Configuring IS-IS to Advertise a Default Route
Context
If IS-IS is configured to advertise a default route on
a border device that has external routes, the device advertises a
default route ::/0 in the IS-IS routing domain. All traffic destined
for other routing domains is first forwarded to the border device.
Configuring a static default route can also allow all the traffic to be first forwarded to a border device, which then forwards the traffic outside an IS-IS routing domain. However, this method leads to heavy workload in configuration and management when a large number of devices are deployed on the network.
In addition, advertising default routes using IS-IS is flexible. If multiple border devices are deployed, a routing policy can be configured to allow only the border device that meets the specified conditions to advertise a default route, preventing routing blackholes.
Procedure
- Run system-view
The system view is displayed.
- Run isis [ process-id ]
The IS-IS view is displayed.
- Run ipv6 default-route-advertise [ always | match default | route-policy route-policy-name ] [ cost cost | tag tag | [ level-1 | level-1-2 | level-2 ] ] * [ avoid-learning ]
IS-IS is configured to advertise a default IPv6 route.
By default, IS-IS does not advertise a default route.