experience any issues or if you wish to advertise your own static routes into IS-IS updates.

The CLI commands associated with default information originate include: