With regards to the items below, I would say that Cisco follows the RFC, 
but just describes the issues a little differently. See comments below.

At 04:28 PM 4/16/02, Kane, Christopher A. wrote:

>It's within the Hello protocol that there are certain criteria that must be
>met. ACCORDING TO CISCO they are: Hello/Dead Interval, Area ID, Stub Flag
>and Authentication [method and password]. So, I wanted to see what RFC 2328
>had to say about it. I also checked John T. Moy's book, Anatomy of an
>Internet Routing Protocol. In both of those sources I find that the
>following must match: Network mask, HelloInterval and RouterDeadInterval and
>the E-bit of the Options Field. The exception being the Network mask
>(depending on the Network Type in use).
>
>RFC states:
>HelloInterval

Cisco says this must agree also.

>RouterDeadInterval

Cisco says this must agree also.

>Network Mask

The RFC says to ignore this on point-to-point networks and on virtual 
links. Maybe Cisco just doesn't mention it because it's not a rule that 
always applies.

>E-bit of Options Field (Area capable of processing AS-external-LSAs)

That's what Cisco calls the stub flag I bet.


>Cisco implementation:
>Hello/Dead Interval
>Area ID

The RFC covers this too, but in the general discussion, not just in the 
discussion of Hellos. The Area ID in an OSPF packet must match the area of 
the receiving interface (except in the case of virtual links, in which case 
it must indicate the backbone).

>Stub Flag
>Authentication Method/password

The RFC says this must agree on every OSPF packet. It just doesn't 
specifically mention that it must agree on Hello packets.


>I realize vendors have the choice of how closely they follow an RFC.

If the RFC says "must" then a vendor must do what it says. It's only when 
it says "should" or in grey areas where the authors didn't make something 
clear that you run into problems.

>  I'm
>just trying to make sure I understand the protocol for what it is and for
>how Cisco deploys it. Can someone experienced with this protocol check my
>understanding?
>
>-chris
________________________

Priscilla Oppenheimer
http://www.priscilla.com




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