Routes can be redistributed into IPv6 IS-IS by performing the following configuration tasks:
The device can redistribute routes from the following route sources into IPv6 IS-IS:
The device can also can redistribute Level 1 IPv6 IS-IS routes into Level 2 IPv6 IS-IS routes, and Level 2 IPv6 IS-IS routes into Level 1 IPv6 IS-IS routes.
Route redistribution from other sources into IPv6 IS-IS is disabled by default. When you enable redistribution, the device redistributes routes only into Level 2 by default. You can specify Level 1 only, Level 2 only, or Level 1 and Level 2 when you enable redistribution.
The device automatically redistributes Level 1 routes into Level 2 routes. Thus, you do not need to enable this type of redistribution. You also can enable redistribution of Level 2 routes into Level 1 routes.
The device attempts to use the redistributed route‘s metric as the route‘s IPv6 IS-IS metric. For example, if an OSPFv3 route has an OSPF cost of 20, the device uses 20 as the route‘s IPv6 IS-IS metric. The device uses the redistributed route‘s metric as the IPv6 IS-IS metric unless the route does not a have a valid metric. In this case, the device assigns the default metric value to the route.
An IS-IS LSP can hold around 32,000 IPv4 routes or 11,000 IPv6 routes. This number can vary depending on the prefix length of the routes.