On Fri, Dec 14, 2001 at 11:27:09AM -0500, Howard C. Berkowitz wrote:
>
>
> While I always hesitate to cite something ISO-ish, there is
> terminology in the ISO 9646 conformance testing methodology that
> might serve as a _starting_ point for explicit formulation.
>
> 9646 defines three kinds of test cases:
> 1. Correct, where the PDU is completely appropriate but may test boundary
> conditions within the specification,
> 2. Incorrect, where there are syntactical errors, possibly of a type that
> a PDU can be partially decoded,
> 3. Inopportune, which could be better defined. In general, it appears to
> refer to the behavior caused by the reception of a PDU not relevant to
> the current state of the receiver (e.g., a BGP speaker receiving an
> UPDATE before the peering is established).
>
> Depending on how one defines "state," I think the inopportune case is
> a starting point for what is being called semantic correctness. Other
> things that might fall under semantic incorrectness include:
>
> 1. Reception of information dependent on a negotiable capability that
> was refused during capability establishment
> 2. Martian/bogon addressing and the like
>
> This taxonomy really doesn't have a place for such things as sanity
> checking (e.g., BGP prefix limit) or DoS detection. But it's a start.
>
I don't think this addresses the issue of semantic correctness at all.
The example being hinted at by some, I suspect, is confederation components
in a syntactically correct AS_PATH causing a peer to reset simple because
the peer didn't understand those components. In other words, good syntax
with bad semantics caused a network failure, and that is something to be
avoided, if possible.
Ben
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