Sending an Interest for each Data packet can lead to inefficiencies with respect to overhead and response time. Therefore, the concept of Persistent Interests (PIs) or Long Term Interests was introduced. The idea behind PIs is that multiple data packets are requested with a single Interest. This reduces the network overhead and relieves the network core, because fewer Interests must be processed. A classical Interest is sent over the network and stored in the Pending Interest Tables (PIT) of all forwarding nodes. If a matching Data packet is received, the corresponding PIT entry is marked as satisfied and deleted from the PIT. PIs behave similarly, the only difference is that a PIT entry of a PI is not marked as satisfied if a matching Data packet passes the node, but it stays in the PIT until its predefined lifetime times out.
Our first research in the field of Persistent Interests investigated the influence of PIs on estimated user satisfaction in terms of Internet telephony and discussed the difficulties in respect to making forwarding decisions. We published our findings on the MuSIC Workshop 2017 (see P. Moll, D. Posch and H. Hellwagner, “Investigation of push-based traffic for conversational services in Named Data Networking,” 2017 IEEE International Conference on Multimedia & Expo Workshops (ICMEW), Hong Kong, Hong Kong, 2017, pp. 315-320. [DOI, PDF]).
We developed and proposed a first forwarding strategy for Persistent Interests, which bases forwarding decisions on a combination of information from the FIB and probing results. In addition to PIs, clients issue probing Interests in order to rate paths through the network. All probe-receiving routers can use them to evaluate the performance of already known paths, but also to explore new, possibly better paths. This enables our strategy to react to network changes.
More information on our Adaptive Forwarding Strategy can be found in our Paper (see: P. Moll, J. Janda, and H. Hellwagner. 2017. Adaptive Forwarding of Persistent Interests in Named Data Networking. To appear in Proceedings of ACM Conference on Information-Centric Networking, Berlin, Germany, Sept. 2017 (ICN 2017), [PDF]) or on our Poster.