How do I advertise the default route to OSPF when there are 2 ISPs on the egress interface?

Hello everyone,

Today I will share with you how to advertise the default route to OSPF when there are 2 ISPs on the egress interface.

Issue Description

Customer feedback that there are 2 ISPs and when one is down, users will not go to another.

All of the devices that run OSPF and the default route are advertised to OSPF.

USG version: V500R001C30SPC100

NE version: NE05E V300R002C10SPC200

Handling Process

Remote to check the configuration.

Both NE advertises the default route as below:

OSPF 1

Default-route-advertise type 1

OSPF 1

Default-route-advertise type 1 cost 200

Check the route on NE1, there is no default route from OSPF from NE2.

Root Cause

If neither always nor permit-calculate-other is configured,

·when there are active default routes of other processes in the routing table of the host, the device does not calculate the default routes from other devices.

·when there are no active default routes of other processes in the routing table of the host, the device still calculates the default routes from other devices.

Solution

Modify the configuration on NE1 as below:

OSPF 1

Default-route-advertise permit-calculate-other type 1