NFD

Question is why different routing protocols' costs should be comparable. We won't have multiple intradomain routing protocols running at the same time on the same node. Interdomain and intradomain costs are not supposed to be comparable.

Routes can come from several sources:

• static route (manually configured by nfdc register)
• intra-domain routing protocol
• inter-domain routing protocol
• local application
• remote prefix registration (laptop registers a prefix on the access router toward the laptop)

The costs from all those sources are not comparable, but forwarding is using an order derived from those costs.

At 20141031 conference call @Lan says:

• Costs from different routing protocols are never comparable.
• IP's solution is administrative distance: a policy configured by operator.
• Some discussions are on http://www.lists.cs.ucla.edu/pipermail/nfd-dev/2014-October/000521.html thread.

@Beichuan suggests:

Define a range for local applications, and a range for external sources.
The range for local applications is smaller, so that they are preferred.

@Lan thinks this is similar to administrative distance. We are defining the preference of local applications statically.

@Lixia Zhang thinks the main question is to understand what Cost does other parties assign, as a reference of what Cost my application / routing protocol should assign.

Conclusion: we need to gain more experience in network operations before we can solve this problem.