[Interop-dev] Network Topology JSON [was: OLSRd2 JSON APIs]

[Henning Rogge]

On Thu, Nov 20, 2014 at 1:02 PM, Nemesis <(spam-protected)> wrote:
> I got some feedback from Antonio Quartulli (batman-adv) to see how that
> would fit for batman-adv.
>
> He told me that "source" doesn't apply for batman-adv and should be omitted
> if "type" is "batman-adv".

It would be omitted in ALL currently existing protocols... but
source-specific routing will play an important role in multi-gateway
IPv6 scenarios in the future, so we should have the field there.

> We also reasoned about "cost" and "cost_type". The word "cost" implies that
> is better to have a lower cost, while some algorithms might do it
> differently.
> So peraphs using "metric" and "metric_name" would be more generic.

I think that is a really bad choice... we need a well-defined order on
the cost-field, otherwise external software cannot interpret this
reasonable. What use is the cost-value if you don't know which one is
better?

So I see two ways to allow metrics to go the other way around...

first would be to add a boolean field that tells you if higher is good
or bad. It makes comparing two cost/metric values more complex, but it
might make both sides happy.
second would be to allow negative numbers and flip "high is good" (or
"low is good" one) to the negative side.

Henning