How many routers an OSPF or IS-IS area can have

[David Wang]

Hi,

I have a question about the size of the IS-IS and OSPF area. What is the
guidelines in setting up the IS-IS or OSPF area? How many routers an area
can have? What are the key facts to determine how many routers an area can
have? router memory size? router interface bandwidth? or some other facts?
Is there any quantitative relationship among various parameters?

Thank you for your help!

David