Hi there,

My network is growing... and i made decision about split it - from single to multiple areas OSPF.
So i have question about connecting routers which are (currently) connected by backup links and will be in different areas.
Can i redistribute eg. from area 1 to area 2 without area 0 ?

I thought about multi-instance ospf... in cisco i can do that.
What about MT ?

Thanks for any advices.

Regards

If you have more than one OSPF area all areas must connect to the backbone area. That's an OSPF requirement. There is no need to redistribute anything. ABRs (area border routers, routers that have interfaces in the backbone area and one or more other areas) take type - and 2 intra-area LSAs and flood them into other areas as type 3 LSAs, so inter-area routes just work (though it would be best to summarize area IP space on ABRs).

Whenever you can get away without redistribution don't redistribute. It can introduce routing loops and suboptimal routing. I would highly recommend against using different OSPF instances unless you have to, such as merging two already existent networks.

psm, you can use tunnels to brind nonbackbone areas to area 0.
Another variant is to use virtual-links, but it was broken since 3.30, so currently this is not good solution.