I believe Cisco recommends

that you not have an OSPF area with more than 90-100 routers (Might have more routers nowadays) . Additionally

it is Cisco's recommendation that you not have more than 200 subnetworks per

an area. Again .. these are recommendations and the network topology can

have a dramatic effect on what are stable numbers for other networks.

Is there is Cisco article which provides more detail regarding this subject?

George, I see you've marked Stephen's post with a resolution flag, which is fine, but as Harold noted in his post, "it depends". There are even more considerations than what the Cisco reference document notes under "Number of Routers per Area". Some are a bit exotic, such as the IOS you're using and what internal OSPF enhancements it supports. Some depend on IOS configuration. Much depends on topology, link stability, etc.

OSPF geneally works well until some point that pushes it "over the edge". How many routers to have in an OSPF area is somewhat akin to how many hosts you can have within a subnet.

Recommendations for X number of routers per OSPF area, with typical OSPF best practice configurations, typically work just as about as well as X number of hosts per subnet. Both often are "safe" for typical situations, but both also might not be suitable for your network.

So, be careful using any one set of recommendations/considerations.

What is the maximum number of routers in an OSPF area which would be safe for most configurations?

Should a new OSPF area be defined when a WAN link is involved?

It might if your intent is to control volume of LSAs being passed across the WAN link using an ABR. Or, you want to protect other routers from the impact of link flapping, again filtering at ABRs.