Am 25.09.2015 um 01:36 schrieb Ratliff, Stanley <sratliff@xxxxxxxxxxx>:
For any configuration variable, it is possible to screw it up.A DEFAULT_METRIC_TYPE is configured on each AODVv2 router so that any
AODVv2 messages generated which are associated with that metric type do
not
need to explicitly include an indication of that metric type. This means
that when a metric type is not included in a message, DEFAULT_METRIC_TYPE
is assumed. When sending information about routes with non-default metric
types, the MetricType data element MUST be included.
Ooh not sure about this. It's ok if all your routers use the same
configuration, but if you want to include others organisations routers who
could be using a different default, the unspoken metric type will be
different, which will >>cause great problems. I believe that we should
never assume a default type. However I'm open to some text that caveats the
use of the implied default stating that Here Be Dragons.
Nevertheless, people use configuration variables and this is a good example
of the value of doing so.
While I agree that "for any configuration variable, it is possible to screw
it up", I respectfully disagree with the follow-on statement "...people use
configuration variables, and this is a good example of the value of doing
so." Actually, IMHO, it's a great example of why you would *not* use
configuration variables. As John states, routers in an AODVv2 network *might*
use different defaults, and therefore, problems will ensue. But those
problems would *only* ensue precisely because a default was configured, and
therefore, not announced. The fix is to *always* explicitly include an
indication of metric type. That way, there's no possibility of being
misinterpreted. I believe that is a much better approach.
Regards,
Stan
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