7.1. Area Scalability
A logical question to ask when first learning OSPF or IS-IS is “What is the maximum number of routers I can put within a single area?” You will find no shortage of engineers answering with their own “rule of thumb.” But the more people you ask, the wider variation of opinions you will encounter, typically stating somewhere between 10 and 100 routers as a maximum. About the only thing these rules of thumb have in common is that they are wrong.
The maximum number of routers you can put into an area depends on a number of variables, and so is itself a variable. One of these variables is the number of links in the area. Each link is represented by a subnet address, which must be recorded in the link state database. If the link ...
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