OSPF Area

[Rishi.WWN]

I want to know in which area should the arrow mark interfaces 

[luis_cordova]

Hi @Rishi.WWN 

My recomendation:

Router0 Gig0/0 = area 0

Router1 Gig0/1 = area 0

All OSPF areas must have a network shared with area 0.
In your case, router 0 will be the ABR of area 1.

Regards

[Rishi.WWN]

Thanks for you kind reply. It's helpful.

[paul driver]

Hello
Depends on your overhall topology, but looking at what youve posted then there is no reason why it cannot be area 1 as it looks like that 1941 rtr has other interfaces in area 0

[Joseph W. Doherty]

Like Paul, much would depend on your overall topology and whether you're using "special" area and/or summary addressing. That link would function in either area zero or area one.

One common recommendation is for ABRs to be a bit more "powerful" than your other routers because they are computing SPT for multiple areas. Using that criteria, router 0 should be the ABR and if so link would be in area zero as Luis recommended.

[Giuseppe Larosa]

Hello,

both solutions are possible the ABR(0,1) role can be on R0 or R1 the area in which R0-R1 link belongs to depends from this design choice.

So I agree with all of the proposed solutions by @Joseph W. Doherty @paul driver and @luis_cordova 

The power of OSPF multi-area in internal route fine control by using area filter-list command this is my personal opinion it is not done for scalability anymore.

As much as 800 routers in same area have been reported by Russ White.

Minimiize external routes, use passive-interface instead of redistribute connected.

Use NSSA area instead of stub areas to allow for future redistributions if needed.

Use OSPF priority on LAN segments to avoid to have the same routers elected DR on multiple segments.

Hope to help

Giuseppe

[Rishi.WWN]

Thanks for your help.