multiple OSPF areas on ABR best practice

[Buddy_Olli]

Hi,

let's assume customer has an hub and spoke topology where the hub is the ABR and arouns 120 spoke location are connected to it. The hub is connected per area0 to the Datacenter switches. 

Customer asked if it is possible that each spoke location will be put into one area. So that there are 121 areas (120 spoke area + area0). 
See picture:

Is this a valid design ? Is that recommended or are there any considerations or drawbacks ? 
Alternatively we could put all the spokes into one area (i.e.100), so that we only have 2 areas. 

What would be the better design and why ? How about CPU and memory consumptions for both design. What is the better solution ?

Many thanks and Kind Regards,
BuddyOlli

[Joseph W. Doherty]

"Regarding the number of routers in a single area the limit of 50 is an old guideline and some providers have 300 routers in area 0 with no issues."

Indeed!  I was considering adding a reply noting I recall in excess of 200 routers in an OSPF area have been mentioned on these forums.  Possibly much to do Cisco's OSPF implementation and/or actual topology.

[liviu.gheorghe]

Another design best practice states that each area, including the backbone, should contain no more than 50 routers.