NFD

Scenario

• A gateway router is running nfd-autoreg which registers the same prefix for all connected laptops, using the same Route Cost.
• Multiple laptops are connected to the router.
• Each laptop serves a distinct prefix, which is a child prefix of the prefix registered by nfd-autoreg.
• The connection between laptop and router is lossy. Interest retransmission is needed to recover from packet loss.
• Traffic is realtime: delay is tolerable up to 500ms.

Expected: There exists a strategy that can allow contents retrieval in this scenario.

Actual: None of the existing strategies (best-route, ncc, broadcast) can support this scenario.

ncc and broadcast strategies are able to reach the correct laptop that can serve the Interest.
However, when there is a packet loss, these strategies don't permit Interest retransmission before InterestLifetime is over, so that packet loss is unrecoverable.

best-route strategy allows Interest retransmission once every 100ms, and retranmitted Interest goes to different nexthops in a round-robin fashion, where the nexthops are used in a fixed order.
It can recover from packet loss, and can reach the correct laptop after several retransmissions.

However, the realtime traffic can only tolerate 500ms delay, which allows at most 5 retranmissions.
Since Interest retransmission is triggered by consumer, consumer must have precise timing that lines up with the retransmission timer of best-route strategy in order to have 5 retransmissions, which is nearly impossible.

Even with 5 retransmission, when there are three laptops connected, the Interest will go in the order (laptopA, laptopB, laptopC, laptopA, laptopB).
If the correct laptop happens to be laptopC, a packet loss is unrecoverable.