Set two different area-ID on the same ISIS process

[AndreaT1197]

How I can set two area-ID under the same ISIS process? Is this possible and would not affect the exisiting area-id? Or should I create a new ISIS process to set the new area-ID?

[balaji.bandi]

What is the user case here for ISIS required for 2 Router ID ?

yes if you have different ISIS process - that will be different process so you can and need to have different rouer-id.

[Giuseppe Larosa]

Hello Andrea,

it is possible to set up to three different area-id in a single ISIS process.

However, the usage should be limited in time and is intended to be used for migration purposes ( for example to migrate all routers in two areas in a new unique area).

If you want to have your router to run two different instances of IS-IS of course they will need to be in different areas -> use two different NET and in this case configuration can be permanent you will add a tag identifier to each IS-IS instance when configuring them so that you can decide which IS-IS instance is associated to a specific interface.

Example:

instead of simply using ip router isis you will use ip router isis F1 where F1 is the name of the IS-IS instance.

Hope to help

Giuseppe