New OSPF Path Selection VS Traditional Path Selection, How it should be

[MHM Cisco World]

Wow Man that Prefect Work, 
thanks for sharing it

[Meddane]

Thanks MHM.

OSPF is described in many RFCs 1583 2328 3101 1587 etc..., and why it is important to read and understand these RFCs? because there are many differences about path selection and behaviors between them such as Type 7 translation, summary cost, forward address, and so on, this impact is very important to know it in order to interpret an OSPF behavior.

I published a dedicated book since 5 years about OSPF Demystified With RFC, through 101 scenario I explained the behavior per RFC's sections and I shown through different output and how to interpret these behaviors, also how a mismatch of RFC can create some dangerous problems of routing such suboptimal routing and routing loop.

[Joseph W. Doherty]

RFCs sometimes have "gray" areas or RFC revisions can have changes to prior behavior (although RFCs do try to avoid the latter).  (BTW, a good example of this is in QoS RFC using CS1 for less than Best Effort usage while the earlier IPPrec 1 and other AF1x classes are "better" than BE.)

These kinds of issues are also the type of things which will often trip you up when working in a mixed vendor environment or even when using all the same vendor equipment but there's a jump in software versions.