Is Level 1 only ISIS usable?

[YuriiIvanov92199]

Hi,

I've got simple network topology consists from 5-6 routers and in big future it can be up to 10 devices.

I think there is no need more than one area.

Can I use only Level-1 routing or this is antipattern and even in this simple scenario better use level1-2 topology.

[Georg Pauwen · Accepted solution]

Hello,

with a maximum of up to 10 routers, Level 1 only should be fine (unless of course you experience lots of instability, which will of course translate into a lot of IS-IS reconvergence).

Keep in mind that by default, all Cisco routers are L1-L2, so you need to change that default if you just want L1.